Quote:
Originally Posted by Mike Kelly
Those meters with the test probe directly mounted on the meter , are primarily meant to used with a test panel . I cannot imagine anyone using those meters by placing the meter and its probe directly onto the valve sockets , which are mostly inaccessible and surrounded by wiring and other components . Most of the smaller valves I've seen have the anode pin on the base , the cap is , if present , is usually the control grid . I think a multimeter would be of more use for servicing wireless sets . The famous AVO meter perhaps ?
I only know of the 11 set having a test panel . The R107 sets are just not seen over here .
BTW the Australian version of that meter was made for the 11 set specifically . The Aust. meter isn't listed in any other wireless set parts list as far as I know .
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Hmmm...
Having just looked at the R107 working instructions it gives the expected cathode voltages using an Avo Model 7, so you may be right on that score - I remain convinced that the R109 was issued with the pocket voltmeter for faultfinding, but the voltages were measured on an internal tagboard; I shall have to dig for that manual.
My WS11 manuals list the pocket voltmeter and its case, with a footnote stating "Normally carried in Cases, Spare Parts, No.5B". The manual is dated 22nd Nov 1939 and internally notes"January 1939, amended 20th January 1939, revised and reprinted 10th February 1939". It has an addendum sheet in the back that shows the pocket voltmeters to be worse than I first thought! (23rd November 1940) ...it has become necessary to decrease the resistance of the Voltmeter, Pocket, No.2 from approximately 300 ohms to 125 ohms. The new type of voltmeter will be designated Voltmeter, Pocket, No.3...
It then gives a table showing the different readings for each test point if the No.3 is used.
The pocket voltmeter may well have been introduced for the W.S.11, but I suspect it was found to be a very useful tool and found its way into a lot of kit.
Earlier sets (W.S.1 and W/T sets (various)) had "Voltmeter, Pocket, 'x' Volts", where 'x' was specific to the set (6 volt or 60 volt, etc.).
Chris.
[1] On which note, Plate 13 looks quite legible and it might be possible to transcribe the text on the R.H. door of the charging switchboard.