 |
 |
|
|
|
|
|
|
||||||||||||||||||
|
|
|||||||||||||||||||
|
|
|||||||||||||||||||
|
|||||
 Previous: White House Greets Amateur Radio Operators |  Next: Florida Man Convicted in Deliberate Interference Trial |
By Gary Hoffman,
KB0H
Contributing Editor
June 20, 2002
I am still in the early stages of the HF game--still experimenting, still learning, and still not sure I know what I'm doing.
Every new ham has considered, at least briefly, working the high frequency (HF) bands. I don't recall exactly when I decided I'd like to try it myself, but even then I knew it wouldn't be like operating on 2 meters. All I needed to operate on 2 meters was a hand-held transceiver. Working HF would require... well, a bit more.
I am still in the early stages of the HF game--still experimenting, still learning, and still not sure I know what I'm doing. Nevertheless I thought I'd share my HF chronicles with you. Let me take you back to the beginning: Setting up my first HF antenna.
They say that an ideal HF antenna is a dipole suspended far above the ground. A very long dipole suspended way above the ground. I live in the suburbs. My property is not all that large. My neighbors are friendly enough, but I doubt any of them would allow me to erect tall towers in their back yards. And then there is the matter of a major international airport just a few miles away. What I'm trying to say is that the perfect dipole antenna was simply not an option for me.
 SWR meter: Just owning one of these things made me feel like a real ham. [Photos by the author] |
Since putting up an ideal HF antenna is out of the question for many hams, a lot of compromise antennas have been developed. The variety in the designs and costs of these antennas is overwhelming. Lesson number one when you decide to operate on the HF bands is that you will learn something about antennas--whether you want to or not.
I spent a long time thinking about HF antennas. I read books on the subject, but they assumed that I had a great deal of prior knowledge. I talked to experienced hams, but the technical jargon they used went right over my head. I consulted my Elmer, but even he gave me an answer that was no help. "It depends on what you want to do," he said.
It seemed that there was no one, correct HF antenna. It all depended on an infinite number of variables starting with "What are your goals?" Well, being brand new to the HF bands, I didn't have any goals. I didn't know what specific band would attract me. I had no idea which mode I would eventually use. Would I get into DXing? Would I try CW? Would I enjoy contesting? I just didn't know.
I eventually did buy an HF antenna. I bought an MFJ-1796--a half-wave vertical (see "Product Review," QST, Nov 1994)--based on the following criteria:
 Do the words "Some assembly required" strike terror in your heart? |
Some Assembly Required
When it arrived I opened the box, read the instructions, said "Holy Cow!" and put it back in the box. Do the words "Some assembly required" strike terror in your heart? Okay, you get the picture. I mumbled and groaned about it for months until Nancy told me to either put up the antenna or shut up about it. I think she was hoping for "shut up."
You see, it was not just a matter of assembling the antenna--it had to be tuned. All antennas have a resonant frequency. An analogy is the phenomenon observed when you rub the rim of a wine glass with your finger. At a certain pressure and speed, the wine glass will hum. You have excited its resonant audio frequency. Antennas are like that. You have to alter the antenna so that its resonant radio frequency is within some Amateur Radio band. And yes, Gary's First Law applies--It Takes a Special Tool.
Before assembling the antenna, I had to buy the Special Tool--a standing wave ratio (SWR) meter. Just owning one of those things made me feel like a real ham!
Although assembling the antenna was labor-intensive, it wasn't complicated. Tuning the antenna was another matter. The antenna had to be mounted on a short mast and held in place by one person (Nancy) while a second person (me) operated the SWR meter and wrote down readings. The actual tuning consisted of calculating how far out-of-band the antenna was, then laying it down and snipping off parts.
 I told Nancy, "Of course ham spouses climb roofs." She took this picture to prove she was up there. |
We spent an afternoon doing this. Remember, it was a multiband antenna, and had to be tuned separately for each band. The antenna was an unwieldy affair, too, and raising and lowering it so many times inevitably resulted in it being dropped--several times. I spent a lot of time straightening bent parts.
Once the antenna was assembled and tuned, we (yes, Nancy, too) climbed onto the roof of our house and hauled the antenna up after us. We marched it over to its stand, dropped it one more time for luck, attached the feed line and raised it into position. A few minutes later it was in place and fastened. Other than getting down from the roof in one piece, the hard labor was over. It was a strange and exotic-looking antenna--and if you looked at it with a pair of binoculars, you could still see the bent parts.
Although the heavy labor was over, there was more to do. You see, once the antenna was mounted on the roof its resonances changed. Now it was out of tune for a couple of bands. Well, it was going to stay right where it was. We were not going to mess with it again unless someone volunteered the services of a helicopter. There were various things that could be done to compensate for the antenna's poor tuning, but that would be a job for the future.
After all, I didn't even own an HF radio yet. (The "HF Chronicles" will continue.)
Editor's
note: ARRL
member Gary Hoffman, KB0H, lives in Florissant, Missouri. He's been a ham since
1995. Hoffman says his column's name--"The Amateur Amateur"--suggests the
explorations of a rank amateur, not those of an experienced or knowledgeable
ham. His wife, Nancy, is N0NJ. Hoffman has a ham-related Web page. Readers
are invited to contact the author via e-mail, grh@heartbeat.wustl.edu.
| Previous: White House Greets Amateur Radio Operators | Next: Florida Man Convicted in Deliberate Interference Trial |
