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AO-40 reception question



When AO-40 was first turned on for amateur use, I was able to hear 
others' downlinks
well enough for an SSB QSO (sigs were in the noise, but useable).

Lately, it seems, (using the same equipment: Meyers dish, unmodified 
3733, ft-847),
all the downlinks seemed to be down deeper in the noise and not 
strong enough for a QSO.

I have swapped the 3733 with another one, with similar results. I 
also tried using a different
wall-wart / bias-tee. No difference.

I recently added a DEMI preamp (recently tweaked by DEMI), between 
the Meyers feed and the 3733.
The signals are helped by the preamp, although they are still pretty noisy.

I get S-5 background noise (away from the beacon freq), on the '847, 
and the beacon itself is at S-6.

I know that on some passes, I was looking through a tree, but one 
particular pass
was clear of the tree and still weak (could be a combo of good view / 
bad squint).

I have a couple more things to try. I have the K5GNA filter to 
install, and I need to try cutting the stub.

A friend of mine is also using an unmodified 3733 and finds downlinks 
only strong enough
  for CW QSO's.


Perhaps all this is just tree / squint related, but in general, It 
just seems like conditions
used to be better.






-- 

Bill Howell
University of Texas at Austin
College of Fine Arts
Office of Computing Technologies
N5ALO  Amsat 32459  QRP-L 415
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