[amsat-bb] Re: searching advice on low hpass filter for 146 MHz
g.shirville at btinternet.com
Wed Apr 27 07:50:20 PDT 2011
The DCI filters are VERY good but are designed, as standard, to provide a
bandpass between 144-148MHz!
I guess a special version that is either much narrower, or is setup for
142-146MHz, might give maybe 20dB of attenuation ...maybe this plus your
cavity as a suck out notch/rejecter after preamp would be a winning
----- Original Message -----
From: "John Geiger" <aa5jg at fidmail.com>
To: "Werner Kullmann, HB9BNK" <hb9bnk at uska.ch>; <amsat-bb at amsat.org>
Sent: Wednesday, April 27, 2011 3:04 PM
Subject: [amsat-bb] Re: searching advice on low hpass filter for 146 MHz
>I believe DCI makes a 144-146 bandpass filter.
> 73s John AA5JG
> ----- Original Message -----
> From: "Werner Kullmann, HB9BNK" <hb9bnk at uska.ch>
> To: <amsat-bb at amsat.org>
> Sent: Wednesday, April 27, 2011 1:41 PM
> Subject: [amsat-bb] searching advice on low hpass filter for 146 MHz
>> 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
>> 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
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