General Transformer C-20933 Ampex Vintage Power Transformer Tested 290-0-290 / 6.3 / 12.6 V Tube Amp Project 6X4 1956

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 1956. IEA date code 412620. Weighs 3 lbs 3 oz. Bolt spacings 58 mm by 51 mm. Quantity sometimes available - please enquire.

This transformer originally provided B+ and heater supply for these tubes: 4 12AX7, 2 12AU7, 6X4

Please see the image of the original schematic for a full list of HV and low voltages available!

Here are the verified connections for this transformer:

Input: 117V

Outputs:
580 VAC center tapped
6.3 VAC
Two total 6.3 VAC outputs!
12.6 VAC

Grey is 25.2 VCT

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-031.