Hammond 1650M 60W Push-Pull Output Transformer, 1400/800 Ohm CT

The 1650M is a 60 W push-pull tube output transformer with a dual-impedance primary of 1,400 ohms CT or 800 ohms CT, 318 mA DC per side and 4, 8 and 16 ohm secondaries. The very low primary impedances distinguish it from every other model in the series; the manufacturer data gives no operation mode or suggested tube list for this part, so select it from your own design calculations.

Construction follows the classic series design: the transformer is enclosed (shielded), with 4 slot, above chassis Type "X" mounting, plastic coil forms for coil support and insulation, and insulated flexible leads (8 in minimum per the part drawing). Frequency response is 30 Hz to 30 kHz at full rated power, +/- 1 db max (ref. 1 kHz) minimum. Because of the unique interleaving of the windings, both secondary windings must be engaged to meet specifications.

Dimensions from the series table are A 3.13 in (80 mm), B 4.19 in (106 mm), C 3.80 in (97 mm), D 2.50 in (64 mm) and E 2.94 in (75 mm), with 0.20 x 0.38 in mounting slots. Typical electrical data from the drawing includes a primary inductance of 64H / 30.3KOhm, leakage inductance of 4.56mH, a dielectric strength of 2000Vrms and a temperature range of -40 to 105C. Shipping weight is 8 lbs (3.63 kg).

The 1650M label is marked Made in Canada, and the part is REACH and RoHS compliant. The manufacturer notes that tube operating conditions change the optimum plate-to-plate load, so consult a tube manual or data sheet before choosing an output transformer.