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

[Darryl Jones]

Hi Mike,

> If your new rig has an Antenna Trim control, then it's not an R-390A,
> but the less common and (IMHO, anyway) more desirable R-390 -- unless
> you have a variant I never heard of. WHat does the nomenclature plate
> say, _exactly_?

R-390A/URR Serial #212 Stewart-Warner Electronics, Order # 20139-PC-60
The Ant Trim is directly abobe the plate.

> Antenna Trim on mine does have unlimited travel, but the Dial Lock
> does _not_: yours should stop after a reasonable number of turns
> clockwise.

I turned it 360 degrees three times and it locked in place, so all seems
well. Thank you :)

> It pushes in on a clutch that disengages the frequency
> indicator from the tuning mechanism, so that one can set the numbers
> to some multiple of 100 KHz, then turn the Zero Adjuster to disengage
> the clutch and set the electronics to that frequency without moving
> the numbers from where they're set.
>
> Dial Lock is just a mechanical clamp that closes on a disc attached to
> the main (Kilocycles) tuning shaft; it's in two parts, plus a shaft
> attached to the Dial Lock knob, and it may be that the moving part of
> the clamp is missing or mispositioned.

It seemed loose in the case, so I tightened it, and now it takes only one
turn from stop to stop.

> > I changed the power cord to 3 wire as per mil spec, and fired it up, but
> > some
> > of the tubes that tested as "good" (upper 60's) seemed to balk and I
don't
> > have any audio at all, and the Carrier Level meter is around the 60 mark
> > with
> > no antenna plugged in at the back.
>
> It is possible -- even probable -- that the power supply filter caps,
> and many other caps in the radio, are leaky and/or out of tolerance.
> The filter caps can be re-formed: bring the rig up _slowly_ on a
> Variac, starting off at something like 50VAC input.

Great, thanks for the tip.

> You know, I hope, that the chassis will be AC-hot (about 55VAC) if the
> rig _isn't_ grounded, and that if it's pugged into a circuit protected
> by a Ground Fault Interrupter, then the GFI will operate every time
> you turn it on.

I always use GFI's with my electronic equipment, it's become an almost
anal obsession after grenading a KW1 I had when I was a kid. It didn't
trip when I turned the rig on, and all of the tubes lit for a minute or two,
but then some stayed bright and others were very dim, even though I
turned the lights off in here, there was barely a glow.

Before I turned it on, I took out al the modules and visually inspected
them for signs of failed/failing components, and to my surprise, all of the
resistors and capacitors appear to have been changed at some point,
but unfortunately the disc capacitors weren't replaced with orangedrops,
which is something I would certainly like to do. At the moment, however,
I have very little testing equipment, so other than a visual inspection and
electrical testing, I'm limited in what I can do.

Thanks for your advice/help,
Darryl