[R-390] Oscillator pulling (was re: Call for measurements - 100dB carrier reading)

[David Wise]

 I didn't mean to hammer on you, Jim, I got on a roll and it
came out kind of pungent.  As to your pulling problem, I
don't feel like I have much to contribute right now.
Just the basics like watching the oscillator's B+
supply during the trouble.  This is easiest with
an AC-coupled scope or (if you have one) a differential
voltmeter, and a signal generator to get the environment
under control.

I've changed the subject line to reflect the new topic.

73,
Dave Wise

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net] On Behalf Of Jim M.
Sent: Thursday, August 30, 2007 6:00 PM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] re: Call for measurements - 100dB carrier reading

Sorry if I was critical, it is interesting but I would really like a
solution to another more esoteric problem as long as the gray matter is
networked here - that is the "pulling" of the 17 Mhz 1st crystal
oscillator by strong signals with AGC turned on.  As the AGC varies, the
osc. pulls 50-80 Hz causing a chirp or whoop on CW signals.  Turn AGC
off and it doesn't do it.  Noodle that one.  I am out of ideas - doesn't
happen on my other 390a.  Have changed tubes, swapped crystals, nothing.
N4BE


----- Original Message -----
From: "David Wise" <David_Wise at Phoenix.com>
To: <r-390 at mailman.qth.net>
Sent: Thursday, August 30, 2007 6:18 PM
Subject: RE: [R-390] re: Call for measurements - 100dB carrier reading


A 10 ohm 1-turn pot is 10 ohms per turn.
A 100-ohm 10-turn pot is 10 ohms per turn.