- 2025
- Jan
- 9
An Unknown 2-dial TRF radio part 2: Identifying things inside.
Back in November, I made a post about a homebrew coffin TRF radio that I picked up for a song at the Scott Antique Market in Columbus. I’ve been digging into this unit some and have identified it as a single RF amp stage TRF.
This helps solve the location of the tubes, from left to right:
UX201A RF Amp
UX200A Gaseous Detector
UX201A Audio Amp
UX201A Audio Amp
I’ll need 90V for the plates of the UX201A, and 22.5 for the plate of the UX200A detector - these apparently can’t be run much past 30V, otherwise they act like a neon lamp and ionize. I’ll also need something for the filaments - the UX2xx all run on 5V, but all the original operator would have had was a 6V dry cell and a rheostat. 5V is really easy for us to get these days, so I’ll probably just yank a linear supply from something and set that up. The other two supplies may require some doing, but I can do this easily enough with linear regulators as well, just lift them above ground.
So…next step is to actually sit down and identify the battery wires based on where they go, which should be easy enough now that I know what they should be connected to!
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … wn-2-dial-trf-radio/