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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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