GMB's Vintage Technology Web Site

22nd December 2022
Formerly at

A great deal of valve technology was developed over a very short period from the mid 1930's to the end of World War II thanks to the realization that this would make up for the country's smaller military strength. It built on the early success of basic radio equipment first used on a large scale during World War I. The most sophisticated of this was carried by aircraft. Much of it works in a simple but clever way making maximal use of basic technologies. Films and stories of WWII, both real and fictional, show very little of this electronic warfare as it was all top secret. Some of these old systems moved to civilian use after the war, in some cases almost in their original form, still in use to this day.

Air Ministry equipment numbers including some Power Units and now with some Aircraft Radio Installations

Most valve and early solid-state equipment continues to remain serviceable, partly because there was less use of specialist parts than today, the basic components are still made, and also because there are still stocks of replacement valves (some are still in production). Actually it is modern equipment that is difficult to service, thanks to the use of custom ICs and computers and the trend towards withholding technical information. My rule of thumb is that anything built before 1980 is probably repairable but after that it mainly depends on the availability of replacement modules. Modern equipment mainly has a finite life due to the inevitable loss of data storage in EPROM and Flash memories.

The most common reason for old equipment not working is failure of capacitors*, not valves. Here are a few manuals and circuits for some old equipment (and some not so old). Note that this is supplied on the understanding that there will be inaccuracies, and some of these may only be specific to actual items that I own, and that this information is for your own use and will not be distributed to third parties.

*Coming eventually: my research notes on a technique to restore paper capacitors to working condition.

Introducing vintage agriculture as the Little Hill Meadows project gathers pace.

Linear Amplifier Model 122CExtracts from the manual for this valve distributed amplifier using eleven 4CX250B!
Lafayette CR Analyzer TE-46Measures capacity, resistance, transformer turns ratio and insulation leakage. Also handy for reforming electrolytic capacitors.
PACO C-25 in-circuit capacitor testerThe vintage precursor to the ESR meter, this can test a capacitor for being open circuit or shorted out without removing it from the circuit.
Hunts Capacitor Analyser and Resistance BridgeA classic capacitance and resistance bridge.
Marconi TF2701 in-situ bridge graphsReference card for the TF2701 bridge - for interpreting the phase correction knob settings.
Jason Stabilised Power Supply Unit PP-20Variable floating 200-400V and 6.3V power supply.
Griffin electrometer (solid state)Solid state electrometer.
Reforming Unit, Electrolytic Capacitor, No. 1The Air Ministry solution to reforming electrolytic capacitors.
Dawe StroboFlash 1200EA vintage neon stroboscope with built in calibrator.
Advance RF Signal Generator SG62 with SG62A updatesHF signal generator covering 150KHz to 220MHz.
Advance DVM5 Digital VoltmeterAccurate autoranging 4-digit bench digital multimeter.
Review (1937) of the Mullard Master Test BoardSee what the trade thought of Mullard's first card-programmed valve tester.
Manual for the Mullard Master Test BoardThis is a compilation of information from the Mullard MTB user manual and a German technical manual for the similar Cartomatic.
Circuit of Mullard Master Test Board / Philips CartomaticA version of the circuit, coloured to highlight the function of the cards.
1937/8 Service Equipment Buyers' GuideList of the best test equipment available at the end of 1937.
Circuits of Air Ministry Valve Tester Type 4 and 4ACompare the circuits of these two early versions of the Air Ministry Valve Tester.
Circuit of Marconi TF2331/A distortion meterTF2331A circuits - unsplit
AKAI 4000DThree-head stereo reel-to-reel tape recorder user manaual and circuit diagram.
Eddystone 770RRedrafted circuit diagram of the Eddystone 770R VHF communications receiver with component values added.
Farnell MPUFarnell stabilised voltage supply type MPU (0-6V 0.5A psu) manual and circuit
Farnell "S" series stabilised power supply unitsManual and circuit for a range of power supplies up to 50V and 50A
Clansman RT351 150Hz tone adjustmentThis is my "notes to self" on removing the RT351 from a UK/VRQ301 and taking it apart to adjust the 150Hz squelch tone level.
B2 coilsHere are some details of the coils for the B2 "spy radio".
RAF Wireless 1918-1923This document was made from photos that I took of the Royal Aircraft Establishment's 1923 compendium of circuits diagrams of RAF radio equipment from 1918-1923.
Soviet RPS receiver technical manualThis is my unfinished translation of the technical manual for the Soviet RPS receiver which is an aircraft radio the USSR put into service just after WWII (about 10MB).
The manual for the Racal TRA931P or Syncal30PThis is the version or Syncal-30 with programmable channels. NB: renew the memory retention battery on the channel board before vapours from it damage other boards!

I am currently trying to build the definitive database of cards for the Mullard High-Speed Valve Tester. There are still many of these old testers about but most sets of cards are incomplete. If you own one of these testers then please check out the Mullard High-Speed Valve Tester Project

I am also recording the cards of the Mullard Master Test Board type 7629 also known as the Philips Cartomatic GM7629. If you own one of these testers then please check out the 7629 CARD PROJECT

MHSVT information

E7600 - the first of this series

E7600/3 - has a number of changes

E7600/4 - the final version (?)

CT80 - the military version. This manual also has the best descriptions of how the tester works.

Circuits for E7600, E7600/3, E7600/4 and CT80

The TEST cards (solid colour) as actual size PDF in solid colour, suitable for duplex printing on thin card and thick laminating to make replacement cards.

The TEST cards (line-drawn black) as actual size PDF, best for use as template if making a card from sheet.