[R-390] Fw: Alignment help.more

Wed, 27 Mar 2002 16:17:55 -0600

Hi Roger, I tend to agree with you about the Tube extenders.
Not worth the effort to try and locate or roll your own. Never
had to use one back in those late 1960 days. In fact
I don't think we even had any that I remember at K-14.
But, if a fellow has the rig and wants to do stage gain checks.
What the hey, its his radio and time and money.
Just another hobby like ham radio or anything else for that matter.

Take Care and back into lurk mode.
Al
W5ADF

----- Original Message -----
From: "Roger L Ruszkowski" <[email protected]>
To: <[email protected]>
Sent: Wednesday, March 27, 2002 11:01 AM
Subject: Re: [R-390] Fw: Alignment help.more

>
> Jim,
>
> What are you doing to an R-390/A.
>
> Since I was drafted and school trained as a repairman in  68 with 8 years
> in service doing it daily
> with a year as Instructor and now an owner, I have jus never needed tube
> extenders to fix
> an R390 or R390 /A.
>
> The voltage get measured with the tube out of the socket.
> If you need to do injection, pull the next tube up and with a cap to
> isolate B+ from
> your signal generator, inject into the plate pin of the tube socket.
>
>
> You can stand the receiver up on either end and lay any deck out on the
> bench and
> get under it to work on it live. You can drop the front panel and work it
> live.
> The PTO comes out and can be worked held in hand.
>
> Pull the diode load jumper.
> Inject some audio into (60 cycle hum) into the audio deck and get
> both audio paths sounding the same. (power will not be equal because of
the
> attenuator in the line side)
>
> Put 455 into the IF deck and get it all working.
>
> Do the RF deck mechanical alignment.
> Get the band switch sync correct.
> Get the crystal deck switch sync right.
> Find the bands that work,
> Work the bands that do not.
>
> If you do not have the parts to adapt the mini BNC to the signal Gen,
> put a cap on the wire lead and inject the signal Gen into the last
> test point of the RF deck. (use a whole lot less than 150 UV because it
> will get amplified in the last mixer) The last test point is a grid of the
> the last mixer (6C4).
>
> You will make more progress measuring resistors gone high in value.
> doing visual inspection for bad solder, and replacing suspect caps by the
> number.
>
> Once you get to a tube stage, It works, It does not work. If your trying
to
> decide if one tube stage is OK not OK by measuring signal level in and
out.
> you are really going at it will out regard to what Elmer's have learned
> about these
> receiver working on them several a day years at a time for now nearly 50
> years.
>
> In the mid 70's after 20 years of prime time big time use, I was still
> found that,
> there is no good table that says what the stage gain of any stage should
> be.
> It has big gain. If big gain is not found fix it.
>
> You can read all about calibrated AN/URM - 25 signal generators all week.
> That is no where near a standard. It just says a tube device is adjusted
> close.
> You can read all about calibrated volt meters.
> That is no where near a standard. It just says a tube device is adjusted
> close.
>
> We will talk about signal to noise like it was dead on, Its just what ever
> we
> got on the bench that day.
>
> Once you get to a bad stage. Working from the head phones to the antenna,
> you go in and do some voltage checks, this will find the smoked resistors.
> You then do a very good eyeball. You know where you are looking and why
you
> are looking
> there. You have isolated the problem to a bad stage. It is bad because it
> does not have
> a big gain as expected.
>
> Get the ohm meter out and point to point verify every thing in the
circuit.
> Crud in deck short.
> Cold solder joint.
> Broken wire.
> Over value resistor.
>
> The caps are killing us after 50 years.
> You can not measure then, most have a lower resistor parallel path.
> So by the number you just swap them all out.
> 1 It is a 50 year old R390
> 2 Experience has shown these item to be problems in these receivers
> 3 A practical affordable test is not available to most owners.
> 4 Testing exceeds return on investment.
> 5 It is just been shown time and time again to do the replacement.
>
> I am not saying change every cap on the bench.
>
> You front paneled your receiver down to one two or three tubes.
> (Yes Alice, you can do that to an R390 or R390/A)
> You jammed a signal generator into a plate pin or two.
> You have decided a stage is suspect.
>
> So now your under the deck and hunting in a circuit between
> two plate pin. This one is good. This one is bad.
> That is a fixed number of parts in a fixed space.
>
> List your problems here and get some specific help.
> Quit trying to solve and reinvent it all by your self.
> It is more fun that way. I do agree.
>
> What is your real objective?
> Do you want some tube extenders, or do you want to fix a receiver?
>
> Roger KC6TRU San Diego.
>
>
>
>
>
>
>
>
>
>
>
>
>
>                     "Jim Temple"
>                     <jetemp@insightbb        To:
<[email protected]>
>                     .com>                    cc:
>                     Sent by:                 Subject:     [R-390] Fw:
Alignment help. (update).
>                     r-390-admin@mailm
>                     an.qth.net
>
>
>                     03/26/02 04:12 PM
>
>
>
>
>
>
> 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" <[email protected]>
> To: <[email protected]>
> 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
> >
> >
>
>
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