[R-390] Calibration Osc and 2nd Osc questions

[bill.riches at verizon.net]

Sensitivity below 8mhz might be down as it is a triple conversion set below
8 mhz and there are known sensitivity problems below 8 mhz.  Have you
checked actual rf s/n above 8 mhz and below 8 mhz. On the ones that restore
the average is around  .5 uv.

73,

Bill, WA2DVU

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of thoyer
Sent: Friday, December 1, 2017 7:35 PM
To: r-390 at mailman.qth.net
Subject: [R-390] Calibration Osc and 2nd Osc questions

After tinkering on my R-390A for a couple months, I now have it up and
running, but with a few bugs I'm steadily working out. The questions for
today are:

Why does the amplitude level of the calibration signal drop when I go below
8 mHz? Signals received on the AM broadcast band are nice and strong, but
the cal level is very low. I'll be digging into this issue this weekend so
I'm looking for some "been there, done that" advice. I have yet to probe
around the cal circuit, I'll start that tonight.

Also, the voltage called out for the grid on the 2nd oscillator is -10v - I
measure -.6v. Tube checks fine, a\lso swapped another in - no change.
Oscillator output seems reasonable 7 to 10 Vrms on most bands. I have a
couple bands with bad crystals (determined by substituting in a close in
freq crystal and the circuit producing output). The resistances around the
tube measure in spec. Maybe one of the caps is shot. Before I pulled the
chassis out, figured I'd pose the question here. Don't want to be chasing my
tail........

Overall the radio is coming back to life. Fun stuff..........

Tom
W3TA
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