[R-390] No Peak on T701

[Bill Hawkins]

Ah, les'see, the output PTO coil will not peak.

Doesn't seem like it would be a good idea for it to peak.

The PTO generates 2.5 to 3.5 meggycycles, and they've all got
to be mixed with the masticated RF from the RF deck. A sharp
peak at 3.0 MC would seem like a very bad idea. If you want a
reasonably level signal for 3 +/- 0.5 MC, you want a really
low Q circuit.

What have I missed?

Bill Hawkins


-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of Barry
Sent: Saturday, April 29, 2006 10:23 PM
To: R-390A
Subject: [R-390] No Peak on T701


I've been doing some more tweaking on one of my R390As.  T701 (output
transformer from the PTO) will not peak.  I'm getting slightly less then 2V
peak to peak no matter how I adjust the slug.  Anyone ever seen this
behavior?  If so, any ideas what's wrong?

I've done some resistance checking on V701 and nothing is all that far off.
Since the slug tunes the plate tank, I'm wondering if the problem might be
with C706.  It's supposed to be adjustable, but how?  Reading the Y2K
manual, it states C706 is a variable glass dielectric cap.  Not sure what
that is, but with the PTO out of the radio and the cover off of Z702, I see
a clear cylinder in which the slug moves.  Is that C706?

Thanks for any help or advice on this.

Barry - N4BUQ

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