[ICOM] Older Icoms question

[Ken Winterling]

John,

I never owned a 720 or 720A, I just repaired them and only used them long
enough to verify my repairs with a few QSOs.  Once you get the rig take a
look inside, it might be possible to run AF to the mic connector without
too much trouble.

A quick look at the schematic seems to indicate that there is a fixed audio
level on the main board at P2/J10 pin 8 or at the junction of R127, 1K, and
R128, 10K.  This is the input to the audio amp section, prior to the AF
gain control.  I don't see a signal level indication so I don't know if it
would be high enough for your purposes.  A scope or AC millivolt meter will
give you a clue.

Good luck!


On Tuesday, September 20, 2016, John Geiger <af5cc2 at gmail.com> wrote:

> Hi Ken,
>
> Thanks for the fast answer.  Guess there is no AF out there.  Do you still
> like the 720A?
>
> 73 John AF5CC
>
> On Tue, Sep 20, 2016 at 12:46 PM, Ken Winterling <wa2lbi at gmail.com> wrote:
>
> > John,
> >
> > According to my IC-720A service manual, there isn't any connection to
> pin 8
> > of the mic connector.
> >
> > Ken
> > WA2LBI
> >
> >
> > On Tue, Sep 20, 2016 at 1:33 PM, John Geiger <af5cc2 at gmail.com> wrote:
> >
> > > On the 1990 and later Icom models the AF output is also found on the
> mic
> > > connector, on 8 pin, which is nice for building a simple digital modes
> > > interface.  Is this also true on the older Icoms like the 720/730/740?
> > The
> > > manual never mentions it, but the wiring for the other pins is the
> > same.  I
> > > have an Icom 720A on the way and want to start working on an interface
> > for
> > > it.
> > >
> > > 73 John AF5CC
> > > ----
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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/
> To support QSL/QTH.net: http://www.qsl.net/donate.html
>