The PY800 was one of the last rectifiers of its type to be developed and is based on the PY81 from 1952. It was specifically built as an efficiency diode for television line scan in sets using 110° deflection angle tubes.
Considerable energy is fed to the line deflection coils and this has to dissipate during flyback. The efficiency diode channels this energy back to the supply rail smoothing capacitors for use on the next line scan.
The rectifier is specified as having a peak inverse voltage rating of 5,750 Volts, and a peak current rating of 450 mA. For sine wave use an input voltage of 1,500 Volts at 175 mA could be rectified. No voltage drop is quoted so the dissipation can not be given.
Telepart is a Willow Vale Trade Mark. We have a multi box carton with both the company name and the Telepart logo present. It can be found here.
The anode is bright on the inner face as can be seen from the turned-out ends.
The additional heater/cathode insulation required is in the form of an insulated helix inserted into the cathode tube before the heater is threaded through the centre.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 76 mm tall.
References: Data-sheet & 1040. Type PY800 was first introduced in 1961. See also1961 adverts.
