• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Anyone seen one of these?

I just got this odd two channel SE amp for$50 thinking I’ll just use the transformers but I’ve never seen anything like it before. There are no names or model numbers and it came without tubes except a 5R4 rectifier. I can’t figure out the resistor array on top. Looks like DC heaters. Who has a clue?
 
IMG_0942.jpeg
IMG_0941.jpeg
 
transformer or choke part number 1472800.1 comes up in RCA TV service manual
could have been used in many things though.
2746733.4 is EIA number 274 = RCA, 67 = 1967 33rd week so August, .4 or -4 would be shift number

maybe trace circuit, not sure if those are transformers or chokes.
RCA manual shows 1472800.1 as a choke
.54 H, .3 ADC ,16.6 ohms DC resistance
 
Last edited:
transformer looks pretty big, so likely has 2 low voltage high current windings.
6 or 12 volt heaters, then very large 5v for rectifier.
plate voltage maybe enough for single ended 6V6.

likely RCA part number stamped on one of the bells, or inside bell

if does have amplifier section output transformers for many TV / Radio might been
directly mounted on speaker.
might just be power supply board.
 
Last edited:
On further inspection, those are chokes not output transformers. As was suggested, I’m leaning towards an electrostatic amp of some sort. Those power resistors are 20k ohm in series most likely for the output tubes instead of an output transformer. Definitely DC filament supply. The output terminal blocks have HV and signal connections. Same with the headphone outs. I don’t want to tear it apart if it’s something rare and useful for someone.
 
Administrator
Joined 2004
Paid Member
I'd try to trace it out, I think your suspicions that it is an electrostatic headphone amp probably have merit. I would guess built in the early 1980s, and probably by someone with access to a large commercial/lab EE stock room. I used to build stuff like this early in my career, and the parts pulled from the stock room could span several decades.