Item nr.

Knight 600C Tube Tester

American tube tester, adapted for use in Europe.

Data for Knight 600C
ProductionUSA, 1969.
1 diode.
CabinetWood. Size 37x19x27 cm.
PowerAC 230V (was 110).
DocumentsAssembly instructions.

The Design

Knight is a well-known brand of kit products. One would buy the parts and assembly instructions, and then assemble the set oneself at home. There was even a trouble-shooting service available in case it would not work. This kit came from Japan, but was assembled in the US for American use. The tube tester is of the simplest type: it only measures the emission of the tube as a percentage of what it should be. Also some short tests can be carried out.

Is a tube tester necessary or handy for a radio hobbyist? I think so, despite the unreliability of the device. Indeed, sometimes a tube may test good yet cause malfunctioning of a radio. And similarly, a badly testing tube may perform well in an actual radio. But when used with precaution (do not throw away the bad tubes immediately!!) it is a handy device.

Obtained6/1998 from person in Rijswijk.

This Object

The tester was a little bit too American for me and I sacrificed the originality and adapted it to everyday use in a European workshop.
First, the unit is supposed to be supplied with 117V of mains, but this was remedied using an old scrap power transformer (with multiple primary taps) as an autotransformer.
Then among the sockets there were a few for which I had never seen tubes, while common European sockets (Locktal, Rimlock, and P-base) were missing. I did away with two of the existing sockets that were replaced by Rimlock and Loctal, and made a converter plug for P-base.
Finally the data supplied on the roll-chart was for tubes used in America, and with their American type numbers. So I had to figure out how the tester could be set up for new tube types, and did so for about 100 often-used tubes. The result is in this manual (in Dutch, as PDF file).

Part of Gerard's Radio Corner.
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