Hi, KA1RRW
I was looking at the passband filter DCI 145-2H with center frequency of 145 MHz but it has a flat responce 4 MHz large from 143 to 147 MHz (see the skirts diagram) so that it canno't attenuate the very strong POCSAG signal that HB9BNK has at 147.300 MHz In addition I have not seen any notch added in all models for 2 meters band. Do you know if DCI can add a notch to a selected frequency upon customer request ? For example 145.900 MHz center pass-band frequency and a notch at 147.300 MHz ? It would be a very good soluction for Werner HB9BNK
73" de
i8CVS Domenico
----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: "HB9BNK''Werner Kullmann" hb9bnk@uska.ch; amsat-bb@amsat.org; "Dee" morsesat@optonline.net Sent: Monday, May 09, 2011 8:12 PM Subject: [amsat-bb] Re: searching advice on low hpass filter for 146 MHz
http://www.dci.ca/?Section=Products&SubSection=Amateur
You can buy a custom low pass filter for 2-meters from DCI.
Marex had DCI custom build a 2-meter filter for simular usage on Mir. The filter passed 144.000 - 146.000, and had a notch added for 143.xxx. The filter worked great. It reduced most noise out side of the band and it blocked out a 50 watt transmitter located about 10 meters away.
--- On Wed, 4/27/11, Dee morsesat@optonline.net wrote:
From: Dee morsesat@optonline.net Subject: [amsat-bb] Re: searching advice on low hpass filter for 146 MHz To: "'Werner Kullmann, HB9BNK'" hb9bnk@uska.ch, amsat-bb@amsat.org Date: Wednesday, April 27, 2011, 10:25 AM Werner, Since you are using a very good rig and adding a great preamp, to hear what you are after and expense involved might be as simple as adjusting the gain (SP2000 indicates it is adjustable and already has a helical front end) so as to stop this interference. Doing this simple thing might correct everything--Let us know if it works. I adjusted the gain of my preamp to stop similar type intermod. 73, Dee, NB2F
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Werner Kullmann, HB9BNK Sent: Wednesday, April 27, 2011 9:42 AM To: amsat-bb@amsat.org 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 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 _______________________________________________ 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
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
_______________________________________________ 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