Last time, I described how embarrassed I was not to have tried QRP PSK31 yet. This month I describe how I did it and how you can join in the digital QRP fun.

Digital Modes

For a quick review of digital modes visit my last column. Although this edition will primarily focus on operating PSK31, many of the hints from this column apply to a wide variety of "sound card" modes. As a lot of QRP enthusiasts (and even some QRO ops) have discovered over the past few years, PSK31 seems like it was made for QRP. It's so efficient that even DX QSOs are possible with low power and/or modest antenna systems on both ends of the contact.

The front of the Ten Tec Argonaut-V gives no clue about the handy feature for PSK operations available on the radio's rear apron.

The rear of the Argonaut-V shows features that make PSK setup quick and easy. Aux 1, a five-pin DIN socket (A) provides both input and output. A cable with a 5-pin DIN plugs into the radio. The other end of the cable (C) provides individual connections for Audio In, Audio Out, Push-to-Talk and Ground. The cable is available directly from Ten Tec, or can you build your own.

The 80 Meter Warbler transceiver design originally appeared in the NJ QRP Club's QRP Homebrewer magazine. It was dubbed "The Warbler" for PSK's characteristic two-tone warbling sound, as well as for the club's state bird (the mosquito!). The design was subsequently presented in the March 2001 issue of QST.

Setting My QRP PSK31 Station

There was no problem finding a computer with a sound card in my house (my day job is computer support, and my son majors in computer science). Next, I needed a radio. I had a few choices, but the fact that my Ten Tec Argonaut-V already had a cable wired for use with sound card modes made it an easy decision. With most radios, you will likely need a rig-to-sound card interface device. Again, the Argonaut was my top choice, as no interface is required--although some operators feel more secure by adding a level of isolation with an interface.

The final part of the picture was the software. Again, I took the easy way out by using PSK31 Deluxe (part of the excellent, free Ham Radio Commander suite.) Using PSK31 Deluxe meant I could handle the transmit switching (PTT) with the same interface cable used for rig frequency control. Depending on your rig and software, you may need to have a dedicated serial port and cable to key the rig. In some cases you can operate in a pseudo-VOX mode (ie, using the PSK31 audio signal from the sound card to switch your radio into transmit).

Operating my QRP PSK31 Station

After everything was assembled (including a few last minute RCA-to-mini stereo connector adapters), I was finally ready to try my hand at PSK31 QRP style. As with any mode--new or otherwise--I followed the "Golden Rule" of listening before transmitting. This is an especially good idea when you are only somewhat familiar with the mode in question. PSK31 Deluxe is one of the many digital-mode software packages that use a waterfall display for displaying and tuning signals.

One big change I had to get used to when operating PSK31 was not using the rig's tuning knob to tune in individual signals. Instead, you use the tuning knob to tune to the general area of the band where other PSK31 operators tend to congregate (eg, 14.070 MHz is the gathering point on 20 meters). The waterfall displays a swath of spectrum, and you "tune" by using your PC's mouse to click on a promising vertical signal stream (in essence, you are tuning to a frequency that should be within your radio's SSB transmit audio passband).

If you are successful, the software will begin to display a stream of text from the transmitting station. Many programs have the capability to actually "jump back" and copy a signal that was sent even before you actually clicked on the stream! Once you're sure everything is working and you're successfully receiving signals, it's time to get ready to transmit.

Another big change you'll want to make (if you don't already routinely run QRP) is turning down the power on your radio. Utilizing a dummy load, confirm that your sound card output level is correct and that your rig's microphone gain has been set so you're not overdriving your rig (typically, the audio level should be left at the point where your rig's ALC just starts to kick in). Once you have the sound levels set properly, you need to check that your rig can switch from receive to transmit and back to receive.

A Quick Digression on Audio Levels

Since you're actually "tuning" within your transceiver's audio passband when you click on the various streams of the waterfall display, going too far one side or the other of the center frequency, say 14.070 MHz, might cause your transmitter's output power to change.

For example, in the vicinity of the center frequency--the frequency you have your tuning knob set to--your power output might show as 5 W. But you might see the power drop off when transmitting on a frequency to the extreme left or right of center (we're not talking politics here). This is because you're approaching the upper or lower "rolloff" points of your transceiver's transmit audio passband (typically 2.7 kHz or so for SSB). A transceiver's ability to maintain the same audio level at these outer limits (ie, from what it can generate nearer to the center frequency) may vary from rig to rig, and the power output may roll off accordingly.

The quick remedy is to crank up the transmit audio level to compensate, but you also can retune with the tuning knob to put the desired signal closer to the center of the waterfall's passband.

Ready to Transmit!

Finally, before transmitting or attempting to make your first QSO, get familiar with the features of the PSK31 software you've chosen to use. You should know:

• which window to type in.
• how to switch from receive to transmit (and back to receive).
• how to use the type-ahead buffer (especially if your typing skills are a little rusty).
• how to preload information into macros (used to easily send "canned" information such as your call sign, QTH, name etc at a single keystroke).

When you're ready, get your feet wet by answering a CQ. Warning: You might even get that same nervous rush that you felt when you grasped that straight key for your first CW QSO. Just as in that first CW QSO, you may worry about not being able to remember how to send (type, in this case) or being able to do it rapidly enough.

But just as it was when you made your first few QSOs, in a very short time you'll get comfortable with the whole idea and it will become second-nature. Good luck! I hope to meet you soon on PSK31--QRP of course.

The ARRL Web site has additional information on PSK31 on its Technical Information Service (TIS) pages.

Reader Feedback and Author's Comments

Among the e-mails following my last column was one from Tom, N3IJ. He wrote, "PSK31 does not require 'a radio capable of sending and receiving SSB.' I've had good results with one of Dave Benson's PSK20s: 30 countries and 35 states despite intermittent activity and a bad antenna." The PSK20 is one of a series of QRP radios designed specifically for PSK operation. The descendents of the original 80 Meter Warbler, the PSK Series from Small Wonder Labs are available in 40, 30, 20 or 10 Meter versions.

Thanks for all your e-mails. I really enjoy the feedback and welcome your comments and suggestions.

Editor's note: Anthony Luscre, K8ZT, an ARRL Life Member, lives in Stow, Ohio. He has worked in the field of medical microbiology for 18 years and is now a Technology and Computer Coordinator for a local school district. Luscre is an avid QRP operator having earned DXCC, WAS and WAC using no more that 5 W output. Readers are invited to contact the author via e-mail, k8zt@arrl.net or visit his Web site.

Previous: New Foundation License, Amateur Regulatory Changes Introduced in Australia

Next: ARRL 2005 Holiday Toy Drive Kicking into Gear