[ICOM] 765 freq problem

[Marc & Tricia Niebergall]

Carmine,

We will investigate further.  Thanks.

Marc

On Sat, Feb 28, 2015 at 8:23 AM, Carmine Caira <iz8azz at tiscali.it> wrote:

> You should perform the operation after at least an hour the rig was
> powered up,
> a good warm-up is always mandatory.
> I don't know if deviance after an half our could mean bad trimmers in pll
> board, but if
> the frequency shift you have happens only in usb mode it is sure related
> to usb bfo trimmer.
> I had to replace it in my ic-751a  because  of same problem (usb only).
>
> 73 Carmine
>
>
>
> Il 28/02/2015 16:45, Marc & Tricia Niebergall ha scritto:
>
>  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
>>
>
> ----
> 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
>