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PY32

Sensibly equivalent to:
PY33 U291
See also:
Valves and their Habits - PY33: New Rectifier for Television Receivers
    
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This exhibit is an early PY32 rectifier. The Y designates this as a half wave rectifier and later examples certainly are. This exhibit has two valve systems in the envelope. The heaters are wired in series and both cathodes are strapped together internally but the anodes appear to be brought out to separate pins. Later production PY32s used a tubular envelope and a glass disc construction together with a single electrode system.
Peter comments that he has tested many PY32's and generally the older style twin cathode versions last longer than the later single system valves.
The PY32 is an HT rectifier for television receivers. It operates directly from the mains input and with a series resistance of 25 Ohms it will feed a reservoir capacitor of 100 µF.
From a Mullard press release in February 1956; The Mullard PY32 is a new half-wave power rectifier valve for use in television receivers with series connected heaters. The valve has a maximum rated output current of 275 mA, a typical DC output voltage being 190 V when the valve is supplied direct from AC mains of 200 V.
The PY32 was replaced by the PY33 that featured greater maximum current and twice the reservoir capacitance, suggesting a better surge rating and therefore a more emissive cathode.
The 300 mA heater was the standard for TV receivers from the 1960s.
The classic envelope is 40 mm in diameter and, excluding the IO base pins, is 94 mm tall.
References: Datasheet & 1040. Type PY32 was first introduced in 1955.

 

Pin Connections
IO
1
2
3
4
5
6
7
8
-
h
a
-
a
-
h
k

 

Absolute Maximum Operating Conditions
Rectifier
Vh
Ah
Va
mAa
29
0.3
250
275
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated April 17, 2014.
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