THE GREAT MULLARD MAGIC BLOG — MULLARD HIGH SPEED VALVE TESTER

I was thrilled today to be contacted by Arthur, all the way from Australia who shared his memories  from 67 years ago about his dad's Dalston radio shop, Tiny for Radio and the tribulations of the shop Mullard High Speed Valve Tester (MHSVT) which I can now share with you: - We used Mullard valve testers for years and years, replacing them as they became worn out or superseded. I don’t remember the version numbers, but I would think the pictures that you show were identical to what I remember. We also had AVO valve testers, but although we still...

In early 1951, Mullard introduced a handy steel container finished in 'Dimenso' - that's posh for silver hammer finish paint. The container was designed to hold 600 cards in six separate compartments.   This number of cards would test 750 different valve types.    The container featured rubber feet and was sized to be equivalent in length to the depth of a tester so it could sit alongside - provided enough room was left to allow the clamshell top to open!   And the price for this marvel of modern engineering in March 1951 was 45s - a snip!

At the time of introduction, two 'hollow state' devices the MHSVT contained were considered exotic.   The first, the 85A1 voltage regulator is a neon filled reference two electrode device which serves to provide the MHSVT with it's reference voltage stable in normal useage to 0.17% variance and over it's entire life. stable to within 0.5% of nominal value.     The second is the DG7/5 cathode ray tube which is an electrostatic medium persistance tube .    What is interesting is that this CRT is used in this application purely as a voltage indicator, measuring various currents by means...

These were selling like hot cakes in 1951 and details of their build and performance featured in much of the Mullard official literature of the time. Here we see Arnold Polkinhorne doing something with a Philips valve voltmeter.  Just look at that fat bottle EL37 lurking on the chassis as well as a stash of more MHSVT in the background. The fun cotinues as here is Dorothy Prinkle nimbly constructing and lacing a wiring loom for a MHSVT - looks like she's using the silicon covered wire display from Phil Marrison's BVWS stall - haha!

Resuming our Mullard story in 1951, we see that Mullard is still vigorously pushing the MHSVT and that it is being received with praise by the radio & TV trade.  Here we see Chris Evan's grandad posing with his machine, in his letter to Mullard he went on to explain how he is clawing back his purchase capital outlay by charging customers "a bob" to have their valves tested - he thought about doing it for free but thought that customers wouldn't appreciate a service they didn't pay for(!) -that's the spirit!   And yes, the MHSVT really was at...