Hammond 1750EP 15W Paper-Wound Deluxe 5E3 Output Transformer

The 1750EP is a paper-wound push-pull output transformer for tube guitar amplifiers, designed as a drop-in replacement for original units in the Fender Deluxe 5E3 and Princeton. The ordering table lists it as similar to Fender part number 50246. It is aimed at technicians and builders who want the tonal character associated with a paper winding in a 15 watt circuit.

The transformer steps an 8,500 ohm centre-tapped primary down to an 8 ohm secondary at a 15 W rating. Typical DC resistance is 181.6 ohms red-brown and 239.2 ohms red-blue on the primary, with 0.549 ohm on the black-green secondary. Measured at 1.0 kHz, 1.0 V open circuit, primary inductance is 36.0 H (240K ohm) and secondary inductance 31 mH (545 ohm); primary leakage inductance is 32.46 mH.

The drawing specifies a frequency response of 70 Hz to 15 kHz (±1.0 dB reference @ 1 kHz, 27 dBu) and distortion within ±1% across the operating frequency range. Materials and design specifications were kept as close as possible to the original part to preserve the stock tone, and the unit was constructed to look similar to the original where possible.

The open-style frame has 9 in minimum primary and secondary leads: brown and blue primary, red centre tap, black common and green 8 ohm. Drawing dimensions include A 3.250 in, D 2.813 in, E 0.826 in and F 2.325 in. It is rated 1500 VRMS dielectric strength and up to 105 degC, is RoHS and REACH compliant, and ships at 1.1 lbs (0.50 kg).