15th and 16th June – Antenna Tests

First failure, then success.

Following a disappointing first test of my end-fed 40m wire antenna up at a local high-spot on Saturday 15th. (I could hear all very well, but no one could hear me!) some re-thinking and investigations took place overnight. I found differing lengths specified for the driven and counterpoise elements on the antenna from different internet websites. My feeling was that the antenna was not resonant but the “miracle antenna” auto-transformer ACU was matching it to give a good VSWR to the rig but the antenna was not radiating well as would be the case if the length was wrong.

I measured off wires to the new lengths (19m driven element and 10.5m counterpoise) ready for testing on Sunday 16th.

I laid out the antenna simply over bushes in my back garden – about 1.5m above ground level. Testing first of all using a Rig Expert antenna analyser I had to extend the driven element another 3m before resonance came down to 7.1MHz.

I then attached the FT-817ND to the ACU and antenna and listened around – again receive working fine, but what about transmit? First I called a strong local station – Bill VK2XT and although I was a relatively weak signal, I managed a nice QSO with this great gentleman who has been licensed for over 80 years.  As I now knew I was getting out I was more confident and when I heard Ron VK3AFW/P up on VK3/VW-009 calling CQ SOTA – I thought “give it a try” and sure enough Ron came back and we exchanged 5-4 reports in both directions. Later I was also able to call and work Marshall VK3MRG/P on VK3/VN-027. It’s really amazing what can be worked running just 5W at each end and very simple antennas!

Here are a few photos of the very basic antenna set-up (click on the photos to see the larger format) – the thin red line you can (hopefully) just see in the pictures is the AWG24 wire wrapping wire (usually used to patch connections under printed circuit boards).

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