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@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 _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb