[R-390] Alignment help.

[Scott, Barry (Clyde B)]

Are you aligning the IF deck along with the RF deck?  Sounds like the IF gain is too high.

Barry - N4BUQ

Hello to the group,

I have owned a "massacre" R-390A since the end of Dec '01.  Since that time
I have spent many, many hours in cleaning, recapping, and generally solving
one problem that reveals another problem.  The solved problems generally
relate to cleaning out the intrusive dirt and grime from the storage.  Many
problems have been solved by reworking grounds and intermittent contacts, as
well as a few noisy caps and resistors.

I am at the point where only the alignment remains, I think.

What I am experiencing is this:

1.  The equimpent I have is a good freq counter, VTVM, and Heathkit signal
generator.  All work fine, except that as the alignment progresses, the
radio becomes so sensitive at the higher bands, that the signal generator
will not attenuate enough to keep the diode load at approx 7-8 volts.  At
this point I have been reducing the radio RF gain to reduce the voltage
present at the diode load point.  This works fine, except that the higher
bands are ALIGNED WITH THE RADIO RF GAIN REDUCED to about 1:00 position.

Now, after alignment, with the RF GAIN CONTROL UP FULL, the lower bands work
fine and the antenna peak control is fine.  However, the higher bands seem
to overload and oscillate with a screeching or motorboat putting sound.
When detuning the antenna peak control the overload seems to reduce
somewhat, but with rotation of the antenna peak control, there is much
popping and static.

2.  I am getting the impression that the alignment must be performed with
the RF gain control up full, and the signal generator attenuated enough to
present a diode load voltage of about 7 volts or so.  If peaked with the
radio RF gain reduced, my impression is that, after peaking, a normal RF
gain position will introduce overload at the bands that were aligned with
the RF gain reduced.

SO NOW MY QUESTION..........

Does the overload, screeching, and motorboat putt sounds seem to be a true
alignment problem (obtaining an attenuator), or is there a remaining
component problem that is preventing a good alignment???

Thanks for your past advice, and am looking forward to completing the
restoration of this great radio.

Sincerely,

Jim
73, KF4ICZ



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