[amsat-bb] Question on 23cm WiMo Helix
ny4i at ny4i.com
Thu Apr 2 15:14:22 UTC 2020
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).
Tom Schaefer, NY4I
Madeira Beach, FL (Grid: EL87ot)
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