A few pieces of commercial test equipment

Valve Tester

My friend Mike bought this for me. It's an AVO Valve Tester which uses nine-pin adaptors into which you plug the valve to be tested. I imagine it dates from around 1949.

Inside it's all integrated onto the bakelite front. A clever idea but it must have been difficult to design. Clearly a lot of labour went into making it as the transformers have every tapping under the sun. I noticed a small modification where a silicon diode has been used to replace the original metal rectifier.

Inside view

Marconi Audio Power Meter

This is an audio power meter made by Marconi

Useful for checking audio amplifiers or the output from hi-fi equipment

Nothing special, it indicates up to 10watts RMS. I had a huge amplifier to repair the other day. It cost a small fortune to fix as something like 10 MOSFET power transistors driving one of its two channels had bitten the dust, presumably when they saw a short-circuit and the owner had cranked up the power wondering why nothing was happening. As the thing was rated at a kilowatt per channel there must have been a fair bit of smoke at the time.

An old insulation test set I bought from Ringwood street auction

A pair of mains earth leakage testers bought for 50p each

from a garage sale. Both work OK.

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