1760F Hammond PP Übertrager Fender Blues Junior 049969

Hammond 1760F – Blues Junior output transformer for 049969 / 49969

The Hammond 1760F is a paper-wound, centre-tapped push-pull output transformer for valve guitar amplifiers. It provides a 6.95 kΩ plate-to-plate load, a 15 W rating and secondary outputs for 4, 8 and 16 Ω.

Hammond lists the 1760F for compatible Blues Junior output stages. Its current application page identifies Fender reference 49969, while an older official Hammond selection guide writes the same reference as 049969.

Suitable applications

• Repair of compatible Blues Junior amplifiers
• Applications identified by the documented reference formats 49969 and 049969
• Push-pull output stages using two EL84 valves and a nominal 6.95 kΩ plate-to-plate load
• New builds requiring 4, 8 or 16 Ω speaker outputs
• Replacement of a Hammond 1750F when additional 4 and 16 Ω outputs are required

Technical data

Product type

Push-pull output transformer for valve guitar amplifiers

Manufacturer application

Blues Junior, 15 W

Fender reference

Currently 49969; also written as 049969 in an older official Hammond guide

Primary impedance

6.95 kΩ plate-to-plate, centre-tapped

Secondary impedances

4, 8 and 16 Ω

Transformer power rating

15 W

Winding construction

Paper wound

Frequency response

70 Hz to 15 kHz, 0/-2.5 dB referenced to 1 kHz

Manufacturer distortion figure

Less than 3% at 70 Hz under the test conditions used in the Hammond data sheet

Primary inductance

2.56 H typical at 1 kHz, 1 V with the secondary open

Leakage inductance

3.68 mH typical at 1 kHz, 1 V with the secondary shorted

Primary DC resistance

147.90 Ω between brown and blue, typical

Secondary DC resistance

0.171 Ω black–yellow, 0.245 Ω black–green and 0.476 Ω black–white, typical

Dielectric strength

1,500 V RMS

Temperature range

-40 to +105 °C

Construction

Open-frame chassis mounting

Flying leads

Primary and secondary leads at least 7 in or approximately 178 mm long

Dimensions

Approx. 82.6 × 52.4 × 50.7 mm according to drawing dimensions A × B × C

Mounting

Approx. 71.5 mm mounting centres; mounting-hole diameter approx. 4.75 mm

Shipping weight

Approx. 0.68 kg according to Hammond

Connections

Primary winding

Brown and blue to the two output-valve plates, red centre tap to the high-voltage supply

4 Ω output

Black common and yellow 4 Ω tap

8 Ω output

Black common and green 8 Ω tap

16 Ω output

Black common and white 16 Ω tap

Comparison with the Hammond 1750F

Hammond 1760F

6.95 kΩ plate-to-plate, 15 W, paper wound, with 4, 8 and 16 Ω outputs

Hammond 1750F

6.95 kΩ plate-to-plate, 15 W, paper wound, with an 8 Ω output only

Selection and installation notes

Reference 49969 or 049969 supports part identification but does not replace verification of the exact Blues Junior version. The mounting, lead arrangement, speaker impedance and negative-feedback circuit must match.

Connect the speaker to the tap carrying the same nominal impedance. A mismatch changes the primary load reflected to the output valves and can significantly affect current, output power and distortion behaviour.

The 15 W figure is the transformer's rating. Actual amplifier output depends on the supply voltage, bias conditions, valve condition, feedback and complete circuit.

In amplifiers using global negative feedback, check transformer phase after replacement. Reversed primary connections can turn negative feedback into positive feedback. Insulate every unused secondary lead separately.

Lethal voltages may be present on the primary wiring. Installation and testing require suitable expertise, a disconnected mains supply and safely discharged filter capacitors.

Questions about selection and use

Which output transformer suits a 15 W Blues Junior output stage using two EL84 valves?

Hammond 1760F is the documented multi-tap version for compatible Blues Junior output stages. It provides a 6.95 kΩ plate-to-plate load, a 15 W rating and 4, 8 and 16 Ω outputs; amplifier revision, mounting and feedback must match.

Which output transformer provides 4, 8 and 16 ohm taps with a 6.95 kΩ plate-to-plate load?

Hammond 1760F combines a 6.95 kΩ centre-tapped primary with three speaker outputs and a 15 W rating. Black is common; yellow, green and white provide 4, 8 and 16 Ω respectively.

Can the Hammond 1760F replace the Hammond 1750F?

Yes, the Hammond 1760F can replace the 1750F in compatible circuits when the primary load, rating, mounting and phase match. The 1760F adds 4 and 16 Ω outputs to the 8 Ω connection.

Is the Hammond 1760F intended for Fender reference 049969 or 49969?

Yes, Hammond currently lists the 1760F for Fender reference 49969; an official older Hammond selection guide writes the same reference as 049969. The exact amplifier revision must still be checked.