[amsat-bb] Question on 23cm WiMo Helix

Rick Walter wb3csy at gmail.com
Thu Apr 2 15:43:55 UTC 2020

There is no L band satellite downlink available In the US. 

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"Every kid starts out as a natural-born scientist, and then we beat it out of them. A few trickle through the system with their wonder and enthusiasm for science intact" - Carl Sagan

No trees were killed in the sending of this message, however, a large number of electrons were terribly inconvenienced.

> On Apr 2, 2020, at 11:17 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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