Here’s a really simple way of double checking how to much to trim your antenna elements.
You only need to type in the numbers in the Cyan boxes.
Just type in where it is resonant right now – then type in where you would like it to be resonant and the spreadsheet will auto-calculate the trimming.
* Thank you to Aubrey (AubsUK on YouTube) for the Online version below:
So I have just taken delivery of a very gently used Tokyo Hy-Power HF linear amplifier.
The previous owner (retired communications and instrumentation technician for a large, multi-national organisation) replaced both fans with ultra low noise “Arctic” fluid bearing units. These are installed in 2 speed via voltage regulation manner: Low speed during stand-by (RX) and High speed during TX. Continue reading
Regulars will know about the DX Commanders very cool results which are now filtering through in real world successful contest scenarios.
My own issue is that I needed just one antenna that would deliver an all-band solution, certainly for the contest bands of 40m, 20m, 15m and 10m – but I also needed 80m in the mix too.
My holiday home has a very compact small garden so the option of putting up a dipole for 80m is out the question, but modelling suggested than exchanging the 30m element for an inverted L for 80m should work.
The 80m element therefore starts vertical, like all DX Commander elements and turns a sharp corner at 6.9m above ground and droops down for around 13m or so, hanging over a bush at around 3m off the ground. Probably not perfect but perfectly adequate to score 44 QSOs inside an hour on the Saturday eve of the IOTA contest. That score includes 16 different IOTA multipliers, certainly a wide spread around Europe.
I’m absolutely delighted to report that I was placed 4th overall in the world for IOTA-Fixed station, Unassisted, Low Power, 12-hour section. This was from a holiday home and I installed the antenna inside 1-hour.
Results here – but what makes this more remarkable is that I only used the one antenna from 80m through 10m; DX Commander All-Band-Vertical.
For 80m, I confirgured the DX Commander as an Inverted-L, replacing the 30m element. Of interest, 30m was still achievable (albeit with a 4:1 SWR). Although 17m is not a contest band, I did notice some slight interaction with the new 80m element, however SWR was still acceptable without an ATU.
I logged 300 QSOs however I notice after adjudication, that fell to 289. Pretty good, only dropping 11 QSOs. And I was amazed at how effective the 40m element produced such startling results on 15m, effectively as a 5/8th. Even 10m as a 2.5m long, ground mounted quarter-wave was getting in the action with short skip too.
All in all, I’m extremely delighted that I test-proved this antenna from a holiday location in competition with my peers, who were using genuine fixed-station antennas.
