[Icom] IC-765 tuner problem

Thu, 09 Jan 2003 13:42:19 -0800

Do you have a copy of the IC-765 service manual? If not, I'll be glad to=20
provide the tuning-unit adjustment procedure via manual type-in - I don't=20
have a scanner.

73 - Larry W=D8NFU
[email protected]

At 04:13 PM 1/9/2003 -0500, you wrote:
>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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