daydreaming about building an amp called "Double the Fun"
This power transformer with 2 of these 1641 {RK60} full wave rec tubes and the 7193 driver pushing the 815 output tube. I can't think of anything 2 related for the output trannies.
This power transformer with 2 of these 1641 {RK60} full wave rec tubes and the 7193 driver pushing the 815 output tube. I can't think of anything 2 related for the output trannies.
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The UK equivalent of the 7193 was used in an old RF signal generator of the early 50,s for radio use , it was sold via Practical Wireless (UK) back then .
They are ex-WW2 radar tubes .
That transformer is very unique ! the most I could conjure up is one rectifier attached to a mains transformer .
Going by the photo of the heavy transformer this was used by the USAF each tube delivering 250ma !
If I was you I would look after them very collectable .
They are ex-WW2 radar tubes .
That transformer is very unique ! the most I could conjure up is one rectifier attached to a mains transformer .
Going by the photo of the heavy transformer this was used by the USAF each tube delivering 250ma !
If I was you I would look after them very collectable .
Yeah, the tranny with even one rec tube is rare as hens teeth. That's why god invented the machine shop.
7193 is the best sounding 6J5 I came across, and a couple see off all the 6SN7s I tried including round plates.
I remember those big power transformers from my days of TV servicing in the sixties. Some old black & white sets used them. Can't remember the exact brand name now but perhaps Zenith, Dumont or Andria. And the 815 dual pentode was used in the old Ampex 300 multi track recorders as the master bias/erase oscillator.
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See this thread.......
Getting wacky with top caps
I had a similar collection years ago, but someone offered me too much money for my HY615's and 7193's So they are all gone. Don't know what happened to the 815's, but I sold or gave away over 50,000 tubes and a couple tons of transformers when I had to move everything I owned 1200 miles.
I remember finding a two headed power transformer with a pair of 5U4's sticking out of it in a trash dump or scrapyard somewhere back before 1970. My memory says it was from a 50's vintage color TV with a round metal picture tube, but it was 50+ years ago. I think I used it in a "mother of all guitar amps" project that never really worked right. I have never seen one since, and I explored a lot of military scrapyards in the late 60's through early 80's.
Getting wacky with top caps
I had a similar collection years ago, but someone offered me too much money for my HY615's and 7193's So they are all gone. Don't know what happened to the 815's, but I sold or gave away over 50,000 tubes and a couple tons of transformers when I had to move everything I owned 1200 miles.
I remember finding a two headed power transformer with a pair of 5U4's sticking out of it in a trash dump or scrapyard somewhere back before 1970. My memory says it was from a 50's vintage color TV with a round metal picture tube, but it was 50+ years ago. I think I used it in a "mother of all guitar amps" project that never really worked right. I have never seen one since, and I explored a lot of military scrapyards in the late 60's through early 80's.
Actually, the single-tubed transformers are/were quite common in 1930's Philco radios. That company built electronics to a definite price point with a penchant for "cheepnis" that would put today's Lean Six Sigma-types to shame. These transformers were typical of that approach; they saved the cost of having one or more assemblers install, wire, solder and inspect a separate rectifier tube socket. A bonus was the additional savings of maybe one or two feet of wire per set, which sounds petty at face value until you consider the millions of radios built.
There were a multitude of other such "innovations" like bakelite capacitor blocks, smaller chassis, razor-thin cabinet veneers, etc. In fact, it's a minor miracle so many have survived in good enough condition to be restored today.
I'll put in with you on the shop though. There's literally nothing like a well-oiled machine! 😀
Returning to the original topic, I assume you've seen Pete Millet's 815 amp? Excellent and intriguing work, but I've always wondered if it was possible to build something a bit less complicated with that tube - like class AB2 - with acceptably low distortion.
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