Ok, so I was at the hamfest last weekend and picked up a nice little box
that I have no idea of what it does. Allow me to describe it.

Name plate says "Nems-clarke", "accessory unit". "type 121" Vitro
electronics", a division of Vitro Corp of america, Silver Spring, Maryland"

on front it has the following controls

1. Jewel indicator with a 6v bulb
2. 5 amp fuse holder
3. 1.2 amp fuse holder
4. 3 position knob "ac, off, 6vdc"
5. volume
6. "cal" (screw driver turned pot)
7. "zero" (screwdriver turned pot)
8. two prong jack marked "recorder"
9, PM speaker (4 inch 8 ohm)
10. very small, blade type, banana plug looking, socket. Marked Input (back
side only has 1 green wire running to "cal" pot.

On the back
1. j101 looks to be a two pin ac plug
2. j102 4 pin jones connector
3. j103 6 pin jones connector.

Inside
1. Two 12au7 tubes, with corrugated tin overwrap and spring loaded tube
shields (looks like they were built to hold the tubes in place, due to
vibration and or jarring)
2. Big transformer in a sealed rectangular box marked "ac-15380" 15 large
tie posts numbered 1-15
3. Mallory 825s 6 volt replacement vibrator (4 pin)
4. two Sprague aluminum electrolytic caps 30, 20mf (350v) and 40,40 mf (25v)
5. two large adjustable resistors. Biq rectangular wirewound with 10 taps on
the underside

Underside
1. two 1 inch florescent painted squares marked federal ITT, +, 1013, 179736
and 1796012. These look like diodes to me. My Dad had a battery charger that
had one of these plates inside. My brother and I cooked the diode it while
lighting steel wool on fire in the garage!!! yep we were idiots!!!
These two parts are not attached to the chassis. I think that they bolt to a
stud, with a spacer, both of which were found laying in the bottom of the
case.
2. All wires are laced with black thread. Very Very nice job!!!!
3. all resistors are mounted on a fiberglass board with solder tie posts at
each end. Very point to point and very robust, again for vibration??????

Bottom
4 dimple feet
2. a large, long knurled knob that extends to a stud at the top of the box.
It looks kind of like a camera tripod mount. I am guessing that this is how
the "accessory unit" attached to the source.

That's about it...

I have no idea what the heck it is.... my wild guess is that its a mobile
and/or fixed amp for some type of device that would produce a tone or signal
that needed to be beat against for reception. There are no tuning controls
or crystals or anything that would say receiver...
It might just remain a mystery, as google does not show any hits on vitro
electronics type 121. It sure is built like a tank... If anyone has any
ideas,,, post em!!!!!!

Bob in phx

On Thu, 9 Dec 2004 20:22:10 -0700, "bobinphx"
wrote:

snip

My guess is a portable chart recorder driver for some similarly
portable instrument. Late 50s also my guess.

On Thu, 9 Dec 2004 20:22:10 -0700, "bobinphx"
wrote:

snip

My guess is a portable chart recorder driver for some similarly
portable instrument. Late 50s also my guess.