Midwest 620951 Vintage Power Transformer Tested 310-0-310 / 6.3 / 5 / 12.6 V HUGE 9 lb Tube Amp Project 1953

Fully 60 Hz AC tested and guaranteed vintage tube preamp transformer. AC testing using an oscilloscope allows us to find and reject transformers with noisy outputs, which a simple resistance or continuity test will not reveal. Made in USA in 1953 by Midwest. IEA date code 549323. Weighs 9 lbs 1 oz. Bolt spacings 95 mm by 77 mm. Quantity sometimes available - please enquire.

Here are the verified connections for this transformer:

Input: 117V

Outputs:
620 VAC center tapped
6.3 VAC
5 VAC
12.6 VAC

HV is on pins 4 and 6 of 5U4 socket, CT is wrapped with a pink twist tie. Unlabeled single wire is common to filament pins 2 and 8, and is CT of 5V.

We use a standardized wire identification scheme featuring bright cable ties. In case of any ambiguity, 117V input will be wrapped with a black cable tie, red is high-voltage, yellow is 5V for rectifier, green is 6.3V, blue is 12.6V, white is 117V out for use as an isolation transformer or tubes with series heaters, purple is a second (or third!) 6.3V output. The voltages run a bit higher when run at modern AC levels instead of the 117 VAC that was specified in the 1950s and 1960s. Serial number T-1059.