Pye Piper
Written by Bryce Ringwood   

The Pye Piper is a simple Mid 50s Medium Wave only 5 valve superhet using series heater valves. The valve line up is UCH42 mixer, UF42 intermediate frquency amplifier followed by UBF41 detector/1st Audio. The output is a UL41 with UY41 rectifier. If you add up the heater voltages, they come to 120 volts, which would be OK if it was an American set, but it isn't.Pye Piper

This means that we have to drop 110 volts to get the valve heaters to heat. Originally, this feat had been achieved with a large 930 Ohm dropper resistor plus a smaller resistor to drop the HT voltage a little. Both of these had perished in the course of time.

I replaced them with a 1K 20 Watt and a 470 Ohm 10 Wat resistor soldered across the leads of the original "dropper". At one point I considered simply using a 110 volt transformer, since the set worked happily from 110 volts without any huge dropper resistors.

Working happily is a relative term. Actually, it was far from happy. The set had been constructed on a 1950s printed circuit made from SRBP (Sythetic resin bonded paper). The tracks had decided they didn't want to remmain soldered to the valve bases and the all important track containing the heater chain had become open-circuit.

Interestingly, the set had a permeability tuner which worked very well. Originally there seems to have been no antenna connection.Pye Piper Circuit Board

The sound quality was quite good from the small elliptical Goodman's loudspeaker. The UL41 audio output valve was fortunately in good condition - these valves are becoming scarce, I believe.

The inset shows the SRBP printed circuit board.

 

 
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