You Learn Something New Every Day

Today, we operated a special events station from the Monaghan Antique Engine Show here in Ann Arbor. The organizer of the event is an ARROW member, and he has a van outfitted for communications that he drives out to the site. He has a push up mast on which he mounts a G5RV antenna that he operates in an inverted V fashion. He has an antenna tuner, which he uses to get on 75m, mostly.

Since we were going to begin operation around noon, I figured that we probably should get on 40m instead of 75m. We pulled out the antenna tuner, but I couldn’t seem to get the antenna to tune properly on 40m. The best SWR I could achieve was 3:1. This was odd, I thought, as I was able to achieve very low SWR readings on both 75m and 20m.

At this point, I got on the local repeater looking for some guidance. Tom N8AMX, who was familiar with this setup suggested that the G5RV was not really suited to being operated in an inverted V configuration, and not only that, I probably should try to elevate the ends of the dipole legs. That will reduce the capacitance between the elements and ground and possibly make it tunable.

We were able to raise one of the legs about four feet, and–voila!–I could now get the SWR down to 2:1. We tied the other leg to a branch in a nearby tree, raising it to about eight feet off the ground, and I could now get the SWR down to 1.7 or so. At that point, we decided to see if we could raise anyone. I called a couple of CQs, and got an answer from KF3EA. He gave me a nice 5×7 report.

George, KF8ADV, figured out a way to get the first leg up to about ten feet, and now we were able to get the SWR down to 1.5:1 or so. At that point, Jeff W8SGZ took over the controls and began working stations right and left. I don’t know how many contacts he made, but he was still at it when I called on the repeater about an hour later.

So, what did I learn?

  1. The G5RV is probably best used horizontally.
  2. If you can’t get a good match, get the antenna up off the ground.
  3. Teamwork rocks.

Speak Your Mind

*