identify a transformer

[rudutch]

This was in with a bunch of crap I bought, it appears to be unused
Looks like a 20W (or so) output transformer

Marked
Chicago Transformer Co
H-366C
A9-117

3 wire input (wt / gn rd)
4 wire out (bk / gn / yello with blk stripe X2)

written on top (with a maker) very faded "70 ult juke box"

did my internet search and came up empty

anyone have a bright idea?

[guitician]

You can ohm the windings with an ohmmeter. Primaries are usually in the hundreds of ohms. If you have a signal source, you can measure the turns ratio, and maybe the output impedance. But then, it may not be worth the time for you to bother.

[rudutch]

[stokes]

There is a procedure I can explain to you to determine what tubes/speaker load you can use with that tranny,but you need to be able to put a small ac voltage on it and measure.You will need a variac or preferably a signal generator and a meter.If you have these let me know and I'll explain.I dont think that will handle 20 watts,tho it is hard to tell from that pic.It doesnt look very big.I would guess more like a Champ 5 watt.

[pontiacpete]

hey Stokes

I have both of those, can you explain the procedure?---I'd like to try it.

pete

[stokes]

Put a 1/2 volt 1K signal on the secondary,measure the voltage coming out across the entire primary,lets say you get 20vac,that would make your turns ratio 40:1,now square the 40 and get 1600,multiply the 1600 by your speaker load,lets use 4ohm so your primary impedance is 6400 with a 4ohm speaker.That means this transformer would be good for a pair of 6V6 or EL84 power tubes.The transformer pictured is a multi tap secondary,so I would use the entire secondary winding for the test.Measure the dc resistance of each wire to the black wire to determine which tap is your entire winding.The one that reads the highest resistance is the biggest or entire winding.Ruduch,I misspoke in my first reply,that transformer in the pic is a push-pull so it looks more like about a 10watt push-pull tranny,cant really get a lock on how big it is,so maybe as much as 15 watts.

[rudutch]

Thanks for your complete and helpful response. I don't have a variable ac supply and don't wanna use 110v @ 15a either.

It is the same dimension as my mission 5E3 OT... I have an old (and I mean old) eico 147 that is supposed to test OT, all I did was get frustrated.. I also have an old freq gen that I have not brought in form the pile yet. maybe that will have a output I can use

I was hoping the part numbe would mean something to someone..

thanks again

[stokes]

The freq generator should be able to give you a half volt or so.Is it an audio generator or an R-F generator?The audio generator is what I use,but I think most R-F generators have the ability to supply a simple sine wave like an audio generator.In any case as long as it will give you a stable .5 to 1 vac it will suffice.

[Bruce / Mission Amps]

Thanks for your complete and helpful response. I don't have a variable ac supply and don't wanna use 110v @ 15a either.

It is the same dimension as my mission 5E3 OT... I have an old (and I mean old) eico 147 that is supposed to test OT, all I did was get frustrated.. I also have an old freq gen that I have not brought in form the pile yet. maybe that will have a output I can use

I was hoping the part numbe would mean something to someone..

thanks again

Use two alligator clip leads and the 6.3vac leads from any of your tube amps to shove into the unknown OT instead of 1/2vac.

The math is the same a stokes says but you'll see a ton of VAC on the primary side if you drive the secondary with the 6.3vac so be careful you don't wake up in a puddle of pee.

[Enzo]

I have a different take. I bet it is a 70v speaker matching transformer for use in a CV speaker array. I see the writing more as 70 volt juke box. Juke box amps always have 70v outputs and remote speakers are almost always wired for it, thus neccessitating a small transformer for each speaker.

I would also observe that while the part does say Chicago on it, and there is or was a Chicago Transformer company, this part appears to say Central Transformer as the brand. The company still exists as a part of Central Maloney. if you contact them, they could conceivably have some old information on the H-366C.

[rudutch]

you, sir are correct, Central transformer it is. if it is 70V it would make a boat anchor or a treasure for someone. I has hoping for something useful..

anyone in search of this rare, fine jewel- email me

Enzo 2
Me 0