[Icom] IC-765 tuner problem

Thu, 9 Jan 2003 19:27:04 -0500

Check out the 765 tuner adjustment procedure under Icom 765 at this site:
http://www.mods.dk/

K8AC
Floyd Sense in Angier, NC
----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Thursday, January 09, 2003 4:13 PM
Subject: [Icom] IC-765 tuner problem


> Hello,
>
> I've noticed that my IC-765 seems to have a problem with its tuner.
> I was trying a new antenna and noticed that the tuner seemed to
> stop at an SWR greater than 3:1 (on the 765's meter) with the
> WAIT LED off and the TUNER LED on indicating a satisfactory match!
> I switched to a dummy load and the same thing happened.
> I thought that perhaps one of the motors had jammed so I removed
> the cover and discovered that both capacitor gears were turning
> but C17's gear (on the right when viewed from the front of rig)
> was moving very slowly. So slowly that if I waited 45 seconds
> it would eventually match the dummy load. No motor noise was
> evident, so I had assumed that the tuner really had stopped
> as the LED's indicated. After that I tried switching bands and
> found that both motors turned at about the same speed. I went
> back to my old antenna and found that everything seemed to work
> properly. However, if I switch to the new antenna I can start
> the whole problem sequence over again!
>
> So it seems that the tuner gets into a state where some of it's
> logic thinks it got a match (even though it doesn't) and C17
> turns so slowly that it's imperceptible unless directly viewed.
> That state persists even after a dummy load is connected.
>
> The main external symptoms are the WAIT LED going off when the
> SWR meter still indicates an SWR greater than 3:1. At this
> point the tuner motor noise stops. The SWR then slowly drops
> over a period of about 30 to 45 seconds.
>
> Before I start taking things apart and adjusting things (i.e.
> breaking things) has anyone else encountered this problem or
> does anyone have any suggestions?
>
> Thanks and 73,
>
> Don
>
> ve3hur
> [email protected]
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