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AO40 U-AGC question



Am I correct to assume that LEILA detects signals BEFORE the AGC?  That is,
does the uplink power necessary to activate LEILA stay the same as the
U-band AGC changes?  It seemed to me that it took the same amount of uplink
power to activate LEILA during Field Day as it does at other times (~25W
into a 436CP30).

It didn't seem "10 dB harder than usual" for me to get into the AO40 U
uplink during Field Day.  I ran my usual uplink power and was able to hear
myself and a lot of other stations all the time with a 2-foot dish, patch
feed, and low noise preamp.  Do we know if there really is a linear
relationship between AGC value and downlink power for a given uplink?  Has
anybody measured downlink signal strength vs. AGC (with a fixed uplink
power) to see if there is really a linear relationship?  That is, if the
telemetry reports that the AGC jumped 10 dB, does the downlink power of the
test signal really drop 10 dB?   (not sure how this could be measured
because the AGC data is not instantaneous)

All I know is that I ran my usual "not quite LEILA bait" uplink power during
Field Day, and it didn't seem 10 dB harder to hear myself or other stations.
If everybody was 10 dB weaker, I would have had a much more difficult time
hearing everybody with my 2-foot dish.

Wayne Estes W9AE
Mundelein, IL, USA


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