[ICOM] 765 freq problem

[jkolin]

Marc....

Just rotate the trimmers back & forth about 20 times. 

Of course mark the orig positions first.

 Radio shud the be stable another 4-5 yrs. Worked for me.


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NE2Q

<div>-------- Original message --------</div><div>From: Marc & Tricia Niebergall <mtniebs at gmail.com> </div><div>Date:02/28/2015  10:45 AM  (GMT-05:00) </div><div>To: ICOM Reflector <icom at mailman.qth.net> </div><div>Subject: Re: [ICOM] 765 freq problem </div><div>
</div>I have begun the troubleshooting and started with the infamous PLL trimmer
capacitors.  I measured the voltages on the four trimmers according to the
service manual and each trimmer was high by about 0.3 or 0.4 vdc.  I
re-trimmed to exactly 6.5vdc on the precise freqs and checked about 1/2
hour later.  The voltages had drifted about 0.3 volts high.  My question:
Is this normal or is this an indication that the plastic trimmers are in
fact in need of replacement?  I would think the voltages should stay
constant at the freqs listed once re-adjusted.

Marc

On Thu, Feb 26, 2015 at 12:43 PM, Marc & Tricia Niebergall <
mtniebs at gmail.com> wrote:

> Tnx to all the contributors for the wealth of knowledge. My suspicions are
> that the solution lies therein.
>
> I'll post my results for others to benefit as I have.
>
> Marc-k7wxk
> On Feb 26, 2015 9:28 AM, "D. Jones" <djoneses at verizon.net> wrote:
>
>> Mouser has the Sprague GKG10015 in stock for 60 cents each.  Comparing
>> specs with the GKG10024 it seems these should work although they are 2.3 mm
>> taller. I don't know if that is an issue.  The Mouser part number is:
>> 659-GKG10015.
>>
>> David
>>
>> <div>-------- Original message --------</div><div>From: Marc & Tricia
>> Niebergall <mtniebs at gmail.com> </div><div>Date:02/26/2015  10:52 AM
>> (GMT-05:00) </div><div>To: ICOM Reflector <icom at mailman.qth.net>
>> </div><div>Subject: Re: [ICOM] 765 freq problem </div><div>
>> </div>Rich,
>>
>> Thanks for the additional info. It seems that the part numbers are pretty
>> scarce, so I would welcome any new info regarding availability of ceramic
>> trimmers.
>>
>> Marc
>> On Feb 26, 2015 7:42 AM, "Rich Dailey" <redailey1 at gmail.com> wrote:
>>
>> > I'm the author of that page. I need to mention that I'm not sure of the
>> > availablility of the replacement trimmers that are mentioned in the
>> > article. If someone has a good link to a supplier of substitutes, I'll
>> > update the page to add those links. Been a lot of years.
>> >
>> > Also, I'll throw in that I recall having one on the bench that had a
>> > sililar drift situation. I replaced the trimmers, AND
>> > 10uf bypass caps coming off a 5 volt regulator. They were pulling hard
>> on
>> > that supply voltage. Seems
>> > it was on the board under the power supply, on a long, shared heat sink
>> > with other regulators. Like I said,
>> > it's been many years, my brain is foggy, but that's what I remember.
>> >
>> > Rich, N8UX
>> >
>> > On Thu, Feb 26, 2015 at 4:57 AM, rrocket88 at netzero.net <
>> > rrocket88 at netzero.net> wrote:
>> >
>> > > here is an old descriptive i've had filed away, was going to perform
>> but
>> > > health went south  good luck K4IMZ
>> > >
>> > > http://home.windstream.net/ferncity/icom.htm
>> > >
>> > >
>> > ----
>> > 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
>> >
>> ----
>> 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
>> ----
>> 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
>
>
----
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