[amsat-bb] Re: searching advice on low pass filter for 146 MHz

[Jim Sanford]

Werner:
I EMPHATICALLY agree with the advice to turn down the gain.  Improving 
your IMD will provide much more bang for the effort than trying to find 
a filter with a loaded Q of over 100 at 2m.

An easy way (if imperfect) to get it "right" is to maximize the RF gain 
in the Icom radio and then adjust gain down until the preamp-on noise is 
only SLIGHTLY higher than preamp off.  This gets you enough gain to let 
the preamp set system noise figure, although you still have a bit of excess.

Good luck and please share your results!
73,
Jim
wb4gcs at amsat.org


On 4/27/2011 1:15 PM, Werner Kullmann, HB9BNK wrote:
> What an amazing responsetime on this list !
>
> (post the question, go shopping, find valuable advice !)
>
> thank you all very much !
>
> It will be a few days, until I can get at the antenna. I will
> report my findings here
>
> Thanks and
>
> 73 Werner, HB9BNK
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