[amsat-bb] AIDC 3733 Stub

[BobsImsai8800@xxxxxxx]

Joe,

The stub is more of a measurement problem than an operational problem.  When 
people have measured the gain or the response, they can see the hole in the 
response in some downconverters at 2400 MHZ.  Some downconverters have the 
hole somewhere else where it doesn't affect the measurement at 2400. They 
think they that it is broke because the gain doesn't read what it says on the 
cover.

As far as NF goes and downconverter performance, the stub has very little 
affect.  As long as you have no great losses from an excessively long feed 
line, the gain actually needs to be reduced at the receiver. I use the 10 or 
20 dB pad in my IC R-8500.  These downconverters are actually made for a 
fairly long run of RG-59 cable.  That is why people are seeing S meter 
readings of S-5 and above in their receiver with just the added converter 
noise.

Remember TSI makes these things with 3 different IF gains that give 17, 30 
and 37 dB of total gain. For weak signal work, the gain should be low, and 
your S meter reading should be low with the converter is turned on.

TNX & 73,

Bob Seydler
K5GNA
k5gna@aol.com
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