XPost: rec.radio.amateur.moderated, uk.radio.amateur, free.uk.amateur-radio

Real-World Amateur Radio

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Yagi matching.

Posted: 22 Apr 2022 10:26 AM PDT https://mw1cfnradio.blogspot.com/2022/04/yagi-matching.html


Last night, I set about getting a 3-element, OWL Yagi from Innovantennas (50MHz) up in the air, simply to get it matched-up properly; sadly, this is
not a location for permanent installations (I'm already very fed-up of this
and putting the house for sale next week, after only a few months here).
The antenna was designed for rear-mounting, but I decided to try it horizontally for inland-based operation (vertical is infinitely better at
the coast).
5-ele version of the 50MHz OWL from Innovantennas. Sturdy, just not very practical for /p; the rear mount of the 3, let alone the 5-ele, also places large, impractical leverage stresses on the boom.


The matching didn't work out too well, in either horizontal or vertical orientation. Although the lowest point in the curve was broadly in the
correct place (~50.25MHz), the SWR at that point was about 1.48:1 when horizontally-mounted. Not the end of the world, but we can do better than
that when, at the SSB and FT8 calling frequencies, the SWR was over
1.5:1.My antenna initially exhibited this type of fairly high-SWR matching, showing the element lengths weren't right.



I didn't think the recommended reflector dimension was long enough; it was essentially the same length as the radiator loop. I increased this by about
2cm per side, and immediately, the matching improved to about 1.38:1.
I then tried increasing the length of the director elements by about 1cm
each side. Again, this had the desired result, bringing the matching to
1.18:1 from 50.150 to 50.320 MHz - SSB and digital portions now perfect!
I'm sure I could bring it a bit lower, but it isn't really necessary.
So, good matching for the OWL antenna, with not too much fuss. I can't say
I'm overly-impressed by the antenna in general, though. It was meant to be
an agreed, portable-specific design, but it's not; the whole feed and loop assembly would be quite time-consuming to undo each time, and I don't like having to jam a screwdriver into a hole as the designed way of tightening a through-boom element nut! The quality of the build instructions is also
quite poor, with a very hurried, error-prone feel to it all. Quite disappointed, overall, but it was cheap enough (£89).

I'm currently building a Moxon to replace this antenna for /p use. In
fairness, the Moxon will likely work out about the same price as the Yagi,
all things considered.




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Computers always catch you out in the end!

Posted: 22 Apr 2022 02:37 AM PDT https://mw1cfnradio.blogspot.com/2022/04/computers-always-catch-you-out-in-end.html


Remember when I had a small number of trolling comments a few weeks ago?
None of them made it past approval, and so none were published.

It now seems that GM4DHJ - or possibly a person falsely claiming to be this operator - has very recently entered some details somewhere on Google,
which have propagated back to the comments made earlier.
Unpublished comments, sporting an alleged link back to GM4DHJ (accessed 22/04/2022)




I can't tell if this really is the operator identified, or an impostor. But maybe the real GM4DHJ can shed some light on which is the case? All
attempts to find contact details for him proved fruitless, so no comment
could be sought prior to publication.

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