[R-390] Alignment help.

Thu, 7 Mar 2002 14:39:55 -0600

Not sure, but that setting sounds a bit high for the IF gain pot.  You might want check Chuck Rippel's site for a procedure for setting the IF gain.  I don't have as much experience with this as others on the list, but it does sound like an IF gain problem (which is what I was referring to when I said IF alignment -- I was including setting the gain as part of the procedure).

Barry(III) - N4BUQ

-----Original Message-----
From: Jim Temple [mailto:[email protected]]
Sent: Thursday, March 07, 2002 2:35 PM
To: [email protected]
Subject: Re: [R-390] Alignment help.

Yes, the IF deck aligned like clockwork.......filters, agc, and stagger
tuned.  Very straight forward.  Of course, the signal is injected directly
into the IF deck.

My confusion is whether or not the sensitivity will be affected. so
radically, with the position of the RF gain control during RF alignment.

After the IF deck alignment, I can only approximate the 150uF input to
obtain the baseline 7volts diode load.  Perhaps this is a critical baseline
to set before the RF alignment?  I have been setting the IF gain control
about 1/8 to 1/4 turn clockwise from full.

Would this affect the final sensitivity so radically?

Jim
73, KF4ICZ

----- Original Message -----
From: "Scott, Barry (Clyde B)" <[email protected]>
To: <[email protected]>
Sent: Thursday, March 07, 2002 3:14 PM
Subject: RE: [R-390] Alignment help.

> 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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