[R-390] Alignment help.

Thu, 7 Mar 2002 17:11:34 -0500

Jim,

An AGC problem was my first thought as well.  With a strong signal output
from your signal generator, how many volts do you get on the AGC terminal
(back panel) to ground?  I'd expect about 9 volts or more (voltage will be
negative).

An easy way to check the 2uF AGC capacitor is to first inject a constant
signal with AGC on fast, and note the carrier level.  Move the AGC switch to
med and slow, and note any change in the carrier level.  If the carrier
level indication drops in the slow position, your 2uF cap is leaking a bit.
You'd probably also notice this as a change in the AGC voltage as measured
at the back panel.

Walter Wilson - KK4DF
http://www.knology.net/~wewilson
(REAL Radios: R-390A(x5), R-390(x2), Viking II, Ranger, Thunderbolt, KWM-2A)

----- Original Message -----
From: "Jordan Arndt" <[email protected]>
To: "Scott, Barry (Clyde B)" <[email protected]>
Cc: <[email protected]>
Sent: Thursday, March 07, 2002 4:37 PM
Subject: Re: [R-390] Alignment help.

> The method I use to set the IF gain is by listening to white noise, and
using the line level meter with the line terminated with a 610 ohm
resistor... all I do is adjust the IF gain control to a point just before
the carrier level meter 'takes off '...try it and you'll see what I mean...
> Motorboating sounds more like a capacitor problem than anything else, and
it could perhaps be due to the failure or leakage of the 2uF cap on the IF
deck.. does this occur on all settings of the AGC switch..? 73 de Jordan...
>
> "Scott, Barry (Clyde B)" wrote:
>
> > 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
> > >
> > >
> > >
> > > _______________________________________________
> > > R-390 mailing list
> > > [email protected]
> > > http://mailman.qth.net/mailman/listinfo/r-390
> > > _______________________________________________
> > > R-390 mailing list
> > > [email protected]
> > > http://mailman.qth.net/mailman/listinfo/r-390
> > >
> >
> > _______________________________________________
> > R-390 mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/r-390
> > _______________________________________________
> > R-390 mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/r-390
>
> _______________________________________________
> R-390 mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/r-390
>