Memorial Day Antenna Testing

Some time ago, I bought a small, lightweight telescopic fishing pole from a Chinese vendor on eBay.  It’s about 19.5 feet tall and collapses down to about 26 inches.  It’s a great size for backpacking or transporting on my bike.  It weighs practically nothing.  In fact, it’s too light for supporting anything but a lightweight vertical wire.  Although I have used it a few times to support various antenna configurations, I never really found one that was a “keeper.”

Since I had some time over the long holiday weekend, I scratched out a quick design for yet another vertical antenna and cobbled it together with parts I had on hand in my junk box.  I designed it to operate as a base-loaded resonant vertical on both 40 and 30 meters.  On 20 meters and higher, it operates as a non-resonant wire; thus, an antenna tuner is required on those bands.  Along with the loading coil, the matching unit contains a 1:1 choke balun to isolate the feedline.    Both the choke balun and tapped loading coil are wound on toroids and mounted in a small, plastic enclosure.  The radiator is a 19-foot piece of #28 wire.  I could have shortened the radiator to make it resonant on 20 meters also, however, I went with the longer radiator for better performance on 40 meters.  I used four 12.5-foot radials that I made from a 25-foot roll of cheap speaker wire.

The antenna I was testing. The white piece between the telescopic pole and the tripod is an adapter I made from PVC pipe.

The antenna I was testing. The white piece between the telescopic pole and the tripod is an adapter I made from PVC pipe.

Normally, I like to use the “build a little, test a little” approach.  Since I don’t have the luxury of space at home for antenna testing, I just took my chances and built the whole thing.  I headed out to a local park yesterday to give it the “smoke test” and see how close I came with my loading coil design.

My operating location on a cloudy and rainy morning

My operating location on a cloudy and rainy morning

It took less than 5 minutes to set it up.  I used an antenna analyzer to take some initial measurements.  On both 20 and 30 meters, the resonant frequencies were low and fell outside the band.  I still have some work to do there.  On 20 meters and up, the KX3’s tuner loaded it up easily.

The antenna matching unit. The red jumper is used to change bands.

The antenna matching unit. The red jumper is used to change bands.

Next, I wanted to put it on the air.  I started on 40 meters and used the KX3’s tuner to tweak the SWR.  I called CQ a few times and eventually got a call from K4ALE in Virginia.  Bevin said I was 559 with QSB.  Despite the poor band conditions, we had a nice chat.

After I signed with Bevin, I set the antenna for 30 meters and kicked in the KX3’s tuner.  I called CQ and was quickly answered by NN4NC in North Carolina.  Jim gave me a 569.  At times, the band would fade to just about nothing.  As I was chatting with Jim, some drizzle started blowing in under the pavilion where I was sitting.  So I signed with Jim and quickly packed up.

I’ll be doing some adjustments to the antenna over the coming weeks.  It looks, though, that this could be a useful portable antenna, once I get the loading coil straightened out.

Since this is a work in progress, I left out the details for now.  After I get the antenna working as intended, I’ll provide a detailed description, schematic and parts list in a future post.

72, Craig WB3GCK

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