Perhaps not too much magic. 40m vertical on 20m would act as half wave,
with a low radiation angle. 80m vertical on 20m would act as full wave,
with a high radiation angle. Because of mismatch the signals would be
relatively weak compared to matched antennas.
I tried to load my 100' tower, with a large beam on top, on 80m. Tuning
was very touchy, typical of a half wave vertical, but DX signals were very
clear, similar to beverages. Lack of directivity was compensated by
rejection of signals coming at higher angles.
Ignacy NO9E
On Mon, Feb 8, 2021 at 6:06 PM Mike Smith VE9AA <ve9aa@nbnet.nb.ca> wrote:
> All.
>
>
>
> A local mentioned to me his Tribander was broken and he’d been using his
> 40m 4-square on 20m…something I had never tried.
>
>
>
> Today I tried feeding 20m RF into my 40m 4-square. The SWR was too high
> to appease my amplifier with much more than 350watts out, the amp would
> kick out. I suspect it would’ve eventually gone up higher as the dump
> resistor (dummy load) outside heated up, so I quit after a few
> transmissions. Might’ve worked fed through an antenna tuner….not sure.
>
>
>
> The strange thing is….on some signals (USA mostly, as I did this late
> afternoon)….the 40m 4-square actually was stronger on 20m receive than the
> proper 20m 4-square.
>
> I am not sure whether to put this down to arrival angles to/fr the
> Ionosphere, beam direction (QTF) or a poorly working 20m 4-square. My 20m
> array never seems to be as loud on 20m as others in the area using
> tribanders. (I’ve done hundreds of comparisons using the RBN post-contest)
> The previous owner told me the same.
>
>
>
> There was quite a noticeable difference on some signals, but exactly equal
> on others.
>
> I heard a Missouri station CQing a good long while and he was a good
> S-unit louder on the 40m 4-square, as he CQ’d away on 14MHz. The MO stn
> was ~2300km/1425mi from here (ie: 1 x F2 hop more or less)
>
>
>
> I tried changing beam directions on the 40m array and couldn’t get a good
> sense of what the pattern was like on 20m….mostly there was no big change
> in signal strength but I didn’t play with it for very long.
>
>
>
> I also tried feeding 20m rf into my 80m 4-square, where the SWR was
> better, but signals were obviously weaker using the 80m unit on 20m. I
> have used my 160m inverted L on various higher bands when antennas were
> broken here. About the same results.
>
>
>
> Anyways…just a data point or two. Strange as it was.
>
>
>
> Mike VE9AA
>
>
>
> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|