Continuing the discussion from HF Naive: Kit update. (Part 1) - #100 by G5OLD.
Previous discussions:
@MM0FMF The examples work. I modified a Moxon design many times and the answers were encouraging. The antenna works as promised.
When I try to model one of these low antennas that things go awry. I have also been influenced by a EZNEC guru on another forum who dislikes these compromise antennas but also says EZNEC isn’t good with low antennas.
I will just drop EZNEC for this and experiment with wire.
@G5OLD. Thanks for your comments and photos of hiking poles and your antenna lengths. That first antenna is already on my radar but the second sounds more handy. I have enough wire for both and more.
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Fair enough Dave. I looked and at present I have MMANA-GAL only installed which uses Mininec as its engine. Does it give more correct answers than EZENEC? Pass.
I have 2 antennas I use of HF that need a tuner, everything else is resonant (10m delta loop, 1/4wave GP or centre fed dipoles.) One is a commercial 40/30/20m trapped EFHW. The original matching unit seemed to get awfully hot on 40m with just 5W CW so I use a manual AA5TB style parallel tuned high impedance match. Or if I have a radio with an ATU, either 49:1 or 64:1 unun. The designs are on here for assorted ways of winding and ferrites to use. With either fixed unit the KX2 tuner has no problem matching to 50Ohm. The AA5TB cannot match this on 17m unless a link is opened.
The other antenna is a “41ft random” and counter poises. I made it to see if / how it worked. The antenna and its 9:1 unun takes up so little space in the bag that it stays in there as a backup antenna i.e. I always carry it and normally add in other antennas because I have some reason to use something else. With the 9:1 the measured match was: 7.035MHz 3.6:1, 10.118MHz 8.3:1 14.03MHz 3.5:1, 18.085MHz 2.1:1, 21.06MHz 2.5:1, 24.9MHz 4.3:1 & 28.058MHz 3.7:1 Playing with the length may improve those figures but they are all trivial for a KX2 tuner. Without the 9:1 they will be higher but should probably still be in the range of the KX2’s tuner. But why make life harder for it?
The dimensions/setup I use are here along with Heinz’s suggested improved counterpoise / radial lengths.
Initial description: Testing Antennas during an M5 Flare
Suggested improvements: Testing Antennas during an M5 Flare - #11 by HB9BCB
You can stick the measurements into EZENEC and see what you get.
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If you want even shorter there’s the 5.5m radiator and 2x 4.5m counterpoise, that matches 20m and higher frequencies with the KX2 tuner (a transformer is needed for 40m). The Xiegu G90 can match it on 40m and I have made many contacts with it on 40m even if it’s quite compromised.
It’s a nice length to put on a 6m pole and be a vertical - so no guying or pegging etc. of the antenna. Plus if you’re doing the PVC tube in rocks then even faster!
As seen on Fraser’s, @MM0EFI video - and he credits learning it from @GM0GAV Gavin.
and
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