Re: [amsat-bb] AIDC 3733 Stub

[Joseph Murray <k0vty@xxxxxxxx>]

And if you are using the DC injector , the attenuator needs to be next to
the receiver before the injector in the IF coaxial line.

Joe  K0VTY
=========================
On Sun, 08 Apr 2001 10:24:57 -0400 Douglas Braun NA1DB
<doug@dougbraun.com> writes:
> Remember:  If there is going to be any attenuation in the IF path, it 
> is
> better to put it just before your receiver than in the 
> downconvertor.
> That way it will also attenuate any leak-through of local 2-meter
> signals into the feedline.
> 
> Given this, it makes to disable the stub.
> 
> Doug
> NA1DB
> 
> At 05:52 PM 4/7/01 , BobsImsai8800@aol.com wrote:
> >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.
> 
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> 
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