THE GREAT MULLARD MAGIC BLOG — mhsvt

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...

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...

Many users found the depression of the RHS handle to operate the Mullard High Speed Valve Tester  quite wearing -  and this at a time before  repetetive strain injuries were invented - stiff upper lip, grin and bear it!    The boffins at Salfords listened and voila, the tester was modified to have a one arm bandit style operating arm, not only that, if you pulled it and your valve tested for good emission, three cherries in a line appeared on the CRT.......................................  sorry couldn't resist that one. Mullard advertised the change as ergonomics with  an added security measure, to stop customers...

Here we have a few more words on the MH-SVT from Mullard from 1951 along with a few of my own added in blue text:- This valve testing apparatus is capable of carrying out tests as similar as possible to those standard production tests to which all Mullard valves are subject. The tests are not of course as exhaustive as those carried out during manufacture but they do ensure that the valve under test is satisfactory in all respects insofar as it is within the approved tolerances of operation. Use of Punched Cards:  arrangement of the test circuit and selection of test...

In January of 1948, a group of engineers at Mullard Research Laboratories, Salfords were given the brief to design and bring to production within two years (24 months), 'a valve testing apparatus suitable for use by dealers and service engineers'.  The aim was to showcase this exciting new post war development at the British Industries Fair Radio Show in late 1950 at the Castle Bromwich, Birmingham halls.   The target was met and sure enough, on Mullard's stand at Site 64, the 'valve testing apparatus' was proudly presented to the waiting market. The design brief and the problems in meeting this requirement...