[amsat-bb] UO-11 "S" Band Beacon

["Colin Hurst" <hurst_cj@xxxxxxxxxx>]

All,
I noticed my call mentioned in a recent post re : UO-11.
I have been copying UO-11's 2401.5 Mhz beacon on and 
off for some period of time, primarily as a test signal. 
I was initially advised that because it uses the opposite sense 
of polarity to AO-40 it was next to useless. 
However that only presented a greater challenge. 
As I improved my performance capabaility 8 turn experimental 
helix to a 750 mm dish (a quantum leap) I detected FM when 
receiving as an SSB signal. That immediately brought back 
many memories of receiving UO-11 telemetry using a Z80 
assembled program on a Tandy Model 1 clone.
By monitoring a number of overhead passes (much easier on the 
az-el with the dish) I was able to achieve full quieting (short periods)
 in the FM Mode and clearly hear the UO-11 modulation, albeit at 
very low level deviation. Now that I have added a preamplifier, full 
quieting can be managed for significant periods.
Make sure you have the latest set of keps and set your tracking
update. I use a 2 degree change on my Sattrak3. Not a problem
with AO-40 but UO-11 may wear out the rotators at a faster rate.  
BUT you have to pick your pass and I generally find it is better as 
the bird goes away from you. As a reliable signal source for S band 
evaluation, my original advice is correct. It is next to useless. 
However if you are patient, monitor a number of passes, and have 
good rx capability you will be pleasantly surprised. 
For what its worth.
Best regards,
Colin VK5HI

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