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

Tue May 10 06:13:59 PDT 2011

It does not hurt to aks.
DCI has been very responsive to our Space Station projects.
I can assume that there are many european stations that could 
use a 2-meter pass band filter designed for just 144.0 - 146.0.

A notch can be added, but that of course will cost extra.

On a side Note:
Once a month or so, ISS crews will turn on the 143.xxx backup transmitter for a few orbits.  The FM 10k Dev, transmitter will send a carrier for all of the ground stations to lock on to and test with.
If you are trying to work the 2-meter station on ISS While the 143.xxx transmitter is active, the ham reciever will be deaf!
You may still have some down link beacon packets from the Digipeater, but it will not be able to hear you.
The DCI filter project for ISS was rejected as not required.
PS  Ham Voice contacts are also affected while 143.xxx is active.

Miles WF1F

--- On Mon, 5/9/11, i8cvs <domenico.i8cvs at tin.it> wrote:

> From: i8cvs <domenico.i8cvs at tin.it>
> Subject: Re: [amsat-bb] Re: searching advice on low hpass filter for 146 MHz
> To: "MM" <ka1rrw at yahoo.com>, "HB9BNK''Werner Kullmann" <hb9bnk at uska.ch>, "Amsat - BBs" <amsat-bb at amsat.org>, "Dee" <morsesat at optonline.net>
> Date: Monday, May 9, 2011, 4:47 PM
> 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 at yahoo.com>
> To: "HB9BNK''Werner Kullmann" <hb9bnk at uska.ch>;
> <amsat-bb at amsat.org>;
> "Dee"
> <morsesat at 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 at optonline.net>
> wrote:
> 
> > From: Dee <morsesat at optonline.net>
> > Subject: [amsat-bb] Re: searching advice on low hpass
> filter for 146 MHz
> > To: "'Werner Kullmann, HB9BNK'" <hb9bnk at uska.ch>,
> amsat-bb at 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 at amsat.org
> > [mailto:amsat-bb-bounces at amsat.org]
> > On
> > Behalf Of Werner Kullmann, HB9BNK
> > Sent: Wednesday, April 27, 2011 9:42 AM
> > To: amsat-bb at 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 at amsat.org.
> > Opinions expressed are those of the author.
> > Not an AMSAT-NA member? Join now to support the
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> >
> >
> > _______________________________________________
> > Sent via AMSAT-BB at amsat.org.
> > Opinions expressed are those of the author.
> > Not an AMSAT-NA member? Join now to support the
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> >
> 
> _______________________________________________
> Sent via AMSAT-BB at amsat.org.
> Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur
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> 
> 