[R-390] R-390A w/case / OS-8 scope

[Arvid S. Lundy]

I'm new to this wonderful list due to a neighbor calling up three weeks ago
saying he was moving and wanted to give away an R-390A and a Collins 75A-2.
 I took them not knowing anything about the R-390A (it was built by
Motorola on contract 363-PH-54, and is serial no. 697).  Anyhow the R390-A
has a very heavy aluminum case covered with louvers and painted a somewhat
lighter gray than the front panel.  It does not have shock mounts on the
bottom but possibly did originally.  He told me that this particular
receiver came off the aircraft carrier Enterprise.  I did power it up
briefly and got noise but no signals although turning the antenna trimmer
created noise and the noise level went up & down with both the RF and AF
gain controls.  I want to replace some of the capacitors before I put power
on again.  It did come with three spare 3TF7 tubes and one 6BA6W.  Alas it
may be months before I get back to working on it as I have too many other
projects going.  

I am overwhelmed with all the good info available on this list.  I did
download and print out the entire 21st Century R-390A Technical Reference.
What a wonderful document.  

Guido:
I have a small military oscilloscope with a clamp-on cover which does not
seem to have a nameplate but the cover is stamped OS-8C/U.  The controls
are on top, the CRT is on a small angled panel at the front along with
position, focus, and intensity controls.  The vertical section of the front
panel has two fuses and a pilot light.  It operates on 120 VAC with storage
for the cord on the right side.  On the back are direct screw inputs to the
horizontal and vertical deflection as well as outputs from the horizontal
and vertical amplifiers.  The amplifiers appear to be uncalibrated and I
suspect the vertical bandpass is well under 1 MHz but it does go to DC at
the low end on a fixed gain setting.  The seven position coarse sweep
control is calibrated in Hz rather than time and the maximum frequency is
50 KHz.  Is this what you're looking for?  I acquired it sometime prior to
1960 when I was still active as a ham and have hardly used it.  I seem to
recall trying to use it ~5years ago and not getting a beam but I pulled it
off the shelf and plugged it in today and got beam right away.  Alas there
appears to be noise in the amplifiers so I can't get a smooth
trace-actually it looks like there's a smooth trace and it then doubles
back on itself about halfway with noise.  Maybe just problems in the
blanking circuit.  I suspect it needs to have some capacitors replaced at
the very least but the CRT seems OK and the physical appearance is pretty
good.  If you're interested I can photograph it and email the picture.  You
can reply off list.

Arvid
alundy8@earthlink.net