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Re: Converter gain and noise..



Jens,

A valid point.  My 1420 MHz radiotelescope uses a 35 dB gain preamp into a
DEM downconvertor with 37 DB gain.  This drives my FT-847 to S-9 on the 144
MHz IF.  So I use a 30 dB attenuator after the convertor and this reduces
the signal to a reasonable level for the characteristics of the FT-847.  It
does reduce my overall system NF some but not significantly.

Ed
BTW had a fantastic trip to NJ and Michigan.  I will report when I have
read the 866 e-mail that acccumulated.
 
>Hi
>
>Have anyone experimented with attenuators on the much famed DRAKE and other 
>converters?
>
>I ask because here on the BB i regulary see people boast that AO40 was so 
>and so many dB over S9 at their site, but a little later they mention, as 
>if in passing, that their noisefloor is S5!
>
>This to me indicates vastly excessive gain for the given noisefigure?....
>
>Doesn't anyone care about large-signal handling anymore.
>Please dont tell me that we are all turning CB-mode, brains off :-(
>
>When the 2.4Ghz band becomes more crowded by commercial signals we will 
>HAVE TO face this problem, i suspect.
>
>73 de OZ1LRG
>
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> 

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