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RE: no luck w/ voice contacts

> On the AO-51 passes I've tried both QRP and the regular FM. I 
> only hear it for maybe 1 min on good passes, over 60 degrees. 
> Usually i don't hear enough to make out one call sign, On one 
> pass i could hear it for maybe 2 mins but i couldn't hear 
> myself at all.

To me, it sounds like something's amiss.  I can get just about a full pass
of AO-51 using a homebrew antenna and a standard 70cm rig.  You should be
able to hear it for at least 10 minutes, unless it's a low pass.  Another
possible explanation is Doppler shift.  Are you tracking the Doppler on 70cm
as the satellite passes overhead?  The signal will start 10 kHz high and
reduce in frequency until it's on frequency at TCA and -10 kHz when the
satellite disappears over the other horizon.

What could be wrong?

First, Doppler:  Make sure you're tracking Doppler.  Start the AO-51 pass at
+ 10 kHz on the downlink and follow the frequency down as it drifts.  For
ISS (70cm uplink), you have to start with the Tx 10 kHz low and work
upwards.  Having full duplex will help here.

And some more reading (an article I wrote some years ago - references UO-14,
but equally valid for AO-51).

If you're tracking Doppler and things are still not good, try looking at the

Antenna?  Only real way to know is to test it against a known good antenna
(Anyone got an Arrow you can borrow?)

Feedline?  What feedline are you running and how much of it?

Connector? (I've lost count of how many dud BNC solder jobs I've done ;) ).

Receiver - Highly unlikely, but try swapping radios, just in case.
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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