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I found the manufacturer, but their catalogue's don't have this item. Triad-Utrad, a subsidiary of Litton. http://bitsavers.trailing-edge.com/components/triad-utrad/Triad-Utrad_Catalog_1979-80.pdf It's from 1964 and some sort of transformer? More details would be appreciated. I am fascinated by old electronics and am trying to understand the use. It weighs in at 12.7 lbs or 5.76 kg.

enter image description here

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    \$\begingroup\$ It’s a regular transformer. The 6.3 V tap on the secondary hints to it being used for something with electron tubes. \$\endgroup\$
    – winny
    Feb 29 at 19:40
  • \$\begingroup\$ @winny: a rather specialized "ordinary" transformer,I think... \$\endgroup\$ Feb 29 at 21:32
  • \$\begingroup\$ Good to specify the weight. What are the dimensions? L x W x H \$\endgroup\$
    – Roland
    Mar 1 at 18:22
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    \$\begingroup\$ The dashed lines indicate screens between windings, to suppress interference or crosstalk. Might indicate delicate apparatus. Radar? Special radar? Military? \$\endgroup\$
    – Roland
    Mar 1 at 18:28
  • \$\begingroup\$ The transformer measures 5.5 x 4.5 x 3.75 \$\endgroup\$
    – user363949
    Mar 2 at 11:26

4 Answers 4

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It certainly was for powering tube circuitry, given the filament and presumably B+ secondary windings.

Given the input frequency range, it probably was also for powering something with a high likelihood of being in an airplane.

The 50 Hz suggests it was designed for markets inside and outside the US and could have been used at normal line voltages on the ground, but the input frequency range of 1000 Hz would cover 400 Hz used in aviation electronics.

I worked on "reissuing" mag-amp based voltage regulators for nuclear plant diesel backups a few years ago and the form factor and mechanical design of this transformer are very similar to the '60s military and utility designs we were reproducing.

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That is a power transformer for some sort of vacuum tube equipment.

The 6.3 volt secondaries are for most tube filaments - two of the secondaries have high voltage insulation suggesting that some of the tube cathodes are at high negative or positive voltages.

The 5 volt secondaries would be for vacuum tube diode rectifiers.

It is likely a custom product for some specific application.

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  • \$\begingroup\$ Could it be military radios? \$\endgroup\$
    – user363949
    Feb 29 at 20:26
  • \$\begingroup\$ @MikeA: I don't think so. I think that the need for high voltage insulation of tube heaters would be very unusual. Whatever it was for, the transformer would be custom for a specific customer, not a catalog item. \$\endgroup\$ Feb 29 at 20:40
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This looks like it's a transformer for tube gear using directly heated tubes.

There's a high voltage winding, and several low voltage windings for tube filaments.

enter image description here

(pic source) In an indirectly heated tube (right), the heater filament is insulated from the cathode, so several tubes with the same filament voltage can use the same transformer winding.

In a directly heated tube, the cathode is the filament. Thus if you have several tubes whose cathode sits at different DC bias levels, you need one separate transformer winding per filament.

This is probably a custom transformer designed for specific equipment as the label shows the DC bias of the tubes that would be powered by the filament windings.

5V windings are for rectifier tubes... vacuum diodes that rectify the high voltage to make it DC. There are two, which would mean the 450-0-450 was used to make positive and negative high voltages... which is confirmed by the -300V DC bias on one of the filament windings.

The input frequency spec suggests this may have been used in aircraft.

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  • \$\begingroup\$ Military radio? "We can neither confirm nor deny"... it's a possibility, it could also be anything else \$\endgroup\$
    – bobflux
    Feb 29 at 20:46
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    \$\begingroup\$ The input frequency spec is weird. You wouldn't want to have all the mass of a 50 Hz transformer in an aircraft. What application requires such a wide range? \$\endgroup\$
    – John Doty
    Mar 1 at 18:13
  • \$\begingroup\$ Well... that's an interesting question! \$\endgroup\$
    – bobflux
    Mar 1 at 18:27
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This is a transformer from a piece of military gear or avionics. It's designed for a vacuum tube-based circuit.

their catalogues don't have this item

The catalogue would not tell you much beyond what you can read from the datasheet on the side of the transformer.

It is a transformer, it will fit a circuit that can make use of at least some of the voltages. Sometimes a transformer would have windings that were used only is some sub-models of the device they were for, to ease stock management. On the other hand, extra weight would be a concern in aviation gear. So if this was for aviation, all outputs would have been used.

If you're not a collector but want to sell it - it'll only be of use to hobbyists, so selling it for scrap value would be appropriate.

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    \$\begingroup\$ @MikeA "If you want to sell it - it'll only be of use to hobbyists" This would be of interest in amateur radio. \$\endgroup\$
    – Graham Nye
    Mar 1 at 1:50

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