[R-390] New owner with (probably dumb) questions

[Bob Camp]

Hi,

Sounds like you got a good deal. If you want to double you money  I suspect
there are several of us on the list that would be glad to take the poor
beast off your hands :)

The R-390A does have an antenna trim. It is located directly above the
nomenclature plate dead in the top middle of the front panel. Continuous
(360 degree) rotation of this control is normal.

Stripped dial locks are not all that unusual on R-390A's. The assembly is
available from multiple sources here on the list for a minor amount of
money.

The carrier meter sitting at an odd position is simply a sign of the zero
adjust pot not being set properly for the way the radio is operating. I
suspect you have some other problems that may have the levels messed up in
the IF. Simply re-zeroing the meter will take care of the meter but not the
other problems. If the carrier meter is working correctly a reading in the
60's would indicate the RF gain is turned way down. This would also cause a
"no audio" problem.

Almost all of the R-390's had silver tube shields on them. The IERC's are a
rare item. You can get a set of them but it will significantly increase your
investment in the radio. I am not convinced that they are worth the money
they are selling for these days. Tubes are still pretty cheap ...

A number of sites on the web have copies of the various R-390 manuals. If
you can try to download all of them. Each of the various versions has it's
strong and weak points. Any of the better ones will guide you through a
series of voltage checks to figure out what's wrong and what's right with
your radio.

About the only weird piece of test gear you really need is a VTVM (vacuum
tube volt meter). The modern equivalents don't seem to work as well for
troubleshooting old tube gear. The good news is that VTVM's are a sub $50
item these days and often a sub $10 item. The internal calibrator will give
you a good enough signal to get things to the point that you can hear stuff
with the radio. If you are going to do a full up alignment of the radio then
you will need a signal generator. Older generators work just fine for the
task and the big HP R-390 sized units sell for next to nothing. If you have
a generator just about any one will do. There is nothing weird (like with
the VTVM) about signal generators.

Here's what I would do:

Take your trusty VTVM and run through the DC voltages and resistances. You
probably will find a couple that are out of wack. Go through the whole radio
quickly to get a picture of what's going on.

With the wacky readings in front of you try to guess what's going on. Do
this before you start tearing in to anything. It's not a good idea to rip
into the IF module if the power supply isn't running right .... A common
issue is the AGC line. It runs through a bunch of modules and is not a good
first thing to track down.

Your first objective should be to get a signal through on one band through
one of the antenna inputs into a set of head phones. It does not matter
which one or how strong. Any signal is better than nothing at all. It is not
uncommon to find that the radio is dead on half the bands or nearly deaf.
The DC trace should get you at least to this point. Even with major
alignment problems you still should be able to hear something somewhere. If
you can't then you probably still have a DC problem. Once at least one band
has something going on you can then start running through the AC and RF
tests.


    Enjoy!

        Bob Camp
        KB8TQ