[amsat-bb] RE: 435 MHz AO-40 Uplink

[Estes Wayne-W10191 <W10191@xxxxxxxxxxxx>]

Stacey Mills wrote:

I think this is purely AGC effect.  Sunday activity was essentially US/Canada only and was fairly light
(surprisingly). The AGC wasn't being hammered very hard.  This morning there were LOTS of US/Canadian & European stations, some clearly over powered, and the AGC was consistently running 12+ dB suppression. 
Leila was hopping from station to station like a rabbit on amphetamines and several of these folks showed no signs of reducing their power.  Under these conditions, your downlink would clearly be reduced in strength.

Wayne replies:

Yes, there was surprisingly a lot more AO40 activity on Monday than on Sunday.  But I still couldn't get into the transponder after the footprint moved west of continental Europe (shutting out an Italian station who was stronger than the beacon!).  From 1400-1430 UTC I heard several U.S. stations who seemed to have good downlinks signals with their usual U-band uplink power, and I didn't hear LEILA very often.

My uplink had to be at least 10 dB weaker today.  My S-meter didn't even budge when transmitting 50W to 55 feet of new 9913FX to a 436CP30 antenna.  I just replaced the uplink feedline last week because my uplink had become very weak and variable from day to day.  After replacing the feedline I had good signals for the next two passes, which admittedly had much less activity than today's pass.  But now I'm thinking something else might be the problem.  My M-squared 436CP30 antenna is 7 years old.  I wonder if the phasing cables have gone bad or intermittent?

I guess on the next pass I should be prepared to switch to my 7x7 portable uplink antenna to see if it is better than my 436CP30.

Wayne Estes W9AE
Mundelein, IL, USA

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