On 7/27/20 10:02 AM, Scott Dorsey wrote:
Bill Gunshannon wrote:

I just picked up a couple of really nice boat anchors at an
auction house that was forced to shut down by recent events.

An AR-88 and an R-96/SR.

Other than obviously needing retubing, I have a couple of
questions.

They do NOT need retubing. Do not just randomly go swapping tubes for no
reason. Tubes are the -least- likely problem with any of these radios.

My experience has shown otherwise. I collect and restore antique
radios as one facet of my hobbies. I have a number of tube testers
(don't trust just one) and the first tube I pulled from the AR-88
was the audio output tube (6K6GT) and the emissions were about 30%
of what they should have been. I don't randomly replace tubes, but
I frequently find many if not all need replacement.


First, the simplest one. Is there any source for the S-meter
for the AR-88. Mine is the model without it and while it isn't
really needed to use the radio it would be nice.

It should just be a standard meter movement... just find a Simpson meter with
the correct size and sensitivity and you should be fine.

My experience with the AR-88 was mostly that nobody wanted one if they could
get an R-390. There was a training room at Ft. Devens with dozens of R-390As
and a couple AR-88s and absolutely nobody wanted to be at an AR-88 position.
It was sure a lot nicer than typical ham gear of the day though.

I have a couple of R390's that I am working on at the moment. Had
to replace a couple tubes, but most are still OK. Biggest problem
is none of the BFOs work. I was a teletype operator in the early
days in the Army and worked in the AN/GRC-26D and really liked the
R390. Used to be able to listen to WABC in NYC from Germany on the
night shift. :-) But I think I am going to like the AR-88 as well.


The second is stranger. I got two manuals for the R-96/SR.
mine is different from both of them. While there is a hole in
the front for the crystal switch, there is no switch, there are
no crystal sockets and most important, there are no numbers on
the face plate where the switch would have been. Has anyone
ever seen one of these? Is it an older model or a newer model
and the crustal option was eliminated? One other question, I
guess. Are parts available for this one, too? The dial bezel
is missing and so is the power connector. Again, neither is
really needed to use the radio but it would make it look nicer.

Are the manuals you have TM 11-878 and TM-878A? As far as I know, those
things were intended for use on small boats and the like where the stability
of a VFO might have been doubtful. But for all I know they may have had a
bunch of variants of them out there.

Yes, that's the manuals I have found so far.


Oh, yeah. Both work. The AR-88 picks up a lot but doesn't
seem to have the power to drive a speaker. manual says it
only had 2.5 Watts of audio, so maybe that's normal but it
works great with my H-227/U headset. The R-96/SR picks up
some stuff, but I think only strong signals and even some
of them on MW don't come in. Defintely needs retubing.

I would be MUCH more worried about all of those paper capacitors and about
the two audio electrolytics in the AR-88. Change out that stuff first.

AR-88 seems fine in that department at the moment. No background
hum on the audio. But, I am familiar with the electrolytic problem.
I have a Philco that belonged to my parents. When I was 9 I replaced
the electrolytics which were dead shorted. 5U4 plates used to glow
cherry red. :-) Before my mother passed she gave me that radio.
Guess what? It needs to have that same electrolytic replaced again.
Exact same symptom.


If you're really gung-ho about swapping tubes, do it one at a time with a
known-good tube set. If you find performnance improves when you swap a single
tube out, then you know there's an issue with that tube.

I'm not into swapping things to find faults if I can avoid it. I have
tube testers, multi-meters and even an oscilloscope. And still know how
to use them.

But it is really
not all that likely that you're going to have tube issues.

As I said, first tube tested - low emissions. Second tube tested was
just fine. Haven't gotten beyond that yet.


Tubes are not plentiful supermarket items any more, do not just go around
tossing perfectly good tubes.

I don't toss them. I even keep ones with low emissions cause I might
have a radio with a tube with even lower emissions. :-)

bill
KB3YV