Unknown 390-K-4 390K4 Transformer 10-0-10 V Vintage Power Tested Tube Amp Project 1962

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 or lossy outputs, which a simple resistance or continuity test will not reveal. Our testing also ensures that you have access to the wires and that they are bundled sensibly, eliminating the "discovery phase" (see below!). Made in USA in 1962. IEA date code 1005238. Weighs 1 lbs 11 oz. Bolt spacings 80 mm by mm. Quantity sometimes available - please enquire.

Here are the verified connections for this transformer:

Input: 117V

Outputs:
20 VAC center tapped

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 220V input or tubes with series heaters, purple or grey 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-1182.