Amplifier, Modified, Ex US Military
Radford Electronics Ltd.; Bristol
- Country
- Great Britain (UK)
- Manufacturer / Brand
- Radford Electronics Ltd.; Bristol
- Year
- 1948 ?
- Category
- Audio Amplifier or -mixer
- Radiomuseum.org ID
- 360430
- Number of Tubes
- 7
- Main principle
- Audio-Amplification
- Wave bands
- - without
- Power type and voltage
- Alternating Current supply (AC) / 110 Volt
- Loudspeaker
- - This model requires external speaker(s).
- Material
- Metal case
- from Radiomuseum.org
- Model: Amplifier, Modified, Ex US Military - Radford Electronics Ltd.;
- Shape
- Tablemodel, Box - most often with Lid (NOT slant panel).
- Notes
-
In December 1948 Radford advertised surplus US military 25 W TG10 Keyer amplifiers modified to work with a microphone or gram and a transformer to work from 110 V to 230/240 V mains.
This amplifier featured:
Circuit Topology- Output Stage: Push-pull configuration using two 6L6 power pentodes, capable of delivering 25 watts RMS.
- Phase Inverter: A 6N7 dual triode likely served as a split-load phase inverter, enabling balanced drive signals for the output stage.
- Preamp/Driver Stage: Two 6J7 pentodes (possibly RF-type valves) handled initial signal amplification and tone control integration.
- Power Supply: A 5U4G rectifier tube in a choke-input or capacitor-filtered design, originally configured for 110V AC. An optional auto-transformer allowed operation on 210–230V mains. 21/- extra.
Key Features
- Input Flexibility: Modified to accept microphone and gramophone inputs, with adjustable tone controls for broader usability.
- Output Options: Multi-tap output transformer supporting 4 Ω, 8 Ω, and 15 Ω loads, reflecting adaptability for diverse speaker systems.
- Low Distortion: Early emphasis on precision, with distortion levels low enough to necessitate custom measurement tools—a hallmark of Radford’s engineering rigor even in this era.
- Cabinet: Mounted in a smart black crackle carrying case.
- Price: £7/12/ 6 with valves.
These designs laid the foundation for Radford’s later hi-fi innovations, combining pragmatic reuse of wartime hardware with thoughtful circuit optimisation.
- Price in first year of sale
- 2.63 GB £
- Mentioned in
- Wireless World (The), London (WW, 79) (Dec 1948, Page Ad 56.)
- Author
- Model page created by Gary Cowans. See "Data change" for further contributors.
- Other Models
-
Here you find 32 models, 25 with images and 10 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Radford Electronics Ltd.; Bristol