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AO-40 U/S uplink power?



Group

My first week on AO-40 has been outstanding. My second QSO (CW) was with
Mauritius Island, 3B8/JA0QBY! The N3IYR 3ft dish and K5GNA converter
combination work better than I hoped. Adjusting the gain down to where my
S-meter reads S-2, the MB is 6 to 7 S-units ( TS790 ) above the noise with
moderate to low squint angles.

My question is about uplink power. My current uplink set-up is an old 20 x 2
el, KLM on 70cm and the barefoot TS790 ( about 40w ). The coax run is about
60 feet of low-loss LMR400. On CW ( which is the mode I work most of the
time ) the downlink signals at apogee are more than enough ( about 2 to 3
S-units above the noise ), but with SSB, it leaves something to be desired.

I was wondering if this is typical performance for an uplink ERP such as
this, or should I take a good look at the condition of my feed-line and
antenna? The coax is about 3 years old and there are additional N-connectors
inline for the 70cm mast-mount pre-amp.

One more question - my uplink antenna has a polarization switch and I've
noticed a mere S-unit or two difference on the AO-40 downlink when I switch
between RH and LH. I always thought there would be 20db attenuation with a
polarity miss-match? Is it possible that my metalic cross-boom is distorting
things that much?

PS: Many thanks to Glen, N3IYR, Bob, K5GNA and Domenico, I8CVS for all the
help.

73, Tony - AA2AE

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