[amsat-bb] Question on 23cm WiMo Helix

Bob Hammond propgrinder at gmail.com
Thu Apr 2 16:05:26 UTC 2020

Tom, I use 55 feet of Belden 9913F (flex) coax from my 9700 to the WiMo
23cm helical antenna and have no issues with AO-92 contacts.
The only issue I have is to remember to decrease the power out!


On Thu, Apr 2, 2020 at 8:16 AM Thomas Schaefer via AMSAT-BB <
amsat-bb at amsat.org> wrote:

> Reading the prior posts about the counterbalance, made me think again
> about adding the 23 cm helix antenna to my sat beams before they go up, but
> I wanted to check my thinking on this…
> There appears to be only one L band satellite, AO-92. That is an uplink.
> Given that, I obviously have no need for a preamp. But I also believe that
> I need not worry too much about using anything better than LMR-400. In
> checking the Times Microwave loss calculator, using LMR400 over a 50 foot
> run would lose 2.6 dB. Using LMR-600, would lose 1.7 dB. 7/8” hardline
> would be .8 dB. But given that the Helix has 13 dBd, that is over 100 watts
> at the antenna. Plenty AO-92.
> So while cable loss seems academic, are there any satellites in the works
> accessible from the US with an L band downlink? If not, it appears LMR-400
> is just fine (even with a short loop of LMR-400 UF at the top for the
> rotor).
> Thanks,
> Tom Schaefer, NY4I
> Blog: www.ny4i.com
> Madeira Beach, FL (Grid: EL87ot)
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