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Help Identifying A VERY Old Vacumm Tube? Answered

I recently got a 1920's RCA Radiola 60 Tube Radio , and when I was servicing it I kinda accidently dropped a tube and the vaccumm seal broke and the glass broke. on the side of the tube it says "Philco H 5" it has four pins two bigger two smaller. Here are some pictures of it for reference.


if it is a full rect. tube it might be a T-5AR4-C (or a 5U4, 5Y3, or a 6CA4) ?

Is it a double rect one or the full rect one or single rect?

I think he meant a dual diode tube, and since a rectifier bridge is made up of 4 diodes, that would be a half wave rectifier tube, and if there is another, then the combination would make a full wave rectifier.

In tube circuits, a dual-diode rectifier is all you need for full-wave rectification. The difference is the transformer, which is center-tapped. A second tube (and socket, wiring, etc.) was more expensive in those days, and a larger transformer with twice the coil wiring was cheaper. You'll see transformers like this speced as 400-0-400, or something similar. It's essentially +400 and -400 in respect to the CT (and you can get 800V if you bridge-rectify the ends and ignore the center.) With silicon diodes costing only pennies, the center-tapped power transformer has disappeared from most modern circuits. Illustration is from wikipedia...


Thanks Gmoon, I was unaware of this aspect of the tube (they were disappearing, more or less when I was still young and never fully got to "play" in that area.....I still remember my Dad's first handheld transistor radio, which took 4 D cells and had what appeared to be a metal shielded tube in it :-) It was in a leather case, no less, made by GE, IIRC.

I wish I had kept it and cleaned it up.....the batteries leaked one day and the battery holder became, um, messy.

You and I are contemporaries (from what you've written, I'm ~ one yr. older), so we both witnessed the "tail end" of the tube era. I only became interested much later (through guitar stuff.) But growing up, we had a tube stereo console, tube TVs, etc... I remember those early transistor radios.... $59 for a radio with three transistors... :-\

yeah, I kick myself every time I think about my throwing it away, when I could have just either cleaned it up a bit in the battery compartment or replaced that piece. I actually found a picture of one EXACTLY like the one I had....


Retro cool. I imagine the majority of these are landfill, which is a shame... (BTW, radio nerds are just as fanatical as guitar amp geeks or audiophile wonks...)

This was a favorite radio of mine too (actually it was my Dad's but I got to use it most often), and I remember it soo well.....the back snapped open, the flap raised and the radio split in two like a suitcase, and the batteries went into the right side and bottom ( with the back laying face down) and the tuning capacitor was nearly the size of a lime....*sigh*
Should auld acquaintance be forgot,
and auld lang syne ?....

Maybe...or maybe you'll find another.

And we'll tak a right guid-willie-waught,
for auld lang syne...

I think the schematic is correct (most of the rectifiers you list are newer than 1930):

280 rectifier search on ebay

This image of a radiola 60 shows a similar "bulb" type (old style tube) glass envelop (tube at the top of pic, according to the chassis drawing, NM's link.) Just like the ebay search results. With a bit of imagination, the rectifier tube in the pic looks to have the same structure as the broken tube...and I know that's the internal structure of a dual-diode rectifier (at least the guts look just like a 5U4 I have here...)

Oh yes....sorry, those I listed were the ones I was more familiar with....I remember Nixie and magic eye tubes well *sigh*

I remember Nixie and magic eye tubes well *sigh*

As do I, and we're becoming as rare as the tubes (LOL)...

(when I was a kid, my cousin worked at Wang labs, and I used to play with the nixie calculators he brought to my grandfather's home in Lowell, Ma.)


I don't have a clue, I am too modern for this old stuff...


9 years ago

There's two four pin tubes in NachoM's schematic. The rectifier and a power triode (output.) From the remains, it sure looks like a rectifier tube (dual diode.) So I'd bet it's the "280" rectifier on the chassis diagram... Good luck--it looks in excellent shape!

That's an awesome radio. My grandfather had one like that when he was a kid. He told me about listening to the first broadcast of the "War of the Worlds" on it. Hope you find the right tube!

. Maybe a 1H5G or 1H5GT? 2B-H5? 2FH5? 3FH5? 6EH5?