Author Topic: Plate transformer (5KV) available on Friday  (Read 4290 times)

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Offline AA1IP

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Plate transformer (5KV) available on Friday
« on: May 01, 2008, 02:55:05 PM »
Larry, NE1S, suggested that I post the specs of the following transformer; in case anyone is interested, I'll bring it to NEARFest on Friday. I apologize in advance if this posting is out of line.

Manufacturer: unknown; the numbers stamped in the end bell read...


Height: 9.25 inches plus 1 inch for high-voltage bushings
Depth: 10.25 inches across end bells
Width: 7.25 inches

Weight: heavy. Very heavy.

Approximate core-stack dimensions: 5.5 inches deep by 7.25 inches wide by 9 inches high.

Mounting style: above-chassis or on panel. All connections exit the upper side of the end bells
via ceramic feedthrough insulators.

Mechanical condition: good-plus; paint is relatively intact, with some traces of light surface rust.

Electrical outputs: two 110V single-phase separate primary windings jumpered for 220VAC. primaries measure 0.3 ohms DC resistance (each).

Secondary: center-tapped winding 38-0-38 ohms, with subtaps at 14.6-0-14.6 ohms DC resistance. Center tap is not connected to case.

AC voltages: applying 13.7 VAC to the 220-volt primary produces 173-0-173 VAC across the entire secondary and 138-0-138 VAC across the subtaps.

Scaling the voltages yields 2778-0-2778 volts across the entire secondary, and 2216-0-2216 volts across the subtapped secondary.

At the moment, I can't locate a reference that would translate the core dimensions to an approximate VA capability, but I'll guess that this tranny would very comfortably provide a full kilowatt (and probably several kilowatts) to a tube transmitter. I'd recommend driving the primary from a Variac so that one could easily adjust plate voltage.

Make me a reasonable offer under $50, and it's yours!

To find me, look for a tall (6 ft., 4 inches) guy wearing a hat, a name tag and carrying a canvas
tote bag (plus my usual clothing<g>). I do a lot of wandering, so chances are we'll rub shoulders at least once on Friday. Or, e-mail me at and we can arrange to meet.

Thanks, and 73--

Brad  AA1IP