I happen to have a NOS Triad A-104X vertical deflection output autofomer. It is fairly large in size and has three leads, marked ratio 18:1, with a measured resistance of about 1.5k between the blue and red leads, about 5 ohms between red and green.
I have no use for it as its intended purpose, but I wondered if it might serve as a choke in a tube power supply. Or if it had any other audio use other than its original purpose.
I have no use for it as its intended purpose, but I wondered if it might serve as a choke in a tube power supply. Or if it had any other audio use other than its original purpose.
sure you can....you can even load the secondary with a film cap for experimentation...
that traffo is gapped and can even be used as output for say a tube set headphone amp if you have a pair of those....
that traffo is gapped and can even be used as output for say a tube set headphone amp if you have a pair of those....
Some vertical outputs that have separate primaries and secondaries can be used as headphone OPTs. However the auto-transformer type like yours basically can't. You may be able to use it as a choke, although I have no experience doing that. Since it's from a single ended circuit it probably has a gapped core. You would have to determine how much current it could handle by examining the wire size and making an educated guess. Inductance, who knows unless you have a bridge. So it's a try it and see thing.
Edit: An auto-former will have DC on the output tap which you don't want. Unless parafed which complicates things.
Edit: An auto-former will have DC on the output tap which you don't want. Unless parafed which complicates things.
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Thanks! It appears to be fairly large in physical size and weight, and the wires also look pretty thick. I've got a bunch of Stancor vertical output transformers that came in a box of assorted transformers that I got cheap, and this Triad is quite large compared to them. I understand it's a crap-shoot as to the inductance, but I was curious as to whether or not it was even a safe idea to put it into a power section and see what it might do (other than catch fire or explode, you know). 😉
i would think so....at 40mA, voltage loss is just about 6 volts...
the thing is the gap, i would suspect that when used in TV sets, the plate current of the vertical output tube could have been near that also, so i think you will just be fine...
I figured out back in the 60's that the vertical output section of a TV set IS a class A single ended audio amp. It is optimized for operation at a single frequency (60 Hz in the US). I made guitar amps from TV sets in the 60's by liberating the entire vertical sweep section including the OPT. It will drive a speaker directly quite well.
The early vintage Bottlehead SEX audio amp exploited this fact and used a 6DN7 driving a vertical output transformer for a stereo SET amplifier.
The transformer you have is a 3 wire autotransformer which limits its use for audio output since you don't want B+ on the speaker leads. It could be used for a cathode follower output stage, a parafeed OPT or plate choke, or as a choke in a small power supply.
Since it was used in the plate circuit of an SE amp, it is gapped and the optimum current is probably in the 30 to 50 mA range depending on what tube it was intended for. The triodes (6DN7, 6EA7, 6EM7...) typically ran around 30 mA while the big pentodes (6LU8, 6LR8) ran 50 to 60 mA.
The early vintage Bottlehead SEX audio amp exploited this fact and used a 6DN7 driving a vertical output transformer for a stereo SET amplifier.
The transformer you have is a 3 wire autotransformer which limits its use for audio output since you don't want B+ on the speaker leads. It could be used for a cathode follower output stage, a parafeed OPT or plate choke, or as a choke in a small power supply.
Since it was used in the plate circuit of an SE amp, it is gapped and the optimum current is probably in the 30 to 50 mA range depending on what tube it was intended for. The triodes (6DN7, 6EA7, 6EM7...) typically ran around 30 mA while the big pentodes (6LU8, 6LR8) ran 50 to 60 mA.
Fantastic history and information, thank you!
Quick question - something I saw but do not understand. I see in my RC-14 manual a reference to output coupling devices. There are two listed. The first, a standard output transformer. This, I understand. The second, however, is called a 'choke-coil' output, and shows a choke carrying B+ to the plate, and then a direct connection from the cathode to one speaker terminal, and from the plate to the other speaker terminal with a capacitor in between. Is this what they call an OTL design?
no OTL.....
since tubelab has said yours was an auto type, then the transformer option is out, the other two are possible....
since tubelab has said yours was an auto type, then the transformer option is out, the other two are possible....
I spent almost two days in Subic Bay Naval base that I think was right next to Olongapo on my way to Vietnam in 1965. Not such a wonderful place.
I was at Subic a bit later - I joined the Marines in 79. I'm sorry your time was less wonderful than mine - thanks for your service!
can't blame you.....the lease was supposed to end in 1991, but mount Pinatubo erupted and that was the end of the Subic mlitary base....
we used to get high grade irons and JAN tubes from the bases, surplus trade was brisk during those times...
Hi. Old thread but hope someone reads this.
I just discovered a garage full of these.
I can ship globally. Mostly Stancor, but also other makes.
Ping me svanschalkwyk@gmail.com
I just discovered a garage full of these.
I can ship globally. Mostly Stancor, but also other makes.
Ping me svanschalkwyk@gmail.com
Some people pinged me about these. I finally returned to constructing amps and will list these here. I'll ship overseas as nearly all inquiries came from EU.