Vintage transformers for tube circuits & more!

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emrr
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Vintage transformers for tube circuits & more!

Post by emrr » Thu Jan 22, 2015 11:12 am

OK, time to let some things go so they can be put back into use. Input, interstage, output, repeat coils, and power. Some singles, some pairs. In this issue:

RCA BA-3 program amp input and output transformer set
(2) RCA MI-38482 nine pin plug-in transformers (McMartin MT-4) tube inputs
Kenyon T-26 pair 600:600
Gates console panel with 3 transformers
Presto PPP 6L6/807 tube record lathe power amp output transformer and choke
Thordarson PP 6V6 to 500 ohm output transformer, good for Sta-Level, etc
Tube output transformer for four 6L6
Pair of IOaudio input transformers for Pultec
RCA potted power transformers 70VCT 800mA
ADC HUM-1 video humbuckers


Kenyon T-26 pair 600:600
One NOS/NIB. +24db, hum bucking construction, typical multiple tap coil, see UTC A-20 impedance diagram as example.
$120 plus shipping/insurance on 3 lbs.
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RCA BA-3 program amp input and UTC output transformer set
Indeed. Both test well. The UTC output is NOS, very difficult to find a high level single ended output like this with good low frequency response. The input is in great shape.
Input is 150/600 to grid.
Output is for single ended 6V6 or 6L6 (RCA did both with this) to 600/150/15/7.5/5 at +30dBm with less than 1% THD 30-15K as used in a BA-3. Lots of BA-3’s in use for vintage audio speaker listening, especially with efficient horn systems.
$600 plus shipping/insurance on 9 lbs.
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(2) RCA MI-38482 nine pin plug-in transformers
Accessory transformer for the 1970’s SA-115 transistor general use amplifier, which appears to be a rebadged McMartin unit. A good guess would be these are rebadged McMartin MT-4’s.

https://groupdiy.com/index.php?topic=73 ... #msg935848

pins 1-3 7.5Ω DC = 125-150 pr
pins 1-4 16Ω DC - 600 pri

pins 5-6 139Ω DC = 10K bridging input

pins 8-9 91Ω DC = 10K sec
pins 2-9 349Ω DC = 60K sec

9 pin sockets frequently available NOS on ebay.

$100 plus shipping/insurance
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Gates console transformer panel
All three measure 8R : 0.7DCR roughly, would appear to be 150:speaker Z. Possibly identical, with center piece having shielding to prevent crosstalk. Maybe perfect for Paul’s bass trick, speaker as microphone.
$30 plus shipping/insurance on 3 lbs.
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Presto tube record lathe power amp output transformer and choke
From a model 88-A power amp, using (4) 6L6/807 type power tubes. Has plate cap attachment for use with 807 tubes, can be removed for standard wiring to 6L6’s. Also the transformers on the later 92-A/B models, which spec within 1dB 20-17K. output impedances of 500/250/15/6 ohms at 50W output. Choke is 10H. The last picture shows how it was used on the 92-A amp, with plate cap attachment.
http://www.hifido.co.jp/KW/G0105/E/0-50 ... -51346-00/
http://www.steveespinola.com/lathetroll ... ic_gif.pdf
$200 plus shipping/insurance on some lbs; heavy.
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Tube output transformer for four 6L6
Apparently from a Baldwin organ with several references suggesting 40W power, tests fine for DCR, leads in good condition. Nice hefty chunk of iron for a power amp build. Part #512-14633D. Organs have to pass some low lows, so inductance should be better than average.
$40 plus shipping/insurance on 5 lbs
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Pair of IOaudio input transformers for Pultec
As provided with his MEQ500 mid range Pultec project back in 2008 or so. They didn’t work for me as I was trying to use them with true 600 ohm source impedances, and they are somewhat rolled off on the bottom in that case. Feed them with a 50 ohm source such as many converters provide today, and they are full range on the bottom, with IOaudio measuring a -3dB point of 14Hz in that case.
$20 plus shipping/insurance on 1 lb.
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RCA potted power transformers 70VCT 800mA
Multiple pieces of very nice potted/shielded power transformers for SS projects. Two are US voltage only, seven more that cover international voltage ranges.
$25/ea plus shipping/insurance on 5 lbs.
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ADC HUM-1 video humbuckers
Off the audio path, into video. I have a number of these to sell. New in original shipping boxes. BNC connectors. Pass audio too, an interesting euphonic sound, probably from the low 75Ω loading.

Here's a typical ad for one at $160:
http://www.markertek.com/product/hum-1/ ... cking-coil

$30 + shipping and insurance. Slightly under 4 lbs / 1.8 kg shipping weight per piece.

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Last edited by emrr on Wed Nov 24, 2021 8:36 am, edited 41 times in total.
Doug Williams
ElectroMagnetic Radiation Recorders
Tape Op issue 73

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emrr
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Posts: 818
Joined: Mon Aug 07, 2006 10:21 am
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Post by emrr » Thu Dec 10, 2015 9:09 pm

ADC 214J sold, thanks.
Doug Williams
ElectroMagnetic Radiation Recorders
Tape Op issue 73

User avatar
emrr
buyin' a studio
Posts: 818
Joined: Mon Aug 07, 2006 10:21 am
Location: NC
Contact:

Re: Vintage transformers for tube circuits & more!

Post by emrr » Wed Nov 24, 2021 8:37 am

adjusted for sold and new items
Doug Williams
ElectroMagnetic Radiation Recorders
Tape Op issue 73

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