need help identifying device

Mike WE0H we0h at YAHOO.COM
Mon Sep 29 20:22:02 EDT 2008

Don't take a deep breath around that baby. Yikes!!!


Chuck McGregor wrote:
> Sorry to add to your bad news, but that white panel behind the power 
> tubes of your diathermy machine sure looks like ASBESTOS.
> --Chuck N7RHU

> WSHU Engineering2 wrote:
>> 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:
>> 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  should you want to 
>> offer something for it and save him the trouble of listing it.
>> Paul A. Litwinovich
>> Director of Engineering
>> FCC License  PG-GB 039245
>> N1MUC

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