Pye "Baby Q"
This battery portable set was released in March 1937. Although by this time the superhet circuit was well established, many portable radios continued to use TRF technology. The Pye
"BABY Q" is a four valve TRF set with a frame aerial, although in some respects the circuit is a little unconventional.
The valves, on B4, B5 and B7 bases are:
K50M RF amplifier
K30K Leaky grid detector
K30K First AF amplifier
K70B or Pen220 Output
The "volume" control is a special ganged unit consisting of a variable rheostat in the filament of the K50M valve and a variable capacitor providing reaction feedback around the leaky grid detector. Over the first half of rotation of the control the gain of the RF valve is controlled by the filament rheostat. Over the second half of rotation the variable capacitor provides conventional reaction.
Two ganged tuned circuits cover Long and Medium wavebands. Automatic grid bias for the output valve is obtained using a dropper resistor in the HT- return line, thus removing the need for a separate grid bias battery.
When the set was released it cost Ł8 8s.0d. complete with batteries.
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