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Valve testers

Three testers are in use to test the various valves in the collection.

Triplett 3480 valve tester




The first is a Triplett Combination Tester Model 3480. This is a 110V machine with a roll chart and a large meter. It has American 4, 5, 6 and 7 pin sockets, an international octal socket, an 8-pin loktal, B7G, B9A, a 7-lead wire-ended socket, and a miniature 6-pin socket.

Triplett 3480 valve tester




The second is a Precision Series 920. This has been modified to run off 240V. Again this has a roll chart and a fairly large meter. This one does not have a B9A socket.

RAF Mk.4A valve tester

The part numbers of this tester are: 10S/658 (left hand panel) and 10S/556 (right panel)

The third tester is an RAF Mk. 4A set. This consists of two units in a sturdy wooden case. The input voltage is selectable by a switch on the main panel and ranges from 200 to 250V.

Testing a valve is a matter of selecting the filament or heater voltage, the pin position of the cathode (if present), anode, G1, G2 and G3, and the anode and screen voltages, inserting the valve and turning on.

This set does not have a simple Goood/Bad meter, but instead relies on two controls, one to zero the meter once the valve is under emission, and the other to zero the meter when testing mutual conductance - this second control has a pointer and the Gm of the valve is read off the scale.

The tester has sockets for British 4, 5 and 7 pin valves, British ('Mazda') and international octal, US 5 and 7 pin, 8-pin side contact (e.g. EF8), large British 4 pin, 9-pin loktal, acorn, and 3-pin base (VR92 etc. diodes).

This file was last modified 12:00:03, Wednesday May 27, 2015