[ICOM] 765 receive problem

[Glen Rosenthal]

Thank you, Tim.
As previously mentioned, the VCO Trimmers have been replaced, the PBT mod 
done and the receiver is aligned to specification.

I will check out the BFO as you suggest. The symptom does occur in the 
sideband modes, but it is not as noticeable. As you know, intermittents are 
always the most difficult.


>From: "Tim Moes" <tmoes at wat.midco.net>
>Reply-To: ICOM Reflector <icom at mailman.qth.net>
>To: "ICOM Reflector" <icom at mailman.qth.net>
>Subject: Re: [ICOM] 765 receive problem
>Date: Sat, 21 Jan 2006 14:08:25 -0600
>
>Hi Glen,
>
>You might also try to monitor the carrier osc or replace the trimmers. If 
>it only warbles in CW and all bands it would be the C307 (trimmer) in BFO. 
>If you still have the old trimmers in VCO's that should be done also that 
>was mentioned before.
>
>TNX.... Tim Moes  wd0fkc
>
>----- Original Message ----- From: "Glen Rosenthal" <n0nr at hotmail.com>
>To: <icom at mailman.qth.net>
>Sent: Saturday, January 21, 2006 11:28 AM
>Subject: [ICOM] 765 receive problem
>
>
>>There's a problem with the receiver in my 765 that is somewhat perplexing 
>>and it is more noticeable on CW, especially when the CW narrow filter is 
>>selected and moreso when the 250Hz filter is selected during the first 20 
>>minutes or so of warm-up. It is barely noticeable when in one of the 
>>sideband modes.
>>
>>For lack of a better description, it sounds as though the IF shift is 
>>changing by itself in a warbling fashion. When this is occurring, I can 
>>turn the IF Shift knob to duplicate the sound and the effect it has on the 
>>desired signal in the passband. It does not mitigate the problem. It 
>>happens whether or not the PBT mod is engaged or disengaged by way of the 
>>IF Shift button. When this is occurring, the unit will not receive 
>>briefly, then it pops back to normal. After about 20 minutes or so of warm 
>>up, the receiver performs perfectly. When the unit is first turned on 
>>after it's been powered down for the night, it does not happen - only 
>>during the warm up period.
>>
>>The receiver is perfectly aligned to specifications, the trimmer caps have 
>>been replaced, and the PBT mod has been done, but none of these has 
>>prevented the unit from doing this.
>>
>>I hope I've described this accurately enough to get some direction as to 
>>where to look.
>>
>>Thanks for any suggestions.
>>
>>Glen
>>
>>
>>----
>>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/
>>
>>
>
>----
>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/