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BTH CRYSTAL SET AND BBC HEADPHONES, 1920's
This is the BTH Type 'C' Form 'A' twin detector crystal set manufactured by British Thomson Houston Ltd. in 1924. It bears the BBC/Post Master General stamp marked with the GPO Reg. No. 106.* The lid carries the instructions for use. The date of manufacture is printed in the lower left corner of the instruction card. This crystal set was manufactured by BTH from 1922 through to 1925.
*All manufactures were legally bound to obtain a licence from the Post Master General, before producing their Wireless Sets.
The set is housed in a walnut cabinet and features variometer tuning, twin cats whisker detectors and selectable aerial coupling.
A variometer is a rotary variable inductance typically used for aerial tuning
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- As a point of interest the BTH type C also refers to a 35mm 1940's cinema projector by the same maker.
.......... malcolm bell, surbiton, 5th of November 2011
- I too have one of these. The double crystal arrangement is certainly very useful and playing it directly (no amplification)into my BTH horn loudspeaker I can hear broadcasts at the other side of the room! It's amazing to think of the transmitted power, listening as I am, at a distance of 20 miles from the transmitter.
.......... Peter Scott, Edinburgh, 13th of November 2010
- I have one of these twin crystal sets and various headphones. By switching between each crystal detector, the best signal could be selected, then the other crystal 'tickled' again to try to get an improved signal. A very simple and effective idea. Lovely set.
.......... David Mills, Menai Bridge, Anglesey, North Wales, UK, 28th of November 2009