[Icom] IC-746 built-in Antenna Tuner problems

Tue, 17 Sep 2002 22:53:29 -0400

I had a problem with my 746 that was repaired under warranty several years
ago.  The symptom was that tuning could not be accomplished thought the
tuner below 40 meters.  The tuner would continue to "hunt" until it gave up.
Upper bands were okay.  Icom replaced a defective relay. Bypassing the tuner
the rig was okay on the low bands.

These relays should not be expensive; but, they are also rather small.
Maybe 1.0 by 0.5 inch rectangular. If you try to troubleshoot yourself I'd
get a magnifier lamp.  (I've got two! One for upstairs and one for the
bench.) A service manual will also help.

I'm sure the service guys have seen this before so it won't be a mystery to
them.

This experience did leave me a little shy of using the tuner much above 2:1
so I often now use a Tee match external to the rig.

Good luck,  Pat
wa4tuk

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]On
> Behalf Of WB8FEQ at Home
> Sent: Tuesday, September 17, 2002 9:44 AM
> To: [email protected]
> Subject: [Icom] IC-746 built-in Antenna Tuner problems
>
>
> Hi all.
>
> My IC-746 has been working great for over 3 years but over the last couple
> of weeks I noticed that the antenna tuner is not locking in propperly.  At
> first I thought it was on all bands but further investigation I find it is
> primarily on ten meters.  I even connected a good 50 ohm dummy load with
> three different jumpers.  It can never find a good match (thought the on
> screen SWR readings do go through a good SWR and back to
> infinity.  With the
> tuner out of line the dummy load shows a 1.1:1 reading.  The other bands I
> normally opearte on (75, 40, 20 and 6 meters) seems to be funtioning
> correctly with their respective antennas.  I was wondering if anyone has
> encountered this before and if there is any known "normal" that would be
> seen as the cause of this.   Aany other thoughts/suggestions before I give
> up and send it to a service center (which based on the current size of
> components and my less than perfect eyes may happen even if I find a
> defective component) would be appriciated.
>
> Thanks in advance - Al WB8FEQ
>
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