I rarely deal with valve/tube amps and am more familiar with radio
output-matching transformers primary-windings having DC resistance of
windings of hundreds of ohms.
Been in a shed for years and no known history so treading cautiously.
Measuring the DC resistance of each side to centre tap of this Marshall amp,
shows only about 15 ohm each way.
Amp is 100W o/p using 4 EL34 , two paralleled anodes going to each side of
this impedance matcher.
Does 15 ohm look right for each of these primary coils ?
Output resistance of about 2.5 and 4.5 for 4 and 8 ohm settings seems fine.

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Diverse Devices, Southampton, England
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