need help identifying device
WSHU Engineering2
paull at WSHU.ORG
Mon Sep 29 11:51:49 EDT 2008
My assistant Tony just picked this Frankenstein device up at a live
auction. Pictures are on the link below.
It has two mercury vapor rectifiers (one broken) and two large triodes The
triodes are type 3581, they look like 810s minus the side mounted grid pin,
the grid connection is on the bottom pins. It contains a plate transformer
but no filter cap, so the RF product would be modulated by the 120 hertz
ripple.
It looks like a variable push pull oscillator.The plate circuit is tuned by
a cap with a knob on the front panel. I have not grid dipped it, but it
looks like it is probably in the 20-30 mhz range.
Here is where it gets weird. The tuning cap is labeled Aux volume control,
and a grid series resistor is labeled Main Volume Control. I took one of the
3581s out for the picture. What looks like metering jacks seem to be the
input/ output connectors but the grid coils on each side of the plate tank
sure look like oscillator ticklers to me. Could be neutralization I suppose
if it is some sort of amplifier. Coupling of the plate circuit to the output
jacks is via fixed air capacitors.
It has fillament and Plate switches on the front panel and a 500 mA scale
meter for plate current.
120 volt input. Single transformer supplies fillament and B+ voltages
Pics at:
http://wshu.org/oldradio/device.php
Tony will probably put it up on e-bay if we can figure out what it is, but
you can contact him at tpage at wshu.org should you want to offer something
for it and save him the trouble of listing it.
Paul A. Litwinovich
Director of Engineering
WSHU AM & FM, WSUF-FM
FCC License PG-GB 039245
N1MUC
"RF IS GOOD FOR YOU"
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