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Universal Interstage Transformer UIS-1 MADE IN USA

New Universal Interstage Transformer, 20,000 ohm CT primary with 80,000 ohm quad split secondary. The quad split secondary arrangement (each secondary section is 1/2 the turns of the whole primary) means that as many as 4 tubes can be driven, each independently biased (if wired for 1:1 ratio). May be wired for 1:1 or 1:2 primary to secondary ratio.

Maximum recommended primary DC unbalanced current is 10 ma, however, note that as with other transformers of this type, best performance will be had by having no DC unbalance (operating either parallel fed or push-pull) and with as little driving power required by the tubes being driven as possible (if the driven/output tubes are being run Class A1 or AB1, there will be no driving power required except when the tubes are driven into clipping).

Typically this type of transformer is used with a low-gain tube such as 12AU7, 12BH7, 6CG7, 6SN7 or 6J5 to drive output tubes such as 6L6, 6550, 2A3, 45 or 6B4G. The advantage of using this type of transformer in certain applications is that it gives a different type of clipping behavior, the output tube grids can be driven somewhat into the positive range (because of the low DC resistance in the grid circuit), if a low impedance bias supply is used. It works great for a lot of early (pre-war) jukeboxes.

This transformer could also be used as a "bridging" (high-Z instead of 600 ohms) balanced input transformer for a line amplifier, compressor or power amplifier.

Nice hefty unit, dimensions are 2 5/8 inch wide by 2 1/4 inch tall on 3 1/8 inch mounting centers, weight 1 1/2 pounds (approx 700g).

Hookup Instructions

Schematic


uis-1$34.95

Test Data


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