To improve the reception of the sats on 145.9xx MHz with my little yagi, I recently acquired a SSB-preamplifier SP-2000. To my dismay, the reception on my IC910H was intermittend heavily distorted.
After a while I found, that a nearby located commercial transmitter (POCSAG) emitting bursts on 147.300 is so strong, that the frontend of the IC910H (or its AGC) practically quites the receiver on 145.900. When the bursts stop, reception resumes. Difficult to qso.
I have experimented with a large cavity filter and found, that the impact of the bursts can be reduced, so that normal satellite work is possible again.
Now I am looking for advice on how to build a steep low pass filter, eliminating everything above 146 MHz, to be mounted before the preamp on the mast. The filter must however be capable to accept the rf power, if I work in V/U mode.
Thank you for any ideas !
Werner, HB9BNK