EC-003 Amateur Radio Emergency Communications Level III

Learning Unit 1:

1. Consider the question: Is there such a thing as a universal leader, that is, one who leads effectively in every situation? What implications do you find in this question for emcomm groups? Summarize your findings and present them to your mentor.

2. In addition to the "trait" theory of leadership, there is a school of thought that suggests that leadership is a function undertaken by any member of a group. In this view, leadership is defined as any action taken by a group member who moves the group in the direction of its goal. For example, the production worker who develops a new, more productive procedure is as much a leader as the foreman who sets the production goal. Or the secretary who comes to work early to ensure that a report gets prepared on time is very much a task leader. Under this formulation, what are the opportunities for leadership in a small emcomm group? Share your thoughts with your mentor.

3. Select a leadership trait important to an emcomm group. Describe how you would design a training program to develop that trait in group members. Summarize your design and present it to your mentor.

Learning Unit 2:

1. Before your emcomm group can offer services to agencies within your area, you must be clear on a number of things. For purposes of the following, assume that yours is a new emcomm group.

a. Make a list of at least ten things you must know about your group before you make an offer of services to an agency.

b. Make a list of at least ten things you must know about the agency before you make an offer of services.

Share your results with your mentor.

2. Outline a "sales presentation" which you might make to an agency in behalf of your emcomm group.

a. Detail the "promises" you would make to an agency.

b. Detail the promises you would avoid making to an agency.

Share your results with your mentor.

3a. List and describe at least three critical challenges faced by emcomm groups that have arisen since 9-11.

3b.Describe the actions your emcomm group must take to meet each of these challenges.

Share your results with your mentor.

Learning Unit 3:

The following represents an initial, on-site "sales presentation" made by an emcomm group leader to the director of a small town's emergency services. After you have read the presentation, complete the three activities that have been outlined.

Group leader: "Hello Chief Smith. I am happy to meet you. I am John Roberts (KD7ZZZZ). I represent the Small Town Amateur Radio Club. My brother-in-law, the Mayor told me to speak to you about providing emergency Amateur Radio services.

"Here is what we propose:

a. First, we have some very experienced hams who (with only a slight bit of training) can take over your 911 system and your emergency dispatch center during disasters.

b. We are also willing to take over the routine maintenance of all the town's radio equipment.

c. And since we have two members who have completed the basic first aid course, we believe that we can provide extra help by riding along in the town's ambulances.

"As I said before, our people are quite knowledgeable about your operations because three of them visited the fire station during the open house last year and two of them actually accompanied your deputies on the "citizen ride along" program you had yesterday.

"I have brought along a Memorandum of Understanding for you to sign; but before we get into that, I have a couple of questions for you:

"First, when will it be possible for you to deputize the members of our group? Second, will they be paid at the level of beginning firemen or at the administrative level? Finally, where will my office be located?"

1. Identify at least eight errors made during this presentation.
2. For each error, specify WHAT is wrong, and WHY.
3. Prepare a sales presentation for your own group AVOIDING the errors you have identified above.

Share your results with your mentor.

Learning Unit 4:

Assume that you represent an ARES group and have been asked to make a presentation to an Emergency Management Agency in your area. In anticipation of the topic of RACES being raised, you are to prepare a special display.

The display consists of a chart with two columns and seven rows that compares and contrasts ARES and RACES. The labels at the top of the two columns are "ARES" and "RACES." The rows must consist of at least seven points of comparison and contrast between the two radio groups.

Include these four points, and add at least three more of your own.

• History
• Applicable FCC Rules
• Eligibility for membership
• How ARES and EMA volunteers are organized in your Section

Share your results with your Mentor.

Learning Unit 5:

1. Answer the following questions:

a. In what ways is an MOU similar to a written contract?

b. In what ways do MOUs and contracts differ?

Share your results with your mentor.

2. Suppose you were assigned to develop a Memorandum of Understanding between your emcomm group and a local agency.

a. List the things you would need to know before you coulddevelop such a document.

b. List some of the items you would include in the MOU.

c. List some of the items you would exclude from the MOU.

Share your results with your mentor.

Learning Unit 6:

1. Define the following terms and provide an example of each:

a. VOAD

b. NVOAD

Share your results with your mentor.

2. List the items of information you would need to have on hand before your local organization joined a VOAD. Share your results with your Mentor

Learning Unit 7:

Prepare a summary chart or outline in which you define and identify the functions of each of the following elements:

(a) INRP

(b) Final NRP

(c) NIMS

(d) ICS

(e) NIMS-NIC

(f) JIS

(g) JIC

(h) Served agencies

(i) Amateur Radio operators.

After you have defined each of the elements, identify how they are related.

Share your work with your mentor.

Learning Unit 8:

1. Consider the current Federal plan for responding to emergencies. Detail at least three implications the current plan has for Amateur Radio and for emcomm groups.

Share your results with your Mentor.

2. Prepare a glossary of six key words and acronyms used in this Learning Unit.

Share your results with your Mentor.

3. Within your emcomm group, you have been designated as the resident expert on Federal emergency planning. You have been asked to provide an overview of the current status of Federal emergency planning to your group. Prepare an outlineof your presentation.

Share your results with your Mentor.

Learning Unit 9:

1. As written, the Emergency Support Functions have a number of implications for Amateur Radio and specifically for emcomm groups. List at least five such implications. Share your results with your Mentor.

2. Compile a list of informational resources regarding ESFs. Your list should include Federal, State and Local resources. Share your results with your mentor.

3. Your state's emergency manager has just announced that planning for ESF participation is a priority for all local emcomm groups. In turn, the leader of your emcomm group has designated you as the group's ESF expert. Your initial assignment is to develop a list of the ten most important things your group needs to know about the ESFs in your state's plan. Share your results with your mentor.

Learning Unit 10:

1. List at least six ways in which Amateur Radio Operators and CERT teams benefit from working together in an emergency. Share your results with your Mentor.

2. Develop a description of the CERT organization within your city, county or state. If no such organization currently exists, describe the initial steps that would have to be taken to create such an organization. Share your results with your Mentor.

3. Suppose that you were assigned to train a new CERT team in the area of emergency communications. Develop a list of at least ten items that you would include in your first instructional presentation to them. Share your results with your Mentor.

Learning Unit 11:

1. You have been asked to brief the leaders of emcomm teams in your area on the topic of communication support for the National Disaster Medical System. Prepare an outline of your presentation. Share your results with your Mentor.

2. List the steps you would have to take to determine the status of DMAT organization(s) in your area. Share your results with your Mentor.

Learning Unit 12:

1. Your emcomm group is considering a new mission -- the support of a local hospital. Specifically, if your group goes forward with this decision, it would become primarily a Hospital Disaster Support Communication System.

a. What would your group need to know in order to make a good decision in this matter?

b. What factors do you believe would weigh the most in your group's decision?

Share your work with your mentor.

2. Suppose your emcomm group consists of 20 individuals. Further suppose that your group has made the decision to become a disaster communications support group to a small hospital.

a. Develop a staffing plan suitable for your new mission.

b. Develop an equipment plan suitable for your new mission.

c. Develop a training plan suitable for your new mission.

Share your work with your mentor.

Learning Unit 13:

1. Acquiring and retaining an active, viable membership is a challenge for any volunteer group. It is especially challenging for an emcomm group whose membership requirements allow only a tiny fraction of the population to join.

a. List five approaches to recruitment of new members for your emcomm group.

b. List five approaches to retaining active members of your emcomm group.

Share your results with your mentor.

2a. Compile a list of at least five errors to avoid in recruiting new members.

b. Complete a list of at least five errors to avoid in retaining active members.

Share your results with your mentor.

3. You are stepping down from your position as EC. What three pieces of advice regarding membership do you have for the person who is succeeding you?

Share your results with your mentor.

Learning Unit 14:

1) Spontaneous volunteers may be assigned to a variety of tasks. Identify at least five such tasks that may be assigned to spontaneous volunteers.

Share your results with your Mentor.

2) Assigning spontaneous volunteers to specific tasks is one thing; having them carry out the tasks successfully is a separate issue. One way of assisting the volunteers to conduct the task appropriately is to provide them with a written description of the task. Having such a description at hand not only guides the volunteer in the performance of assigned duties, but it can also reduce the amount of supervisory effort required.

From the tasks you have identified above, select at least one. Using the guide below, develop a description for each task you have selected.

Task Guide

A typical task description might contain the following information:

1 - Task title

2 - Location - where the task is to be performed.

3 - Immediate supervisor-(name, title and means of contacting).

4 - Supplies or equipment required (and location of same).

5 - Objective of the task.

6 - Criteria for successfully completing the task.

7 - Method/methods to be employed.

8 - Errors to avoid in conducting the task.

9 - Documentation requirements -- if any.

10 - Limits on assigned authority (i.e., decisions which can be made by the volunteer and decisions which must be referred to the supervisor)

11 - Duration of task and relief arrangements.

12 - Additionally on the master copy of the guide (not the copy provided to volunteers), note the skills and knowledge requirements for the task.

Share your results with your mentor.

3) Assigning spontaneous volunteers to specific tasks represents a considerable challenge. If the task is too easy for the volunteer, boredom (and hence resentment) may result; if the task is beyond the capability of the volunteer, it will not be well done.

The solution here is to match task difficulty with volunteer capability. One means of accomplishing such a match is to employ an enrollment form which yields information about the capabilities of the spontaneous volunteer.

Your assignment here is to develop a Volunteer Enrollment Form which will help you match spontaneous volunteers with task assignments. In developing the Volunteer Enrollment Form, refer to item 12 in the Task Guide above.

Share your results with your Mentor.

Learning Unit 15:

Create a time-line for a simulated actual disaster of your choice, beginning with the warning phase, and ending with stand-down. Write it as though you are recording the events of an actual recent disaster, using details discussed in this unit. Describe specific actions that your group would take in each phase. Share it with your mentor.

Optional Activities (Highly recommended, but not required): You may discuss these optional activities with your mentor if you wish.

1. Create a list of the possible disasters that could occur in your area, and assign each a level of probability. Use whatever information is available to develop the list, or base your list on history and your own judgment.

2. For each disaster that has a high probability of occurring in your area, list the possible impacts of this disaster on the community and the sort of response emergency services will have to make.

3. For the disasters listed in Optional Activity 2, consider any possible communication system failures, and how your local ARES/RACES teams might assist. What sort of planning and preparation will be needed for each failure mode listed?

4. Outline a basic communications response plan for a high probability disaster.

Learning Unit 16:

1. Compare the various ARCT types along the following dimensions:

• Personnel
• Personnel qualifications
• Mode of operation
• Equipment

(Suggestion: A display table with ARCT types across the top and the descriptive dimensions along the edge will simplify the task.) Share your results with your mentor.

2a. You are the leader of a local Emcomm group. A wide-spread emergency has arisen in your area. The lead emergency management agency in your area has contacted you and placed the following ARCT order:

• Two Type I
• Two Type 3
• Three Type 5.

Describe the staff (including qualifications), modes of operation, and the equipment you would need to fill this order. Share your results with your mentor.

2b. The lead emergency management agency has reconsidered its earlier request. The revised order is as follows:

• Three Type I
• Two Type 2
• One Type 3
• Three Type 5

Describe the staff (including qualifications), the modes of operation and the equipment you would need to fill this order. Share your results with your mentor.

Learning Unit 17:

1a. Develop a three level mobilization plan for a small town ARES team. The town is located in a mountainous region with numerous deep valleys. Team members (of which there are 20) live within 25 miles of the town. The assembly point is at the town hall.

1b. Adapt your three level mobilization plan (see 1a) to accommodate an ARES team in your locale.

Share your results with your mentor.

2a. Develop a net plan for the small town described above. The served agency in this case is the town emergency services department. Ordinarily the served agency operates from the town hall with additional operations at two fire stations and a relief center at the local high school. The office of the county's emergency coordinator is located 50 miles away.

2b. Adapt your net plan (see 2a) to accommodate an ARES team in your locale.

Share your results with your mentor.

3a. List the errors you would seek to avoid in conducting a post-emergency debriefing.

3b. Develop a list of topics or questions you would use to guide the post-emergency debriefing.

Share your results with your mentor.

Learning Unit 18:

1a. The communication plan for the Small Town Emcomm Team contains the following phrase: "Operate a tactical phone net which encompasses three remote stations and one central station."

Your task here is to identify the skills that would be required to support this portion of the communication plan. List at least five skills in addition to the following examples.

Examples: (1) Operators must be able to set up the equipment.

(2) Operators must be able to tune the equipment to the correct frequencies.

1b. Suggest a method for training team members on each skill you have identified.

Share your results with your mentor.

2a. Consider the skill set of a Net Controller. List three of the skills you believe are important for this position.

2b. For each of the skills you have listed, briefly describe a training exercise that would teach those skills.

Share your results with your mentor.

3a. Consider your own experiences with training exercises. What was your best experience? Describe what made it effective.

3b. What was your worst training experience? Describe what made it ineffective.

3c. Based on the foregoing, develop a short list of rules for conducting training exercises.

Share your results with your mentor.

Learning Unit 19:

Talk with the leader of a local ARESMAT if one exists, and discuss any recent deployments. If no ARESMAT exists in your local area, contact your ARES leadership (usually an Emergency Coordinator), and learn what other plans, if any, have been made to provide mutual aid assistance to neighboring ARES groups. Share the results of your meetings with your Mentor.

Learning Unit 20:

1. Develop an organizational chart which depicts all of the major positions beginning with the ARRL Headquarters staff and extending to your local Emcomm group. Label each position. Share your results with your Mentor.

2. In outline form, write a brief job description for a DEC. Share your results with your Mentor

[Note to the student: Do either Activity 3 for Sections without Districts, or Activity 4 for those with Districts.]

3a. If your Section does NOT contain Districts, develop a list of factors that should be considered if your Section were to be sub-divided into Districts.

b. Use that list to make a recommendation for either dividing or not dividing your Section into Districts. Provide a rationale for your recommendation. Share your results with your Mentor

4a. If your Section is divided into Districts, develop a list of factors that should be considered if the current Districts were to be consolidated.

b. Use that list to make a recommendation for either consolidating or not consolidating Districts in your Section. Provide a rationale for your recommendation. Share your results with your Mentor

Learning Unit 21:

1. You are in charge of providing training to new members of your Emcomm group. Given the importance of FCC emergency communication rules, you plan to prepare a wallet card of the rules for the new members.

In as few words as possible, outline the FCC rules which govern emergency communications for Amateurs. Share your results with your Mentor.

2. In providing training to new members of your Emcomm group, you wish to stress errors to be avoided during emergency communications. Outline at least six such errors. Share your results with your Mentor.

3. Prepare a check-list for obtaining an ECD in your area. On the check-list,

You are to include in outline form:

(a) the information you would need,

(b) the contacts you would make and

(c) the steps you would take to obtain the ECD.

Share your results with your Mentor.

Learning Unit 22:

1. Compare the advantages and disadvantages of various types of vehicles for use as mobile communication vehicles in your own area. Share your results with your mentor.

2a. Develop in outline form a prioritized list of equipment you would install in a mobile communication vehicle for your area. Begin your list with the most important item(s). Share your results with your mentor.

2b. Develop a cost estimate for the prioritized list of equipment you generated above. If your estimate includes donations, provide a cost equivalent figure. Your final estimate should contain two figures:

(a) the sum total "out of pocket" expenditures and

(b) the total value of the equipment -- including the donations.

Share your results with your mentor

Learning Unit 23:

1. Develop a brief document which addresses the similarities and differences among the following organizations with regard to how they provide emergency communications:

• ARRL
• State and local emergency management agencies
• REACT.

Share your results with your Mentor.

2a. Describe the steps you would take to determine if there is a REACT organization in your local community.

2b. Follow the steps you have outlined above. What did you find?

Share your results with your Mentor.

EC-006 Radio Frequency Interference

LU 1

Disconnect your transmission line from your HF receiver, connect 10 -- 20 feet of hookup wire to the antenna input, and tune through the 80 meter band, 3.5-4.0 MHz. Record the frequencies of noise sources you hear. Turn off your computer monitors and try again. Try again with your computers totally off, then all TVs in your house off. (You may want to wait until your family is out of the house!) Are there still other sources of noise? See if you can locate all sources in your house and on your property. As an option, you can try this again with your HF antenna properly connected to see the difference good transmission line and an outside antenna make. Report what you find to your mentor.

LU 2

You will need: A portable radio, AM or FM or both; a roll of aluminum foil.

Check out the effects of total shielding. Turn on the radio and pick up a strong station in your area. Now wrap the foil around the radio leaving no openings. See how much you have to open the foil before you hear something. Touch the antenna and try it again. Report your findings to your mentor.

LU 3

Use your AM radio plugged into a wall outlet as a test device. Wrap the antenna of your noise generator (See Figure 3.12) around the cord of the radio two times, loosely. Now attach a clamp-on ferrite bead filter to the cord between the noise generator antenna and the radio. Did it help? If you can, obtain a commercial AC-line filter and insert it in the cord of your radio. Now experiment with placing the antenna on the radio side and the plug side of the filter. See what works best. Report your results to your mentor.

LU 4

Turn off the AGC in your HF receiver and tune the 80 meter band to see if you hear harmonics of local broadcast stations. Review the list of stations in your area and find a pair whose difference frequency doubled is in the 160 meter band or tripled is in the 80 meter band. See if you can find those signals. Report your findings to your mentor.

LU 5

Connect a TV to the same duplex outlet or power strip that powers your transmitter. Check for TVI while transmitting on all bands that you normally use. Report your findings to your mentor.

LU 6

An AM radio is one of the most sensitive detectors of radio noise. Carry your portable AM radio around your house, near your home thermostat, lamp dimmers, blender, vacuum cleaner, etc. Try checking out the difference with battery operation of the radio listening for radiated RF and "plugged in" operation listening for conducted RF. Use your car's AM radio, or take your portable for a long walk, and see if you can find some local noise sources. Report your findings to your mentor.

LU 7

Explore the environment around your own car with the engine running using your HT and your portable AM radio with the hood closed then with the hood open. Be careful when the hood is open! Do not put your hands inside the engine compartment when the motor is running. Do not allow the HT or antenna to get closer than 6 inches to any high voltage wiring. Report what you find to your mentor.

LU 8

Check out TV sets in your own house while operating your station. Check antenna connected channels 2, 3 and 4 while operating in the 20, 15, and 10 meter bands and cable channel 18 while operating your two-meter HT next to the TV set. Consider yourself lucky if you have no commercial stations on those channels! Report your findings to your mentor.

LU 9

Connect a stereo or audio amplifier to the same outlet or plug strip that powers your HF transceiver. Transmit on the bands you normally use and see if you interfere through the power line. Disconnect the audio input device (CDROM, tuner, tape player, etc.), leave the input open and see if your ham rig interferes. Repeat for the input shorted and with a 400-600 ohm resistor on the input. Report your results to your mentor.

LU 10

Investigate the telephone RFI situation in your own house while you or another ham operate your equipment. You may have already heard the howls from other members of your family! Report your results to your mentor.

LU 11

Download your own copy of the FCC Interference Handbook (See the RFI Book, page 17.6:, look it over and briefly provide your mentor with your thoughts about how helpful this handbook could be to you.

LU 12

This is optional. Visit your neighbors and ask if they have any interference problems. You may be surprised and they may be surprised at your help and cooperation. Report what you find to your mentor.

LU 13

Optional: Contact your local ARRL Technical Coordinator (You may have to contact your Section Manager. See QST to get a name and phone number), to find your local RFI specialist. Go with him/her on a trouble call and observe the techniques they use.

EC-009 Antenna Design & Construction

LU 2 --

Mentor Discussion

1. Calculate the length of the antenna's radiating element if it was to be used at 224 MHz and at 446 MHz.

2. How do you think the ground-plane circuit is completed for an antenna that mounts on a metal surface with a magnet (a mag mount)?

3. Identify two or three types of non-amateur ground-plane antennas you have seen.

Construction Project (Optional)

If you undertake the construction project, report to your mentor:

a. What construction problems did you have? Did you improvise with other construction methods or materials?

b. Were you able to observe the predicted effects from aiming the antenna in different directions?

c. How might you mount this antenna permanently?

1. Construct the 2-meter quarter-wave ground-plane antenna as described in the reference text and connect the coaxial cable to the SO-239.

2. Hold the molding or dowel against the cable with one end against the flange of the SO-239. Use the electrical tape to attach the dowel to the cable as shown in the following figure. The dowel will be used as a handle for the assembled antenna.

3. Connect the cable to your radio and tune in an active repeater or have a friend transmit on low power from several hundred feet away while holding his antenna vertical. Hold the antenna above your head, oriented vertically. Note the received signal strength. If the signal strength is at the maximum displayed level, either find a weaker repeater signal or have your friend reduce power so that the indicator shows about 80 -- 90% of maximum signal strength.

4. While the repeater or your friend is transmitting, watch the indicator while you slowly lower the antenna directly towards the transmitted signal source. By carefully pointing the antenna directly at the source, you should be able to see a "dip" or "null" close to directly off the end of the antenna.

5. As the repeater or friend continues to transmit, slowly pivot, swinging the antenna in an arc until it is perpendicular to the direction to the transmitter. Note the signal strength as you swing the antenna. It should increase again, but will probably not reach the same strength as in step 3 because your antenna is now horizontally-polarized while the transmitted signal is polarized vertically. The two antennas are "cross-polarized" and the difference in signals is called "polarization loss".

6. Continue to pivot until your antenna is pointed directly away from the transmitted signal source. In this direction, the received signal will be even weaker than in step 4 due to the shielding effect of the antenna's ground-plane and your body.

7. Continue to pivot while watching the received signal strength until you are again pointing directly at the signal source. Return the antenna to point directly overhead. This exercise should allow you to visualize the antenna's radiation pattern described earlier in this lesson.

LU 3 --

Mentor Discussion

1. Using the formula for the length of a half-wave dipole in the lesson, calculate the length of a dipole at 3.9, 14.2, and 24.9 MHz.

2. Using a length of rope or heavy cord, dangle it vertically and shake the end back and forth so that a stable pattern of high movement at each end and little movement in the middle develops. If this was a dipole antenna, the current (back-and-forth movement) would be high on each end and zero in the middle. Where would you find a high-current, low-voltage point on such an antenna to attach a coax feed line?

3. Tie one end to a fixed point and experiment with shaking it at different frequencies where stable patterns of vibration occur.

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. What construction problems did you have? Did you improvise with other construction methods or materials?

b. Did the antenna perform electrically as you expected? If not, what did you observe that was unexpected?

c. Were the lengths of wire about what you calculated for the various bands?

The activity for this lesson is to construct the "Roll-Up Dipole" from Chapter 7 of the reference text. More accurately named the "Roll-Up Inverted-V", you will find this to be a very useful portable antenna for camping, Field Day, and emergency communications--just the thing to have packed up and ready to go. You can make the antenna of nearly any size, but a good starting project is one that will cover 40 through 6-meters.

Refer to Table 1 in the Introductory Lesson for all the materials needed for this assembly project. Two items may be homemade, if desired. The first is the center insulator for the V. In order to keep the antenna as portable as possible, it is desirable to have a coax connector on the center insulator so that the feed line can be disconnected. Several commercial models are available and one with a hole for a supporting rope is best. If you decide to "roll your own", Figure 4 will give you some ideas. Almost any variation on this theme will do--do not be afraid to experiment!

The second homemade item is the guy-rope sliders as shown in Figure 5. These will allow you to attach the guying ropes anywhere along the antenna without using a knot as you lengthen and shorten the antenna's arms. You can also use tent guying sliders, if they are non-conductive. It will also help keep things shipshape, once installed, if you put a hook on the wire spool so that you can hang the spool on the guy rope with the surplus wire coiled up.

Follow the instructions in the reference text and use the length guidelines for the bands you choose. Assuming you are building for 40-meters as the lowest band, you will need 35' of wire on each spool. Unroll a foot more than the 32' called for in the table. Transmitting the minimum output power, use your SWR meter to find the frequency of minimum SWR on the 40-meter band. If the antenna is too long the minimum SWR point may be below the band. If it is, wind 6" of wire back onto each spool and check the SWR again. Keep going until you have the minimum SWR where you want it on the band. At this point, use weatherproof tape or marker to label the antenna wire.

Repeat this process for each amateur band above 7 MHz. You might want to mark the length that works at the third harmonic on 21 MHz. Do not be too concerned with getting the minimum SWR as low as possible. Nearly all transmitters will be happy with any SWR under 2:1 and often higher than that.

LU 4 --

Mentor Discussion:

Survey your home or the neighborhood and survey different locations in which you would install a ground-mounted vertical, an inverted-V using a single support, and a roof-mounted VHF ground-plane.

Report to your mentor:

a. the type and height of support

b. how you would mount the antenna

c. any safety issues for the antenna installer to consider during installation

d. and safety issues for the public regarding the antenna, once installed

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. What problems did you have? Did you improvise with other methods or materials?

b. Did the antenna perform electrically as you expected when installed? If not, what did you observe that was unexpected?

Your assignment is to install either of the antennas that you built for Lessons 2 and 3. If you decide to put up the vertical, you might try making a portable stand for it or even installing it on the outside of your house or apartment. The Roll-Up Inverted Vee would be a great opportunity to test your hand in the eternal struggle between hams and trees. Good luck!

LU 5 --

Mentor Discussion:

1. Fill a round pan or bowl halfway with water. Place your index finger vertically in the water at the center of the pan and vibrate it up and down rapidly enough to make a steady pattern of ripples in the pan. Observe the pattern of ripples. Now move your finger to another location about halfway to one edge of the container and repeat. Report on the pattern of reflected ripples and any points where the ripples seem to add or cancel.

2. Now use both your index fingers a few "ripple-lengths" apart and make a pattern of ripples. Can you see the ripples adding and subtracting? (Another way to create two sets of ripples is to use a pair of pencils taped to a ruler.) Try to make your fingers move in-phase (up and down at the same time) and out-of-phase. How does this relate to the radiated field from two antenna currents?

3. Considering the bi-Square antenna, if the antenna does not radiate to either side and has peak radiation broadside to the antenna, what happens straight above and below the antenna?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. What problems did you have? Did you improvise with other methods or materials?

b. Report on how the antenna was finally installed.

c. Make a few contacts, if you are licensed to do so, and report on the received and reported signal strengths in different directions.

Build and test the 12-meter EDZ described in the reference text. If you have appropriately positioned supports, change the orientation of the antenna to favor signals at right angles to the initial position. See if you can hear a difference in which directions the signals are received best.

LU 6 --

Mentor Discussion:

1. What bad effects would exposure to weather have on a transmission line? How might you attempt to prevent those effects?

2. Look through a ham radio vendor catalog or Web site and report on the different types of coaxial and open-wire line for sale, including their characteristic impedances.

3. If you had a spool of copper wire, what materials in your kitchen or workshop could you use to make open-wire feed line?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. The table of SWR measurements you made, including the forward and reflected power readings.

b. Did the measurements agree with your expectations? Was the frequency of minimum SWR where you expected it?

c. Did you have any problems measuring forward and reflected power?

Set up the Roll-up inverted-V from Lesson 3 on any convenient band. Use your SWR/Power Meter to measure the forward and reflected power at 10 frequencies evenly spaced across the band. Determine the SWR using the formula from the lesson. Determine the frequency of minimum SWR. Figure 3 shows a typical curve for a 20-meter inverted-V with its apex 40' above the ground generated by the EZNEC modelling software.

Obtain some RG-58 or RG-213 and make a couple of 3' -- 6' jumpers with PL-259's on each end--very useful around the shack. Be sure to solder the braid to the shell as described in the reference text. Yank on them to be sure you have done a good job mechanically. Use your voltmeter to check resistance (both end-to-end and from center conductor to shield) while wiggling and twisting the connector. If you see a short or open circuit, even temporarily, replace the connector!

EZNEC is a registered trademark of Roy Lewellan, W7EL. (http://www.eznec.com)

LU 7 --

Mentor Discussion:

1. Discuss why current flowing on the outside of a coaxial feed line shield would be undesirable?

2. Would open-wire line be susceptible to the same problem?

3. If you were to extend the J-pole's radiating element to lengths beyond 1/2-wavelength, what would happen to the radiation pattern? Would this result in stronger or weaker signal strength at a distant repeater?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. What problems did you have? Did you improvise with other methods or materials?

b. Did the antenna perform electrically as you expected when installed? If not, what did you observe that was unexpected?

Build the 2-meter twinlead J-pole described in the reference text. It is not necessary to build the full tubular enclosure unless you plan to make the antenna's installation permanent. Measure the antenna's SWR across the 2-meter band.

While running a low power (<5W) to the antenna, watch the SWR while you touch various points on the feed line and antenna with a screwdriver or other conductive object. Bring the screwdriver close to the quarter-wave stub in parallel and at right angles to it to observe the effect of nearby conductive objects on the open-wire line.

LU 8 --

Mentor Discussion:

1. Identify several locations where you might install a 40-meter ground-mounted quarter-wave vertical antenna. Discuss the strong and weak points of each location from a mechanical and radio viewpoint.

2. What materials in a household hardware store - other than wire - could you use to make a ground screen?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. What problems did you have? Did you improvise with other methods or materials?

b. Did the antenna perform electrically as you expected when installed? If not, what did you observe that was unexpected?

This lesson's activity can be either of two choices. You may build the 10-Meter Ground Plane antenna described in the reference text article or you can adapt a Citizen's Band (CB) 1/4-l whip antenna, which is slightly longer than for the amateur 10-meter band.

If you choose the second option, obtain a steel or fiberglass CB whip antenna. It should be a little over 8' long and have a 3/8"-24 threaded mount. Purchase a RadioShack model 21-961 coaxial adapter so that you can connect your feed line to the antenna. A several inch length of 1-1/2" aluminum angle and small U-bolt will allow you to mount the antenna on a pole or mast.

Prepare the aluminum angle as shown in Figure 4 and mount the unmodified antenna. Attach two 8' radial wires to the aluminum angle. Now use a hacksaw and remove about 3% of the whip's length (which includes the threaded mount.) The amateur 10-meter band (assuming a frequency of 28.4 MHz) is about 4% higher in frequency than CB. We'll remove a little less than needed and trim to frequency in short steps.

Mount the antenna in the clear, 5' or 6' above the ground and with the radial wires held straight out on opposite sides. Check SWR using your transmitter (on very low power) or SWR meter. It should reach a minimum value at a frequency near the bottom of the 10-meter band. Remove 1/2" from the whip at a time until a minimum SWR is found near 28.3 MHz. The whip will be useful over a wide bandwidth, so you do not have to be exact. For fiberglass whips, use a small plastic cap to cover the cut end. On steel whips, a split-shot lead sinker can be crimped around the sharp end.

Now, for either antenna, temporarily mount the radiating element on a wooden stick or post a 2 - 3" above the ground. Attach just two radials and stretch them out along the ground. Measure and plot SWR every 200 kHz from 28.0 to 29.0 MHz. Repeat the measurements with four, eight, and sixteen radials. If you have a friend that can assist you, have him or her report on your signal strength as you add radials. Compare the changes in SWR and signal strength. You will probably see the SWR curve become less flat as radials are added. This is a sign of lower losses in the antenna system.

LU 9 --

Mentor Discussion:

1. Calculate the SWR for the following combinations of characteristic and load impedances:

a. Line - 50 ohms and Load - 110 ohms

b. Line - 300 ohms and Load - 75 ohms

c. Line - 75 ohms and Load - 300 ohms

2. Calculate the desired characteristic impedance for a quarter-wave transformer for each of the combinations of characteristic and load impedances above.

3. Where in your station would you be able to place a quarter-wave stub? Under what circumstances would you need to use a stub as a filter?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. What problems did you have? Did you improvise with other methods or materials?

b. Could you hear the difference in the receiver when you changed the switch setting? If not, what did you observe?

For this lesson's activity, we will make a very useful switchable stub that acts as a band-selectable filter on four of the HF bands. The stub is cut as a quarter-wavelength on 40-meters and fitted with a toggle switch that can either short or open the end of the stub. If the switch is closed, shorting the stub, at its input it will act as an open-circuit on 40- and 15-meters and a short-circuit on 20- and 10-meters, reducing interference to and from those bands. If the switch is open, the stub will act like a short on 40- and 15-meters and an open-circuit on 20- and 10-meters. (This corresponds to the second set of bands in the table shown in Figure 3.)

The stub's design frequency will be 7.075 MHz with harmonics of 14.150, 21.225, and 28.300 MHz--all close to mid-band. That set of frequencies will give good performance on both phone and CW.

A free-space quarter-wave at 7.075 MHz is 34.78'. Including the velocity factor of 66%, the stub should be close to 23' long. We'll start a little long and trim to length. Start by installing a PL-259 connector on a 25' length of 50-ohm coaxial cable with a solid polyethylene insulator, such as RG-58C or RG-213. Cut the stub to 24' 3" long, including the PL-259 connector, which must be included in the stub length.

Next, make a temporary short at the remaining end of the cable by stripping 1/4" of center conductor and twisting it together with the shield braid. Use the tee-connector at the output of your rig to connect the stub in parallel with a 20-meter antenna. Be sure to disable the key or mike switch so that you cannot transmit. Listen to the band noise as you tune the receiver and listen for the frequency at which noise drops to a minimum. If it drops to a minimum over a range of frequencies, estimate the center frequency of the range.

Trim 1/2" from the stub at a time, restoring the short with each trim and recheck the minimum noise frequency until you are close to 14.150 MHz. When that point is reached, temporarily solder the toggle switch to the ends of the stub, adding no additional lead length. Recheck the stub's design frequency with the toggle switch. If it has moved below 14.100 MHz, remove the toggle switch, trim a small amount of cable, and reattach the toggle switch. Repeat the noise check until the noise minimum is within 25 kHz of 14.150 MHz.

Remove the toggle switch and install it on the cap of the film can. Drill a hole in the bottom of the can and slide it over the stub, bottom first. Securely solder the toggle switch to the stub, taking care that no stray wires can cause an unwanted short. Slide the can bottom back up the cable and close.

You now have a handy filter for Field Day or emergency use when other transmitters may be nearby. Be sure to set the switch to the correct position on each band. The noise level should tip you off if it is set to the wrong band for transmitting.

LU 10 --

Mentor Discussion:

1. Describe any antennas that you own that have built-in impedance matching. If you do not own any such antennas, identify two or three from catalogs or Web sites and describe their impedance matching devices.

2. Where in your station's antenna system would you install a choke balun? Would you prefer a coiled-coax or ferrite bead model? Why?

3. If a transmitter is generating harmonics, would the T-network tuner in Figure 4 attenuate or pass them? Why?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. Were you able to achieve a low SWR with the antenna tuner?

b. Did changing frequency within the band require frequent retuning?

c. If you were not able to obtain low SWR, did changing frequency within the band make a difference?

d. Did you try the antenna on different bands?

Use your antenna tuner to match an antenna on a band for which it is not designed. For example, try using a 40-meter dipole on 12-meters. Keep the transmitter output power to a minimum while you experiment and do not forget to identify your transmissions.

If you would like to give this a try, but do not have a tuner or the requisite antenna farm, try W9CF's excellent T-network simulator at http://fermi.la.asu.edu/w9cf/tuner/tuner.html. Enter possible load impedance values (inductive load reactance is entered as a positive value in the "X Load" field) and frequencies and start cranking those knobs. Your transmitter will NEVER overheat! Try impedance values of 10, 20, 100, 300, and 1500 ohms in combination with X Load values of positive and negative 50, 100, and 500 ohms. Don't be afraid to experiment!

LU 11 --

Mentor Discussion:

1. Identify two or three different applications for small VHF phased-array antennas.

2. Along a line in what direction would you orient the array of 3a in order to null out a signal from the East? From the South?

3. Design a half-square antenna that you could use at or in your home for any amateur band below 144 MHz. In which direction is it mounted and in which directions will it radiate best?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. Could you hear the difference in the received signal as you rotated the array? If not, what did you observe?

b. For spacings greater than 1/2-wavelength, could you detect the multiple lobes? If not, what did you observe?

Build another 2-meter quarter-wavelength ground-plane identical to the one you built in Lesson 2. Also construct three coaxial cables with PL-259's on each end; two 5/4-l long and one l/2 long at 147 MHz. If you are using coax with a 66% velocity factor the line lengths including the PL-259 connector will be and 66" and 26-1/2", respectively.

Obtain a 1x2 furring strip from 6' to 12' long. Drill 3/4" holes spaced 20" on centers apart along the strip. This results in a strip with a series of holes l/4 apart as shown in Figure 7.

Push the two 5/4-l jumpers through a pair of the holes l/2 apart (40") and connect the ground-planes as shown in the figure. Connect the jumpers together with a tee-connector and then to your 2-meter radio. This is a 2-vertical broadside array.

Hold the furring strip over your head and aim the antenna's broadsidelobe at a distant signal source while watching your received signal strength indicator. Rotate the antenna 90° and you should find a null off either end of the array. Rotating the antenna another 90° should bring the signal back to full strength.

Now add the l/2 section of line using a double-female (or "barrel") adapter as shown in the figure, inverting the phase of one antenna. If the antennas are l/2 apart (2 holes), then the signal should peak off the ends of the array.

Experiment by moving the antennas to different spacings and using different combinations of line length. See if you can correlate the array's spacing and phase to the signal strengths you observe as you rotate the array.

LU 12 --

Mentor Discussion:

1. Identify several examples of Yagi antennas as you go about your daily affairs. Estimate how big they are and for what frequency they are intended.

2. If you needed to increase the signal strength from your dipole by an S-unit (6 dB), which of the antennas in figure 3 would suffice? By how many S-units would the Yagis of figure 3 attenuate a signal coming from the rear of the antenna?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. What problems did you have? Did you improvise with other methods or materials?

b. Did the antenna perform electrically as you expected when installed? If not, what did you observe that was unexpected?

In this activity, you will construct a simple, 3-element Yagi antenna from copper wire as shown in Figure 4.

Cut three pieces of #14 copper wire as shown in the figure and straighten them out. Cut the length for the DE exactly in half and bend as shown. Attach the DE halves to the furring strip with cable staples or tacks. Solder the center conductor and shield of a 6' to 10' piece of coaxial cable to the DE as shown in the figure and secure to the 1x2 with tape or cable ties.

Attach the reflector or director to the furring strip with cable staples or tacks. Attach the remaining end of the coaxial cable to your 2-meter radio. Tune in a medium-strength station and point the antenna directly at it, noting the maximum signal strength. Slowly move the antenna away from the signal source, noting at what bearings the signal reaches a minimum near the side and off the back of the antenna. Rotate the axis of the antenna, observing signal strength with the elements horizontal and vertical. Determine with what polarization (horizontal or vertical) the signal is transmitted.

Remove the parasitic element and replace it with the other one and repeat the experiment. Both two-element Yagis should have about the same performance.

Now attach both parasitic elements and note any differences in forward gain (maybe a little) and F/B (should be dramatically different.)

If you want, build on this activity by constructing the six-element 2-meter Yagi described in chapter 13 of the reference text. For temporary or portable use, the PVC pipe method is recommended. If the antenna is to be used outdoors, UV-resistant pipe such as outdoor-rated plastic conduit should be used.

LU 13 --

Mentor Discussion:

1. Can you scale the antenna and feed line of Figure 3 so that it will present a high-impedance at the end of the feed line on both 30- and 60-meters?

2. On what frequency does a 31.6' length of open-wire line with a 95% velocity factor act like an electrical half-wavelength?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. Did the antenna perform electrically as you expected when installed? If not, what did you observe that was unexpected?

b. Were the lengths as you expected for both sets of frequencies?

Configure the Roll-Up Inverted-V constructed in Lesson 3 for 40-meters. Measure the antenna's SWR on 40- and 15-meters. Adjust the antenna length for a satisfactory match on both bands. Repeat the exercise on 30- and 10-meters.

If you wish, construct the "Dual-Band Mobile Whip for 146/446 MHz" in Chapter 8 of the reference text. This antenna uses a stub in place of a trap to separate the antenna electrically into a quarter-wave ground-plane antenna on the two different bands.

LU 14 --

Mentor Discussion:

1. How long would each leg of a rhombic antenna be on 146 MHz if each leg was 3 wavelengths long?

2. Design a 3-element quad (reflector, driven element, and director) for 10-meters. Which way would you prefer to orient the spreaders - with the spreaders or wires oriented vertically and horizontally? Why?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. Did the antenna perform electrically as you expected when installed? If not, what did you observe that was unexpected?

b. How much change in signal strength was observed in the loop's null?

To experiment with the properties of loop antennas, a 2-meter loop will be constructed. Following the guidelines of Figure 7, make a single loop using the formula for the Driven Element length and a frequency of 146 MHz. Make the vertical spreader extra long by a foot or two so that you can use it as a handle. You may also attach the loop to an SO-239 so that a cable with connectors can be used as a feed line.

Connect the feed line to a radio and do a quick check of SWR to be sure the loop was designed properly. Minimum SWR may be 2:1, since the loop's feed point impedance will be approximately 100 ohms. The point of minimum SWR should be within the 2-meter band.

Locate a strong signal and try to peak and null it by turning the loop. Is it easier to peak or null the signal? Can you correlate what you observe while moving the antenna with the radiation patterns in the lesson? Try experimenting with reception using the loop on its third harmonic on 70 cm and try to observe the predicted antenna pattern on the loop's second harmonic.

LU 15 --

Mentor Discussion:

1. Listen to various noise sources on your receiver. Can you identify which are natural and which man-made?

2. Which of the receiving antennas in Figure 4 would you prefer to build? Why? What type of noise do you think it would remove best?

Construction Project (Optional):

If you undertake the construction project, report to your mentor:

a. How much difference in absolute signal strength did you observe between the two antennas for various signals?

b. When one antenna provided markedly better reception of the signal, were the absolute signal strength of the atmospherics higher or lower?

If you have access to a vertical low-band antenna, construct a dipole for the same band and mount it a few feet off the ground. Listen to both antennas when the band is open and compare the quality of the received signals from both antennas. Note the time and and the distance to the station when one antenna seems to be better than the other. Does the relative performance seem to favor one or the other at all times or just at certain times?

Browse the following Web sites and review some of the many variations on receive antenna designs.

Loop Antennas - http://www.imagenisp.ca/jsm/loop.html

Low-Band Receive Antennas - http://www.hard-core-dx.com

Tutorials and Articles - http://www.cebik.com/

EC-011 RF Propagation

Learning Unit 1

Student Activity:

Over the course of one or more days, listen for radio signals on at least 5 frequencies between 1 and 30 Mhz. Radio time signals make excellent choices because they transmit at the same power 24 hours a day. For example, you might monitor WWV at 5, 10, 15, 20, and 25 Mhz. Listen in the morning, afternoon, evening, and after dark on each frequency. Prepare a table showing how readable the signal was on a scale of 1 to 5, 5 being the most readable, and the signal strength on a scale of 1 to 9, 9 being the strongest. You could setup a table like this:

Frequency	Morning	Afternoon	Evening	Night
2.5 Mhz
5 Mhz
10 Mhz
15 Mhz
20 Mhz

Use this data to explain to your mentor how the signals varied with time of day and frequency.

Learning Unit 2

Student Activity:

Divide the HF bands into 2 MHz segments ranging from 2 to 30 MHz (2-4 MHz, 4-6 MHz, etc). Listen on each band in the morning, afternoon, evening, and night time and record whether you are hearing long or short distance stations or no stations at all. It helps to keep a table of your observations like this:

Band	Morning	Afternoon	Evening	Night
2-4 Mhz
4-6 Mhz
6-8 Mhz
8-10 Mhz
10-12 Mhz
12-14 Mhz
14-16 Mhz
16-18 Mhz
18-20 Mhz
20-22 Mhz
22-24 Mhz
24-26 Mhz
26-28 Mhz
28-30 Mhz

Using this information, explain to your mentor how different bands can be used at different times of the day over different distances.

Learning Unit 3

Student Activity:

Find out how high a glider might fly in the air and relate this to the areas of the atmosphere. Repeat this for the maximum altitude that an international jetliner might fly. Also consider the shuttle. This will help give an idea of the altitudes that are being talked about. There is no need to send this to your mentor.

Learning Unit 4

Student Activity

There is no activity for this unit.

Learning Unit 5

Student Activity:

Visit the SIDC (World Data Center for the Sunspot Index) website at http://sidc.oma.be/current/ri.html. Using their data, plot the sunspot activity for last month. Plot days along the horizontal scale and sunspot numbers along the vertical scale. The variation in the figures can be large even over the period of a month. Calculate the average for the month and check your answer against theirs on the website. Compare this information to the plot of the last 4 years of sunspot data at http://sidc.oma.be/html/wolfmms.html.

Elsewhere on the web site you will find a considerable amount of information on sunspots. The main page is at http://sidc.oma.be/index.php3. Look particularly at the latest forecasts and the weekly overview. Describe to your mentor what all of this means for propagation. Include a discussion of these questions:

1. Where are we in the current sunspot cycle?

2. What recent activity has there been on the sun? Have there been any noticeable propagation effects?

Learning Unit 6

Student Activity:

Listen on the bands above 14 MHz over a period of several days, and note the location and signal strengths of the stations heard. Note the maximum signal strengths heard using the system you used in the first lesson. There should be a noticeable drop for stations more than 3500 to 4000 miles away as two hops are required rather than one. You should also be able to see the effect of the directional pattern of the antenna and its takeoff angle as well. It will be helpful to record your observations in a table like this:

Report the results of your observations to your mentor. Address the following questions specifically:

1. Do you see any evidence of a multiple hops?

2. How did signal strength vary with distance? With direction?

Learning Unit 7

Student Activity:

Go to http://sec.noaa.gov/ftpdir/lists/iono_day/Wallops_iono.txt and download the ionosonde data for a 24-hour period. Note the differences between f_oE and f_oF₂, i.e. the critical frequencies for the E layer and F₂ layer, respectively. Estimate approximately what the maximum useable frequency might be for 0600 UTC, 1200 UTC, 1800 UTC and 2400 UTC (note the relationship given earlier to estimate the MUF from the critical frequency).

A very instructive way to look at this data is to save it on your PC and import it into a spreadsheet application and then chart it in different ways. For example, this chart was produced in March 2004 from ionosonde data showing f_oE and f_oF₂ vs time of day. It was done in Microsoft Excel by selecting the X-Y Scatter type of chart for the data.

Report your observations to your mentor. If you are unable to get original data, discuss the chart above.

Learning Unit 8

Student Activity:

1. On each amateur band from 1.8 to 30 MHz, listen for signals in the morning, afternoon, evening, and night time. Record, if possible, the location of signals you hear and their strength and readability. Also listen for the level of noise present on each band and for fading or other effects that impact signal reception. If possible, spend time listening to different signal modes (Voice, CW, Digital, etc) so you can see the effect of signal mode on propagation.

A convenient way to do this is to setup a table similar to that in LU1 and record your observations by using the same Readability/Strength system as before, but adding a number from 1-9 for noise (1=no noise, 9=noise so loud it masks all signals), a number from 1-5 to rate fading (1=none, 5=signal disappears), and if listening on multiple modes, a letter indicating the mode (C=CW, V=Voice, D=digital for example).

If you are really serious about learning to use propagation, then redo this exercise on a regular basis, comparing your observations over time and learning to recognize the correlations between the state of the sun, the state of the ionosphere, and the bands.

Report your observations to your mentor as a band-by-band summary of the propagation conditions on that band.

2. Go to the International Beacon project web site at http://www.ncdxf.org/beacons.html and look at the current data on beacons as observed at one of the monitoring stations. Also attempt to hear one or more of the beacons to compare with your data in activity 1 above. Report your observations to your mentor and discuss how this compares with the results of your own band studies in the first activity.

Learning Unit 9

Student Activity:

1. One of the very best sources of propagation information is NW7US's web site. Look at the current solar activity information on his page at http://hfradio.org/propagation.html. A look around this page will find many fascinating bits of information about propagation and solar activity and links to more. Describe current solar activity for your mentor and its impact on expected propagation.

2. Look over the propagation bulletins on the ARRL web site from K7RA at http://www.arrl.org/w1aw/prop/. Listen to different radio bands and compare what you hear with the predicted propagation. A good way to do is to listen to beacons and time stations like WWV. Keeping a log sheet like this can help:

Date	Time (UTC)	Frequency	Station	Signal

Do the actual band conditions reflect what you read in the propagation bulletins? If not, why not? Report to your mentor the results of your listening.

Learning Unit 10

Student Activity:

1. Locate the figures for solar flux, Ap and Kp. You can find them on the internet in a variety of places or by listening to WWV. Record these numbers daily for a period of time, at least a week, along with your observations of propagation conditions.

Date	Time	Solar Flux	Ap	Kp	Propagation Conditions

If these numbers are changing, a graph can be useful. Discuss with your mentor your evaluation of propagation and the likely future propagation conditions from your observations.

2. Visit some of the many sites that are dedicated to propagation information on the Internet. You can locate them by an online search or any other means. Some interesting sites can be found by starting with the ARRL's Technical Information Service page on propagation at:

http://www.arrl.org/tis/info/propagation.html

Other useful pages are NW7US' hfradio.org site:

http://hfradio.org/propagation.html

the DX Listener's Club solar page:

http://www.dxlc.com/solar/

and the Space Weather page at

http://www.spacew.com/

Review these and other available information and tell your mentor which one you think will serve your needs and interests best and why. There is no right answer since all of these sites will provide either directly or through links access to more information than you need. Focus on finding a site that provides what you need, but also access to other resources and information that can enrich your understanding of propagation.

Learning Unit 11

Student Activity:

Use whatever propagation prediction program you have, either a free program or a demo, and predict conditions for 3 times of day on three different bands from your location to three continents. For example, if you live in North America, you might predict conditions to a station somewhere else in North America, to South America, and to Europe. Do one prediction for day time, one for evening at sunrise or sunset, and one for night time. Tune into the bands at the predicted times and assess the conditions that you find by listening to the stations you can hear. Report to your mentor what you find and how good the correlation is between the conditions that you find and the predictions. If you find that the predictions don't match the conditions, explain as best you can why you think that might be.

Learning Unit 12

Student Activity:

Investigate the path of the gray line using a computer program like Geoclock or W6ELProp. Make an estimate of where you think you are likely to hear stations from using the computer program, then listen at dawn or dusk for a few days on a range of bands from 80 through 10 meters and identify any stations you hear. Report to your mentor your success or failure in hearing stations along the gray line. If you were unable to hear anyone, review the likely reasons why you think you couldn't hear anyone with your mentor.

Learning Unit 13

Student Activity:

Sporadic E is too unpredictable to base an assignment on, but based on the reading material, estimate the chance of Sporadic E occurring in your area over the next several days. Listen for signals above the MUF when you think it likely that Sporadic E might occur. Try to identify the location of the transmitter in any cases you observe and estimate whether or not you think you've observed Sporadic E propagation. Discuss with your mentor your predictions and observations.

Learning Unit 14

Student Activity:

Monitor weather maps over a period of several days to assess the likelihood of an improvement in tropospheric propagation conditions and to where they may occur. Listen to VHF and UHF frequencies if you can to confirm your predictions. Discuss your thoughts with your mentor, explaining what areas you think you could establish communications with from your area and what weather conditions make these conditions likely.

Learning Unit 15

Student Activity:

1. Monitor the Internet for high values of the A and K indices. If it happens during the course, listen for signs of auroral activity on 2 Meters. It is likely you will not be able to identify any auroral propagation unless you are near enough to the magnetic pole and have a well equipped station. Report any activity you are able to identify to your mentor.

2. Research one or more auroral events through some of the internet sites that carry propagation information or through reports in amateur radio magazines. Discuss with your mentor what it would require to take advantage of an auroral event such as those you've read about in terms of location and equipment.

Learning Unit 16

Student Activity:

During the next meteor shower, spend some time listening for signals from meteor scatter propagation. In order to know what to listen for, go to the meteor scatter web site at http://www.meteorscatter.net and listen to the sounds of meteor scatter communications. The direct link to the meteor scatter sounds page is: http://www.meteorscatter.net/msound.htm

The site has links to just about everything you might want to know about meteor scatter communications including the many software programs that can be used, like WSJT. Discuss with your mentor how you might set up to listen to meteor scatter communications and how you would know that they really are from meteor scatter propagation.

EC-012 Analog Electronics - Student Activities

LU 3

Design Problem:

In Figure 3, use the rules for combining series and parallel resistors to calculate the equivalent resistance inside the dashed line. Share the results with your mentor.

[Insert Figure 3 here]

Figure 3

Construction Project (Optional):

If you have ac instrumentation:

LU 4

Design Problem:

Use a 1N4732 Zener diode to supply a 4.7 V regulated voltage. The power supply voltage, V_CC, is 12 V. Limit the Zener power dissipation to 100 mW. (the 1N4732 diode is rated for 1 watt dissipation) Share the results with your mentor.

Construction Project (optional)

Construct the Zener voltage regulator you designed (omit the noise filtering capacitor). Test it without a load and be sure that the current through R_LIM is what you expected. Add a load resistor of 1 kohm to draw 4.7 mA. Is the voltage across the Zener still 4.7 V? Use load resistors of 470, 330, and 220 ohms to see what happens to V_Z as load current exceeds the maximum allowed.

LU 5

Design Problem

You are building a power supply using a transformer whose center-tapped secondary supplies 25.2 V_rms. (That's 12.6 V_rms­­ for each half of the secondary.) The average load current will be 100 mA. Assuming that you are using the full-wave, center-tap rectifier and that the input voltage's frequency is 60 Hz:

a) Calculate the minimum filter capacitor value for a ripple voltage of 0.5 V pk-to-pk.

b) What is the PIV rating required each of the diodes?

c) How much power will each diode dissipate at full load?

Share the results with your mentor.

Construction Project (optional)

Because function generator outputs usually have a ground-referenced output, we will only test the half-wave rectifier. Build the half-wave circuit of Figure 2 using a 1N4007 diode and a 3.9 kΩ load resistor. Connect your voltmeter across the output load resistor.

Set the function generator to output a sine wave of 5 V_pk (3.5 V rms on the voltmeter's ac scale) at 1 kHz. The voltmeter will show about 1.3 V dc across the load. If you have a 'scope, you will be able to see the load voltage pulsing on every positive half-cycle of the input sine wave. Note that the diode doesn't conduct for exactly one-half cycle. The 0.7 V forward drop causes the diode to conduct for slightly less than one half-cycle.

Now connect a 1 mF capacitor with at least a 10 V rating in parallel with the resistor with the positive terminal connected to the diode's cathode as in Figure 2. The voltmeter will now show a load voltage of about 3.6 V dc because the capacitor stores energy during the half-cycles when the diode isn't conducting. The 'scope will show the load voltage as a series of short charging ramps (as the capacitor charges through the diode), followed by long discharging ramps (as the capacitor discharges through the resistor), as in Figure 2.

Experiment by trying different input voltages, load resistors, and capacitors. If you have a function generator with a ground-independent (or floating) output, try building the full-wave rectifier circuit in Figure 1.

LU 6

Design Problem:

None.

Construction Project (Optional):

None-be sure you review the lesson and understand how the two types of transistors work. The supplemental reading is recommended if you are having difficulties or you may consult your mentor.

LU 7

Design Problem

Follow the procedure in the lesson to design a CE amplifier with the following characteristics: |A_V| = 4, I_CQ = 5 mA and V_CEQ = 6 V, V_CC = 12 V. Assume the transistor's b is 200 and V_BE = 0.7 V. When you are finished, substitute the closest standard resistor values to your calculated values. Share the results with your mentor.

Construction Project (Optional):

Build the amplifier using a 2N3904 transistor and 10 mF coupling capacitors. Connect the power supply only after double checking all connections, especially the transistor leads.

1) Use a voltmeter to measure the dc voltage from collector to emitter (it should be about 6 V), from base to emitter (0.6 -- 0.7 V), and from collector and emitter to ground (7 V and 2 V, respectively)

2) Replace R1 with the 100 kΩ pot set to about 22 kΩ. Confirm that all dc voltages remain about the same. Connect the voltmeter between collector and ground and observe what happens to V_CE as R1 is decreased and increased (raising and lowering base current). Use Ohm's Law to determine what is happening to collector current as you adjust R1. Reset the pot to 2 kΩ.

If you have the equipment, proceed to the ac measurements below.

3) Set the signal generator to output a 1 kHz sine wave at 200 mV pp, then connect it to Cin. If you are using a 'scope, you should see a sine wave at the output of Cout with an amplitude of about 1 V pp and inverted from the input. (A voltmeter measuring ac voltage will show values of 70 mV rms at the input and 350 mV rms at the output--a gain of 5.)

4) Adjust R1 in each direction and observe the output signal with the oscilloscope. As you lower the collector current, you will begin to see the output waveform clip on positive peaks as the collector current is cut off. Raising collector current will eventually result in distortion on negative peaks as the transistor enters saturation.

5) Return R1 to 22 kΩ and increase the input signal to observe distortion on the output. If you are using a voltmeter, note that the rms output stops increasing as the signal becomes clipped.

6) Turn down the input signal as far as possible. Connect a third 10 mF capacitor across R_E. (Connect the negative side of a polarized capacitor to ground.) Slowly increase the input signal and observe the new gain of the circuit. By bypassing R_E, the dc operation of the circuit is unaffected, but now the emitter circuit is effectively grounded for ac signals. Gain is now only limited by the internal impedance of the transistor emitter.

7) Now that you have a working circuit--experiment with it!

LU 8

Design Problem

Design an EF amplifier with the following characteristics: V_CC = 12 V, Q-point of I_CQ = 2.5 mA and V_CEQ = 6 V. Assume a b of 125 and use 0.7 V for V_BE as usual. Use the closest available standard resistor values. Calculate Z_IN and Z_OUT using the same assumptions as in the example. Share the results with your mentor.

Construction Project (Optional):

Build the circuit you designed, constructed similarly to the photo in Figure 2. Input should be on one side and output on the other. Use a star ground for voltmeter, signal, and 'scope connections. Using a single wire stuck into a ground terminal works pretty well.

1) Use a voltmeter to measure the V_CEQ from collector to emitter (it should be about 6 V), V_BE (0.6 ~ 0.7 V), and from emitter to ground (6 V).

2) Replace R1 with a 100 kΩ potentiometer, set to 15 kΩ. Attach a 1 kΩ resistor from the output of C_OUT to ground as the load, R_L.

3) Set the signal generator to output a 1 kHz sine wave at 1 V pk-pk, then connect it to C_IN. If you are using a 'scope, you should see a sine wave across the 10 kΩ output resistor with an amplitude of about 1 V pk-pk, in phase with the input. A voltmeter will show values of 700 mV rms at the input and at the output. Increase the input voltage until the largest undistorted output is obtained-record input and output voltage.

If you have the equipment, proceed to the ac portion of the experiment.

4) NOTE: The high EF bandwidth can lead to oscillation at several hundred kHz or higher, if you're not careful. This instability is visible as the "fuzzy" or "lumpy" oscilloscope traces. Those of you using voltmeters only might see intermittent or jumpy ac signal voltages. Sometimes, just moving the leads around will cause the oscillation to start and stop, so don't be afraid to experiment.

5) Set the input signal to 5 V pk-pk. Adjust R1 higher and lower while observing the output signal with the oscilloscope. As you lower the collector current (V_B decreasing), you will begin to see the output waveform clip on negative peaks as the collector current is cut off. Raising collector current will eventually result in distortion on positive peaks as the transistor enters saturation (where it can no longer increase collector current).

6) If input power is (V_IN)²/Z_IN and output power is V_OUT²/R_LOAD, compute the power gain of the amplifier for the maximum undistorted values of input and output voltage. Compare with the estimated value Z_IN/R_L.

7) With the input at 1 V pk-pk, decrease and increase the frequency to find the points at which the output voltage drops to 70 % of its value at 1 kHz. These are the lower and upper limits of the amplifier's frequency response.

8) Change the input waveform to a square wave at the highest frequency your generator can reach. See if you can see any differences between the input and output waveforms as in the photo.

LU 9

Design Problem:

Design a common-base amplifier with a voltage gain of 20 using a 2N3904 transistor. Assume h_ie is 1 kW and b is 150 and that no load is connected at V_OUT. Use a 12 V power supply and design the biasing network for 2 mA of collector current and a V_CEQ of 6 V. Share the results with your mentor.

Construction Project (Optional):

Build the amplifier you designed in the design problem, using 10 mF coupling and bypass capacitors. (Pay attention to the polarity if you use tantalum or aluminum electrolytic capacitors.)

Test the amplifier and see if you get the voltage gain you expect. Add a load resistor equal in value to R_C. Voltage gain should be halved--is it? Experiment with the load resistor value.

LU 10

Design Problem:

Design a driver circuit based on the TIP31 to drive a 25 W load from a 12 V dc power supply. Use the table of TIP31 parameters presented earlier in the lesson. Calculate the necessary value of R_G and the power dissipated by both the load and the transistor. Share the results with your mentor.

Construction Project (Optional): Build and test the circuit you designed.

LU 11

Design Problem

Design each of the following circuits:

1) First-order high pass filter, f_C = 100 Hz, with R = 10 kW. Calculate the filter's attenuation at 50 Hz, 25 Hz, and 10 Hz.

2) Parallel tuned circuit, f_O = 100 kHz, with L = 1 mH. If R = 10 kW, estimate the circuit's Q and bandwidth.

Share the results with your mentor.

Construction Project (Optional):

Build the parallel tuned circuit and measure it's frequency response (magnitude and phase) from 10 kHz to 1 MHz or as high as your signal generator and voltmeter can measure. (If you can not measure reliably at 100 kHz, increase L by a factor of 10 and recalculate the Q and BW.) Identify the upper and lower cutoff frequencies (measure the frequencies at which the output voltage is 70 % of the input voltage) and calculate BW and Q. Compare to your predicted values and discuss the results with your mentor.

LU 12

Design Problem:

Design a summing amplifier to have a gain of --1 for each input by setting all three resistors (R₁, R₂, and R_f) to 10 kW. You will need a ±12 V power supply to test this amplifier configuration. Share your results with your mentor.

Construction Project (Optional):

Build the circuit as shown in Figure 4. Supply a 1 V pk-pk, 1 kHz sine wave to input 1. Short input 2 to ground. Verify on your voltmeter or 'scope that the gain for input 1 is -1. Move the sine wave input to Input 2 and verify that it is working, too.

[Insert Figure 4 here]

Figure 4

Connect a 1 kW potentiometer to input 2 as shown in Figure 4 with the sine wave connected to Input 1. Vary the potentiometer while watching the output on your oscilloscope or voltmeter set to measure dc voltage. You will see the inverted sine wave from input 1 shifted up and down as the dc level at input 2 changes.

Experiment by altering the value of either input resistor and R_f to observe the effect on the gain of signals. Replace R₁ or R₂ (or both) with a 10 kW potentiometer and vary the channel ratios independently. Congratulations, you've just built a 2-channel mixer!

LU 13

Design Problem

Select any of the filter types covered in this lesson and design an audio filter with a cutoff frequency of 5 kHz or less. You should be able to calculate the gain, cutoff (or center) frequency, and damping factor (or Q). Share the design with your mentor.

Construction Project (Optional):

Build the circuit you just designed and use your function generator and voltmeter or 'scope to measure its frequency response. Compare the gain and cutoff (or center) frequency to what your design predicted. Share the results with your mentor.

All this measuring is fine, but it's a lot more fun to actually use your circuits for a practical purpose. Figure 6 shows how to route your rig's received audio through the filter circuit so that you can hear the effect of the filter using headphones from a portable music player. Set your rig to use its widest filter (usually 'AM') and then listen to the filter output. The op-amp can't drive a very big load, so keep the rig's audio output level low to avoid distortion.

[Insert Figure 6 here]

Figure 6

LU 14

Design Problem

Modify the monostable design example to an astable circuit by dividing R into two approximately equal resistors whose sum is close to 91 kΩ. Calculate the expected pulse repetition frequency (PRF) and duty factor of the output. Share the results with your mentor.

Construction Project (Optional):

Build the astable circuit and measure the PRF and duty factor. The total cycle time should be close to 1 s. If you have a stopwatch, count 10 or more cycles and average them for a good cycle time measurement. Compare the frequency and duty factor to your design values. Experiment with different combinations of R1 and R2 to observe the effect of their ratio on duty factor. (Keep R₁ greater than 1 kΩ to avoid overloading the discharge transistor.) If you have an oscilloscope, watch the capacitor voltage on one channel and the output voltage on the other.

LU 15

Design Problem

Change the fixed-voltage regulator of the design example in Figure 1 to a variable regulator as in Figure 1(a). If the resistive divider consists of a pair of 4.7 kΩ resistors, what will the output voltage be? Move the divider to reduce the op-amp setpoint as shown in Figure 1(b). What will the output voltage be? Share the results with your mentor.

Construction Project (Optional):

Build the linear regulator, using a 1 kΩ load resistor and a 12 V dc power supply. When you put the circuit together, take particular care to connect the op-amp's inverting (-) and non-inverting (+) terminals correctly. Check to be sure the Zener diode and output voltages are almost identical and close to 5.1 V. The output of the op-amp should be about 0.7 V greater than the load voltage. How much power is the transistor dissipating? The load resistor?

Vary the input voltage up and down by 3 V. What is the effect on load voltage? How much can the input voltage be reduced before the load voltage starts to change dramatically? Watch the op-amp's output voltage to see at what input voltage it can no longer supply adequate drive to the transistor.

Create an adjustable output regulator by replacing the two 4.7 kΩ resistors with a 10 kΩ potentiometer. Keep the 0.1 μF capacitor at the midpoint of the divider. Share the results with your mentor.

LU 16

Design Problem

Take a close look at one or more of the 741 op-amps you have on your workbench. Type in "[part number] data sheet" to a Web search engine, find the manufacturer, and download the part's data sheet. Compare the bandwidth (also called "gain-bandwidth product") specifications with those of the LM741. Which are faster and slower? By how much? Are there conditions or notes that apply to the specified values? How do they compare from manufacturer to manufacturer. Share your observations with your mentor. Share the results with your mentor.

Construction Project (Optional):

Connect an op-amp as an inverting amplifier with a gain of 10 and supply it from at least ±6 V. (R_f = 3.3 kΩ and R_in = 330 Ω will work nicely) Input a 0.5 V pk-to-pk 10 kHz square wave into the amplifier and observe the output with an oscilloscope. Trigger the 'scope on the input square wave and increase sweep speed while watching the output waveform. If you have a dual-trace 'scope watch both the input and the output. Increase the sweep speed until you can see the output's rising and falling edges--they should be somewhat slower than the input signal. Measure the time it takes for the output to change from minimum to maximum voltage. Divide the total output voltage swing by your measured time. This is the amplifier's slew rate. Compare the slew rate you measure with the specified value for the part. Does it meet spec? Discuss with your mentor.

EC-013 Digital Electronics - Student Activities

Design Problem & Construction Project (Optional):

There is no formal exercise for this lesson. Spend your time acquiring the necessary components for the upcoming exercises. If possible, acquire a CD4011 Quad NAND gate IC and download its data sheet from <http://www.ee.washington.edu/stores/>. (Click on “Library of Data Sheets” and then “Logic CMOS - CD4xxx series” to find the list of CD4000-series data sheets.) Review the connection diagram shown at the bottom of the first page. Learn to recognize where pin 1 is on the physical device and become familiar with plugging it into the prototyping board.

LU 2

Design Problem

Determine the truth table for the circuit shown in Figure 3 and share it with your mentor.

[Insert Figure 3 here]

Construction Project (Optional):

Look up the data sheets for the CD4011B (NAND), CD4077B (Exclusive-NOR), and CD4049B (Inverters) at <http://www.ee.washington.edu/stores/> and obtain one of each type of IC. Connect the circuit for the design problem and power it with +5 V. (You can construct an XOR gate by connecting an inverter to the output of an exclusive-NOR gate.)

Verify your truth table by connecting the inputs to +5 V for a 1 and to ground for a 0. Use the LED tester circuit shown in Figure 3 if you don’t have a logic probe.

Since you’ll be making lots of digital circuits, I recommend that you make up a dozen or so LED testers. That way, you can wire up one of these probes to each gate output if you like–it’s fun to watch the LEDs change as you change the inputs. Then you can use the logic probe to check individual points in the circuit.

LU 3

Design Problem

Think of a “word problem” around your home or shack that involves combinations of digital signals (such as an ON/OFF signal or switches that are OPEN or CLOSED, represented by 1 and 0). The problem should have at least four inputs and one output. Add one signal that acts as a master over-ride and causes the output signal to be TRUE regardless of all other input signals. Write one or two sentences that describe the problem in IF-THEN terms, using AND and OR and NOT. Convert the sentences into a logic equation and a truth table. Share your results with your mentor.

Construction Project (optional):

Build the circuit using CD4001 NOR gates and CD4011 NAND gates.  Test it and share the results with your mentor.

LU 4

Design Problem

Design a circuit using gated latches made from NOR gates that would capture the state of two input data signals whenever a pushbutton switch was closed, generating a clock signal. Use a NOR gate to make the switch debouncer circuit from the previous lesson. Use NOR gates to combine the output of the latches so that when any of them is HIGH, the switch debouncer NOR gate is prevented from generating a HIGH clock signal. Share your results with your mentor.

Construction Project (Optional):

Construct the circuit you designed. This is the basic circuit that can determine which of two contestants pushes a switch first. Add an LED tester to the output of each latch (as shown in the first lesson) so that when the latch output is HIGH, the LED lights.

You can simulate the data signals with jumpers to the power supply voltage or you can use pushbutton switches. Remember to add a 10 kΩ pull-down resistor on each input so that when the switch is open, the input to the latch is kept LOW.

LU 5

Design Problem:

Design a circuit that uses a pair of D-type flip-flops to divide an input signal of frequency f by four, creating an f/2 and f/4 signal. Use logic gates such as NAND or NOR to combine the flip-flop outputs, creating a positive pulse train with frequency f/4 and a 25 % duty factor. Share your results with your mentor.

Construction Project (Optional):

Build your design and use a slow input square wave of 1 Hz so that you can observe the dividing and gating actions with LEDs. Try to solve the problem with different combinations of gates to “move” the output pulse to different combinations of inputs.

LU 6

Design Problem:

Create a symmetric divide-by-14 circuit by using a CD4018 divide-by-N counter configured to divide by 7 and one section of a CD4013 dual D-type flip-flop. Use two sections of a CD4011 to form an AND gate with its inputs connected to the CD4018’s \oQ¯₃ and \oQ¯₄ outputs and its output connected to the CD4018 IN connection. The LOAD (or PRESET ENABLE) and RESET of the CD4018 should be tied LOW with the JAM inputs and remaining \oQ¯ outputs left unconnected. The data sheet of the CD4018 can be obtained at <http://www.ee.washington.edu/stores/> showing all pins and truth tables. Share your results with your mentor.

Construction Project (Optional):

Build the circuit you designed. Input a 1 Hz pulse train to the CD4018 CLOCK input. Use an LED tester, the logic probe, or your ‘scope to observe the CD4018 outputs and the output of the CD4013 flip-flop. Verify that your circuit divides by 14 and that the output is symmetric. Once you have your circuit working, you can change the AND gate inputs to create other divisors as shown in the CD4018 data sheet on page 5.

LU 7

Design Problem:

Create a latched counter by combining the CD4024 7-bit ripple counter with a 74HC373 latch/buffer. (One of the latches will remain unused). The CD4024 advances its count on the negative-going edge of the input clock signal. If you connect the clock signal to both the counter and latch enable inputs the counter output will not be stable when the data is latched into the ‘373. What could you do to the latch enable signal to capture the data when it is stable? Share your results with your mentor.

Construction Project (Optional):

Build the circuit you designed in the design problem. Set the function generator to output a 5 V, 100 Hz square wave. Be sure to tie the 4024 Reset signal LOW. Use LED testers to observe the output of the latch.

Start with the ‘373 output enable signal LOW so that the outputs are always enabled. Get the counter running so that you can see the LEDs changing. What happens when you disable the ‘373 outputs by tying the output enable signal HIGH?

Re-enable the ‘373 outputs and experiment with the latch enable signal to see if there is any difference in behavior when the same signal is used for both counting and latching.  Experiment by increasing the input pulse frequency, as well.

LU 8

Design Problem:

Design a circuit that takes a CD4518 BCD up-counter’s output and displays it as one of 10 LEDs by using a CD4028 BCD-to-Decimal decoder. Share your results with your mentor.

Construction Project (Optional):

Build the circuit you designed in the design problem. Use a 1 Hz square wave or pulse train output from your function generator so that you can see the counter working. Put an LED tester on each output of the CD4518 so that you can compare the counter output to the decimal decoder output.

LU 9

Design Problem

The National Semiconductor DAC0808 <http://www.national.com/ds/DA/DAC0808.pdf> is a simple, 8-bit digital-to-analog (D/A) converter that uses whatever binary data is present at its input to control a set of resistors and switches. The DAC0808 has no latching function at its data inputs, so design a circuit using a 74HC373 that would hold the DAC inputs steady between write cycles. Sketch the timing diagram for performing a write cycle to the 74HC373. Share the circuit with your mentor.

Construction Project (Optional):

None

LU 10

Design Problem

Design logic circuits that implement the ‘allow-eight-pulses-and-stop’ and the ‘count-eight-pulses-and-stop’ functions shown in Figure 2 and 3. Use a CD4018 counter, NAND/NOR gates, and inverters as necessary. Share your results with your mentor.

Construction Project (Optional):

Build either of the circuits and test them by applying a slow pulse train. Use LED testers to be able to observe the circuit by eye.

LU 11

Design Problem:

Configure an 4018 counter so that it will translate successive closures of a momentary switch into a three-bit binary value. Connect the counter outputs to a 74HC138 so that one of eight individual signal lines is activated on each count. The circuit should cycle through the binary value and individual signal lines in eight switch closures. I.e.—the circuit should not count to sixteen, ignoring a second set of eight closures. Share the results with your mentor.

Construction Project (Optional):

Build the circuit you designed and report to your mentor. If you have time, experiment with circuits that use a switch closure to V_CC instead of ground. Substitute an optical or magnetic switch (such as a security system sensor) for the switch closure.

LU 12

Design Problem

Design a circuit that uses a bidirectional red/green LED to generate a variable color from red through yellow through green. Include an off/on control signal.  The color should change either in steps or continuously. Share the results with your mentor.

Construction Project (Optional):

Build the circuit using a common-cathode bi-color diode (such as the LT0362-25-D61 from Jameco) and experiment with it. Was it as bright as you expected? Is the brightness even for all colors?

LU 13

Design Problem:

None

Construction Project (Optional):

Obtain a 74LS04 hex inverter. Connect a 1 kW pull-up resistor to its input with a switch or jumper that can make a momentary connection to ground. Connect its output to a transistor level shifter as shown in Figure 4b. Connect the output of the transistor to one input of a CD4069 inverter and use an LED tester on its output.

Use +5 V for the power supply for all three devices—74LS04, transistor, and CD4069. Confirm that switching the 74LS04’s input to ground causes its output to go HIGH, the transistor output to go LOW, and the CD4069’s output to go HIGH.

Leave the ‘LS04 powered from +5 V. Obtain a 9 V battery or some other source of 9 to 12 V power. Run the transistor and CD4069 from the higher voltage. Again, confirm that switching the 74LS04’s input to ground causes the CD4069 output to change.

Now return the transistor power supply voltage to +5 V. Does the CD4069 output still respond to grounding the input of the 74LS04? Share the results with your mentor.

LU 14

Design Problem

Look up the data sheet for the PIC1400 microprocessor at <http://ww1.microchip.com/downloads/en/DeviceDoc/40122b.pdf>. Read the first page of the data sheet and answer the following questions:

1)      What is the maximum clock frequency for the processor?

2)      How many words of internal EPROM memory does it have?

3)      What kind of serial interface does it have?

4)      How many parallel I/O lines does it have?

5)      Name two of the analog interfaces it has.

Share the answers with your mentor.

Construction Project (Optional):

None

LU 15

Design Problem

Figure 4 shows the schematic for an 8-bit voltage ramp generator that uses a CD4040 12-bit ripple counter as its DAC. The input to the counter should be a square wave from a function generator. Add a connection to use the 9^th output bit to reset the counter, making it an 8-bit counter.

[Insert Figure 4 here]

An 8-bit ramp voltage ramp generator circuit

If the counter is operating from +5 V and assuming that the outputs are also +5 V, calculate the voltage across the 1 kW resistor when the output value is 00000001B, 00010000B and 10000000B. Including the voltage drop across the diode, the current through each of the counter output resistors is 4.3 V/(R + 1 kW). The current through the 1 kW resistor is the sum of all currents through the output resistors. Share your schematic and calculations with your mentor.

Construction Project (Optional):

Construct the ramp generator and operate it with a 1 kHz square wave input. Synchronize your oscilloscope to the counter’s 9^th-bit reset signal and adjust the sweep speed so that you can see a complete ramp. Observe the steps carefully and compare them to your calculated values. Are the steps clean or are there transients at the edges? Are the steps uniform? Share your observations with your mentor.

LU 16

Design Problem

Determine how much current you can draw from a CD4001 output with a power supply voltage of 5 V and still keep V_OH above 4.6 V. (Assume 25 °C temperature and use the typical values for I_OH.) Measure the forward voltage drop across the LED in one of your LED testers while it is connected from V_DD to ground. Use Ohm’s Law to calculate the minimum value of resistance the tester can have if the available voltage is V_DD - V_LED. Share your results with your mentor.

Construction Project (Optional):

Construct an LED tester with the closest available value of resistance to the minimum calculated above. Connect it to a CD4001 so that it is ON when the CD4001 output is HIGH. Verify that the output voltage when HIGH is at or above 4.6 V. Reduce the value of the LED tester resistor in steps and measure the output voltage. What is the output current when V_OH drops below 4.6 V? (Use Ohm’s Law by measuring the voltage drop across the resistor and dividing by R.) How does this compare with the typical value? Share the answer with your mentor.