UTC P-12

[CJ]

Anyone interested in this guy?
I think it's the same as an O-12, UTC Ouncer, used in the 1176.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_1.jpg

 

[Mbira]

Anyone interested in this guy?

Nahhh......

Oh, OK sure!!

Go to it big boy!

Joel

 

[CJ]

One vote is all it takes for me to start hackin round here,
so....

Schematic:

DCR

Pins:
6-7 6.6Ω
7-8 5.7Ω
6-8 12.4Ω

1-2 7.4Ω
2-3 13.0Ω
3-4 13.9Ω
4-5 8.7Ω

1-5 33.4Ω

Inductance-First value is B-K Precision, Second Value is Sencore LC53, third value is Gen-Rad 1650-B:

Pins:
6-7 1.30H----543mH----355mH
7-8 1.34H----546mH----365mH
6-8 4.63H----2.76H-----1.08H

1-2 456mH----179mH----100mH
2-3 1.32H------546mh----350mH
3-4 1.32H-----544mH----400mH
4-5 463mH----180mH----120mH

1-5 7.49H-----6.94H----3.5H

Sweep test, B-H and Mag Current vs Saturation next.

 

[daArry]

there he goes.... :shock:

:thumb: :guinness:

 

[ciminosound]

Yeah CJ the P series are plug in O series.....

 

[CJ]

Cool, Thanks, Mr. G!

Frequency response was pretty flat, only starts lifting pretty good at about
100 kHz.

But at 1 volt input at low frequencies, it really started to suck the life out of the signal generator to the point that I had to continue the sweep test at 100 mv in instead of 1 v.
So if bass saturation is your thing, this is you input x-former!

Very good phase shift specs, none to speak of from 1 hz to 20 kHz.

Self res unterminated sec is 12.3 v at 275 khz.



http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_freq.jpg

Ring test-1 khz sq wave-first image 1 full cycle, second image has ringing magnafied:

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_ring_a.jpg

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_ring_b.jpg

 

[CJ]

OK, back to finish this guy off.

Leakage-sec shorted=1.77mH
pri shorted=4.15mH

Capacitance-pri to sec=125pf

I'll be darn, if you punch in the average leakage inductance, (3mH) and capacitance in a resonant calculator, you get 260 kHz, very close to the resonant peak on the freq. chart.

B-H---fisrt image- mild saturation, second image-pounding it hard-pretty square metal:



http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_bh1.jpg


http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_bh2.jpg

OK, where's my hacksaw!

 

[CJ]

OK, hack time on the P-12.

I started to saw the can in half and the lid popped off. It is made not of metal, but of black phenolic, an old school insulating material. Polycrystilene wax inside. Goody goody, no black tar to deal with:

Time to break out the heat gun and de-wax this thing:

Drip drip, ooozzz ooozzzz...

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_c.jpg

Darn can got so hot that it warped. The x-former is exposed:

Piece of cake getting the x-former out as the brittle phenolic can breaks like a dry twig in a stiff desert wind:

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_e.jpg

Blue spaghetti insulation over the .015 buss wire break out leads:

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_f.jpg

Melting the rest of the wax now that the can has been peeled away.
Weird bobbin with horns, the horns provide a strain relief for the bus wire so the magnet wire does not get stressed to breakage. Could not find that bobbin in the Cosmo Corp catalog:

Please number your leads before you snip them. Otherwise your disection will be a waste:

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/P12_H.jpg

Snipped the leads and removed the x-former. Going to melt off a little more crud.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/P12_i.jpg

Heating the rest of the wax off also makes lam removal a breeze. 18 EE lams. Count em if you don't believe me. Ooops, some short E's missed the pic. I am betting on 80% Ni, since the smaller size core means less room for copper. Maybe not. I will have to do some Al tests to be sure.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_j.jpg

Your typical UTC glass tape wrapper. Heating the tape will insure that you do not rip any leads out as you un wrap the mummy within:

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_k.jpg

Looks like they wanted some space in between turns for leakage purposes. This coil was obviously hand wound with sporadic numbers of turns per layer.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_l.jpg

This lam is turning up all over the place:

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_lams.jpg

Getting down to the pri/sec boundry. Notice the spacing between turns. One turn of glass tape was the insulation between the primary and secondary. No shield used on this x-former. The turns ratio is only about 1:1.58, and this is a low impedance x-former, which might explain the lack of shield. Remember, transistors sit on the sec. side, not a high impedance tube grid.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_m.jpg

Closer look at the bobbin. Lead numbers get transfered from the wrapper to the bobbin once the x-former has been de-lammed. Otherwise, you peel off the lead numbers with the tape wrapper.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_n.jpg

Ready to unwind the primary.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_o.jpg

All done.

http://vacuumbrain.com/The_Lab/TA/UTC/P-12/p12_p.jpg

What's that you say? You want the vitals?

Well,

 

[PRR]

> I'll be darn, if you punch in the average leakage inductance, (3mH) and capacitance in a resonant calculator, you get 260 kHz, very close to the resonant peak on the freq. chart.

See? Sometimes theory DOES work!

Although: the capacitance you want here is -across- the secondary, including load. This is hard to measure directly: leakage inductance gets in the way, and if you go way above resonance some of the capacitance will drop-out because it isn't a single small neat capacitor but a bunch of little ones connected with stray inductance. In this case you lucked out because 120pFd is a likely total cpacitance for a small core plus some wire and a tube-grid or a meter/scope.

Double-check by throwing 1,000pFd and 3,000pFd on there. The resonance will shift downward. If you add enough capacitance, the unknown winding capacitance hardly matters. When you get a couple points, you can extrapolate back and the "error" for zero added capacitance tells you the winding capacitance.

Oh: the primary-secondary capacitance allows you to estimate the leakage from large common-mode inputs that you want to reject. Less is best. 125pFd, with any available shield grounded, and using the correct end of the secondary, indicates that this is not good for high impedance and high CMRR. (Which could be predicted from the bakelite can and lack of internal shielding.)

 

[CJ]

Cool info Paul!

I was figuring that I must have had a little co-incidental melarkey in there.

Will try the extrapolation method next time. It's a little too late for the UTC!

Ok, turns and stuff:

Coil structure-Pri-Sec. No shields, just a layer of glass tape in between the two windings.

Pri wound first, 0.007 inch wire. 472 total turns. Tap at 234 turns.

Sec wound last, 0.005 inch wire, 747 total turns, first tap at 138 t, second at 237t, third at 235 t, fourth at 137t.

Pretty straight forward. A good candidate for DIY'ing as you could eliminate the taps and just wind 472 turns, tape it, then wind 747 turns. The wire size is very user friendly, it uses a very common lam available at Mag Metals. (EE-24-25)You only need 18, so a sample might be in order.

Bobbin: A Cosmo Corp 7016-0 could be sampled. Dosen't have the strain relief horns, but I am sure you could make do without.

Does not need a mu can.
So there ya go. An 1176 input transformer ready for the making. Tell ebay to shove it!

cj

 

[edanderson]

yay! thanks cj.

ed

 

[CJ]

sorry for the deleted pics but we finally have a print, 

note that this transformer will not do 8 dbm at 30 Hz, 3 dbm is more like it,

and for it to play in phase we have a rev wind.

 

[rackmonkey]

Cool. Glad you’re digging all of these back up!