[ICOM] 765 receive problem

[W7RY]

Sounds like you have defective VCO capacitors. I bet it does not do it
on all bands?

73
Jim W7RY


-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
On Behalf Of Glen Rosenthal
Sent: Saturday, January 21, 2006 9:29 AM
To: icom at mailman.qth.net
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


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