[R-390] Fw: Alignment help. (update).

[Jim Temple]

Hello to the group,

I have finally found some more time to work on my R-390A.  I have received
several good suggestions, but find that I am stalled because I have no tube
socket test adapters (for testing voltages and resistances).  I have
discovered that testing most voltages is impossible without some of these
adapters.

Before I can proceed much farther, I need at least one of the 9pin and 7pin
tube test adapters.

Perhaps someone on the list will assist me in obtaining the adapters needed
to proceed, efficiently, with test measurements.  Someone must have a few
spares that they will sell.  Thanks.

Regards,

Jim
73, KF4ICZ
----- Original Message -----
From: "Jim Temple" <jetemp@insightbb.com>
To: <r-390@mailman.qth.net>
Sent: Thursday, March 07, 2002 3:09 PM
Subject: Alignment help.


> 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
>
>