[ICOM] Wanted: Narrower (than stock) SSB filter for IC-735

[John Geiger]

According to the manual, the Icom 735 only has 1 optional filter slot, which
is at the 9mhz IF, for either a 500hz or 250hz CW filter.  Now I am guessing
that you could use the INRAD 455khz filters in the Icom 735 at the 3rd IF,
which is 455khz, but this would involve removing the stock filter that is
there.  It would require some surgery, but would probably end up with a
better filter setup overall.

73s John AA5JG

On Mon, Aug 22, 2011 at 10:09 AM, D C *Mac* Macdonald <k2gkk at hotmail.com>wrote:

>
> Inrad shows that all six of those are applicable to the IC-735.
>
>
> Is Inrad in error?
>
> * * * * * * * * * * *
> * 73 - Mac, K2GKK/5 *
> * (Since 30 Nov 53) *
> * Oklahoma City, OK *
> * USAF, Ret (61-81) *
> * * * * * * * * * * *
>
>
>
>
>
> > Date: Sun, 21 Aug 2011 20:01:16 -0700
>  > From: gfiber at comcast.net
> > To: icom at mailman.qth.net
> > Subject: Re: [ICOM] Wanted: Narrower (than stock) SSB filter for IC-735
> >
> > The 455 Khz filters will not work in the IC-735 Though the 455 Khz
> > filters generally have a better overall shape factor. I like to think
> > that's because the crystals are bigger and easier to grind than the 9
> > MHz crystals are.
> >
> > Gary K8IZ
> >
> >
> > On 8/21/2011 6:56 PM, D C *Mac* Macdonald wrote:
> > > Inrad makes two at the 9 MHz I.F. for $115;
> > >
> > > #123 for 2.8 kHz
> > > #320 for 1.8 kHz.
> > >
> > > They make four at the 455 kHz I.F. for $170;
> > >
> > > #124 for 2.8 kHz
> > > #109 for 2.4 kHz
> > > #314 for 2.1 kHz
> > > #322 for 1.8 kHz
> > >
> > > I guess it's tougher to build filters at 455 than 9,000 kHz???
> > >
> > > Are the 455 kHz filters better than those at 9 Mhz? I checked
> > > the data sheets and noted that several of the 9 MHz filters
> > > had noticably more ripple across the tops of their slope curves.
> > >
> > > The 123 appears to have just a bit sharper cutoff than the 124
> > > but the 320 is a miniscule amount wider than the 322.
> > >
> > > I have located a new 109 (2.4 kHz) filter, but the asking price
> > > is $140 which is about half of a bare 735 is current sell price.
> > >
> > > * * * * * * * * * * *
> > > * 73 - Mac, K2GKK/5 *
> > > * (Since 30 Nov 53) *
> > > * Oklahoma City, OK *
> > > * USAF, Ret (61-81) *
> > > * * * * * * * * * * *
> > >
> > >
> > >
> > >> Date: Sun, 21 Aug 2011 18:25:51 -0700
> > >> From: gfiber at comcast.net
> > >> To: icom at mailman.qth.net
> > >> Subject: Re: [ICOM] Wanted: Narrower (than stock) SSB filter for
> IC-735
> > >>
> > >> I want to say the FL-30 was the original SSB filter nut would have to
> > >> find a print and have a look. I suspect one of your choices will be
> > >> Inrad but it will not likely be a drop in, you may have to use some
> > >> RG-174 to connect it up and some double stick tape to mount it.
> > >> Possibly W4RT has a collins mechanical filter that would work too. I
> > >> don't think the Icom FL-223 1.8 KHz filter will work as the impedance
> > >> for the filter is likely wrong for the 735 circuit. And it has plug in
> > >> leads where the IC-735 lead placement likely will not match and the
> > >> original filter is a solder in type.
> > >>
> > >> Gary K8IZ
> > >>
> > >> On 8/21/2011 5:45 PM, D C *Mac* Macdonald wrote:
> > >>> Subject line says most all of it. I'm looking for an
> > >>> improvement for SSB selectivity at a reasonable(?) cost.
> > >>>
> > >>> * * * * * * * * * * *
> > >>> * 73 - Mac, K2GKK/5 *
> > >>> * (Since 30 Nov 53) *
> > >>> * Oklahoma City, OK *
> > >>> * USAF, Ret (61-81) *
> > >>> * * * * * * * * * * *
>
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