1750F Hammond PP Übertrager 049969 Fender Blues Junior

Hammond 1750F – 15 W output transformer for Blues Junior and Pro Junior

The Hammond 1750F is a push-pull output transformer with a 6.95 kΩ plate-to-plate primary and a fixed 8 Ω loudspeaker output. Hammond documents it for the Fender Blues Junior and Pro Junior.

Its paper winding is intended for a conventional push-pull stage using two EL84 output valves. Hammond prints the Fender reference as 49969, while the BTB article uses the six-digit 049969 format.

Suitable applications

• Repair of a Fender Blues Junior with matching reference and mechanics
• Repair of a Fender Pro Junior with the corresponding output stage
• Replacement application for the 049969 or 49969 reference format
• Push-pull stages using two EL84 valves and approximately 6.95 kΩ
• Guitar amplifiers with a fixed total loudspeaker load of 8 Ω
• New amplifiers with a fully calculated EL84 operating point

Technical data

Product type

Push-pull guitar-amplifier output transformer

Model

Hammond 1750F

Documented amplifier families

Fender Blues Junior and Pro Junior

Documented reference

Hammond format 49969; BTB format 049969

Primary impedance

6.95 kΩ plate-to-plate with centre tap

Secondary impedance

8 Ω

Transformer power rating

15 W

Amplifier topology

Push pull

Typical output-valve complement

Two EL84 valves in total at a suitable operating point

Winding type

Paper winding

Primary inductance

Approx. 3.99 H at 1 kHz, 1 V and open secondary

Secondary inductance

Approx. 8.71 mH at 1 kHz, 1 V and open primary

Brown-to-red primary DC resistance

Approx. 97.36 Ω

Red-to-blue primary DC resistance

Approx. 97.36 Ω

Total primary DC resistance

Approximately 194.72 Ω

Secondary DC resistance

Approx. 0.409 Ω

Primary leakage inductance

Approx. 7.03 mH at 1 kHz, 1 V and short-circuited secondary

Frequency response

70 Hz to 15 kHz, 0/-1.5 dB referenced to 1 kHz

Distortion

Less than 3% at 70 Hz under the documented test conditions

Dielectric test

1,500 V RMS

Temperature range

-40 to +105 °C

Lead length

At least approximately 178 mm or 7 inches

Dimensions

Approx. 82.6 × 42.8 × 50.7 mm

Mounting centres

Approx. 71.5 mm

Mounting-hole diameter

Approx. 4.75 mm

Hammond shipping weight

Approx. 0.41 kg

Manufacturing note

Made in Canada according to the current component drawing

Lead connections

Brown

First primary connection to one output-valve plate

Red

Primary centre tap to B+

Blue

Second primary connection to the opposite output-valve plate

Green

Secondary common according to the Hammond drawing

Black

8 Ω loudspeaker connection according to the Hammond drawing

Phase

Follow the applicable amplifier diagram exactly where feedback is used

Fixed 8 Ω design

The nominal 6.95 kΩ plate-to-plate load is obtained with a total loudspeaker load of 8 Ω. A different load changes the impedance reflected to the output valves and requires a new load-line assessment.

For a service replacement, compare the reference, mounting dimensions, lead colours, valve complement and feedback phase. The amplifier model name alone is not a complete compatibility check.

Comparison with the Hammond 1760F

The Hammond 1750F has a fixed 8 Ω output. The related Hammond 1760F also uses 6.95 kΩ, a 15 W rating and a paper winding but adds secondary taps for 4, 8 and 16 Ω.

Safety notes

Lethal plate and signal voltages are present on the primary circuit. Install the open transformer with complete touch protection and work only after the amplifier has been safely discharged.

Questions about selection and use

Which output transformer suits a Fender Blues Junior or Pro Junior using reference 049969?

Hammond 1750F is documented for the Blues Junior and Pro Junior with the reference printed by Hammond as 49969 and provides 6.95 kΩ plate-to-plate, a fixed 8 Ω output and a 15 W rating.

Which 15 W push-pull output transformer suits two EL84 valves and an 8 Ω loudspeaker load?

Hammond 1750F is a suitable starting point for a correctly designed two-EL84 output stage requiring 6.95 kΩ plate-to-plate and a nominal 8 Ω loudspeaker.

Can the Hammond 1750F be used in a newly designed EL84 push-pull amplifier?

Yes, the Hammond 1750F can be used in a new amplifier when the 6.95 kΩ load, 8 Ω output, 15 W rating and the selected plate and screen-grid voltages suit the EL84 operating point.

Is the Hammond 1760F a suitable alternative when several loudspeaker impedances are required?

Yes, the Hammond 1760F is the documented paper-wound alternative with 4, 8 and 16 Ω taps, while the Hammond 1750F has a fixed 8 Ω output.