[ICOM] IC-775 filters (Was Icom 781 vs. 756 Pro 3)

Thu Dec 7 16:53:53 EST 2006

I am afraid not. All filters are individuals. You must figure out by your 
self what filter or filters that "needs" to changed. Also no matter what you 
do you will be able to make make it to sound 100% alike. To do that you need 
to go DSP, like 756PRO, 746PRO or 7800.

Icom has no 2,1kHz SSB filter.

In the 455kHz filter bank the 2,7 kHz can be changed to Inrad 2,4 for best 
selectivity together with the 2,4kHz wide FL-80 in 9MHz. If you have the 
option SSB narrow filter in 455 kHz installed, the 1,8 kHz filter it can be 
replaced with a 2,0 or 1,8kHz Inrad at your choice.

In the 9 MHz IF the Inrad filters is not plug in. They need to be wired in 
with coax. It has pros and cons. The 9 MHz filters are not so sharp as the 
455 kHz filters. Try changing the 455 kHz filter at first and then with the 
fact that it will never be 100% alike in mind, and than take the dession 
upon if it is worth wireing filters.

Also see Adam Farsons homepage. You can find informaton om the diffrent 
filters and also about the FL-80 + Inrad 109 combo. Also tha manual 
belonging to the 775 and a blockdiagram can awnser som questions.

Also I had a defect 250Hz filter for 9 MHz from Icom that was so bad it 
generated 10 dB additional attenuation than a normal filter. SO filters van 
apparently be bad.

de Anders

----- Original Message ----- 
From: <JMILLER1706 at cfl.rr.com>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Thursday, December 07, 2006 10:09 PM
Subject: Re: [ICOM] IC-775 filters (Was Icom 781 vs. 756 Pro 3)

Thanks,
Can anyone recomend which filter in the 775 needs to be replaced?  The
2.1 kHz SSB filter?  Which Inrad model should be used?
Jim N4BE

----- Original Message -----
From: Anders Janis SM4RNA <sm4rna at telia.com>
Date: Thursday, December 7, 2006 1:46 pm
Subject: Re: [ICOM] IC-775 filters (Was  Icom 781 vs. 756 Pro 3)
To: ICOM Reflector <icom at mailman.qth.net>
Cc: = José Luis Lavalle = <jlavalle at afip.gov.ar>

> I think the only correct way to do is to do something with the
> filters. Any
> adjustment or mod or any other type of fideling with the radio
> will match
> only one or two of the eight filters used in SSB/CW.
>
> Solve the problem at it source rather than cover it up.
>
> /Anders
>
>
> ----- Original Message ----- 
> From: <JMILLER1706 at cfl.rr.com>
> To: "ICOM Reflector" <icom at mailman.qth.net>
> Cc: "= José Luis Lavalle =" <jlavalle at afip.gov.ar>
> Sent: Thursday, December 07, 2006 6:50 PM
> Subject: Re: [ICOM] IC-775 filters (Was Icom 781 vs. 756 Pro 3)
>
>
> Yes, the 775 oscillators appear to all be digitally derived from a
> master source.  I am able to compensate for the filter response
> some by
> offsetting the passband tuning slightly when going from LSB to USB.
> Perhaps I could adjust the mechanical detent on the PBT tune knob.
>
> ----- Original Message -----
> From: Anders Janis SM4RNA <sm4rna at telia.com>
> Date: Thursday, December 7, 2006 11:40 am
> Subject: [ICOM] IC-775 filters (Was  Icom 781 vs. 756 Pro 3)
> To: ICOM Reflector <icom at mailman.qth.net>,= José Luis Lavalle =
> <jlavalle at afip.gov.ar>
>
> > No! The IC-775 do not have such an adjustment. Only 60MHz master
> osc.>
> > On older radios as a IC-765, IC-751 it is possible, though.
> >
> > /Anders
> >
> >
> >
> >
> > ----- Original Message ----- 
> > From: "Fern Rivard" <crc at cyberlink.bc.ca>
> > To: "ICOM Reflector" <icom at mailman.qth.net>
> > Sent: Wednesday, December 06, 2006 9:24 PM
> > Subject: Re: RE: [ICOM] Icom 781 vs. 756 Pro 3
> >
> >
> > > Hi Jim:
> > >    Yes, this may be due to a non symmetrical filter but that can
> > easily
> > > be corrected with re-alignment of both carrier oscillators for
> > usb and
> > > lsb. There's probably nothing wrong with your ssb filter but
> > rather that
> > > those two oscillators have to be aligned properly.
> > >    Cheers from Fern  VE7GZ
> > >
> > >
> > >
> > >
> > > ----- Original Message ----- 
> > > From: <JMILLER1706 at cfl.rr.com>
> > > To: "ICOM Reflector" <icom at mailman.qth.net>
> > > Sent: Wednesday, December 06, 2006 12:48 PM
> > > Subject: Re: RE: [ICOM] Icom 781 vs. 756 Pro 3
> > >
> > >
> > >>I have a 775DSP which I am quite happy with except for the slight
> > >> change in voice tonal quality when switching from LSB to USB
> > (in USB
> > >> the audio spectrum seems to shift slightly toward the trebles).
> > I
> > >> have
> > >> heard someone comment here that this is due to non-
> symmertical Icom
> > >> filters, and that an Inrad replacement would help.  I lost that
> > post,>> so which Inrad model is recommended?  Also which Inrad
> > roofing filter
> > >> would be recommended for the 775?
> > >> Jim N4BE
> > >>
> > >> ----- Original Message -----
> > >> From: Adam Farson <farson at shaw.ca>
> > >> Date: Wednesday, December 6, 2006 2:24 pm
> > >> Subject: RE: [ICOM] Icom 781 vs. 756 Pro 3
> > >> To: 'ICOM Reflector' <icom at mailman.qth.net>
> > >>
> > >>> Hi Charles,
> > >>>
> > >>> Have you tried various combinations of CW filter settings on
> > the
> > >>> Pro3?
> > >>>
> > >>> http://www.ab4oj.com/icom/pro_notes.html#cwfil
> > >>>
> > >>> Cheers for now, 73,
> > >>> Adam VA7OJ/AB4OJ
> > >>>
> > >>> << Example: filters - I like the 781 filters (tight CW
> > filters) a
> > >>> littlebetter than the Pro3 only because of the way they sound
> > >>> under crowded band
> > >>> conditions. >>
> > >>>
> > >>> 73,Charles, K4ZRJ
> > >>>
> > >>> >
> > >>>
> > >>>
> > >>>
> > >>> Scanned for viruses by Blue Coat
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> > >>> ----
> > >>> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> > >>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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> > >>>
> > >> ----
> > >> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
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> > >>
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> > > Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> > > Icom Users Net: Sundays, 1700Z, 14.316 MHz
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> > ----
> > Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> > Icom Users Net: Sundays, 1700Z, 14.316 MHz
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> >
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
>
----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/ 