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GMB · 19th Feb 2006, 8:51 pm

The 967 example shows how important it is to get the correct revision of the cards, hence I now publish a list of known revisions. It is perhaps a pity that Mullard didn't think to duplicate 967B as 967C so as to ensure that the old cards were thrown away! The mistake seems to be down to this single diode having 2 pins for the one anode. You can see how this could have been mistaken for being a double diode. During tests of double valves the unwanted sections are often grounded out to avoid interference effects. The difficulty with this error is that it only becomes apparent when the valve is in the socket since the short-out flows though the valve base.

19th Feb 2006, 8:51 pm	#33
GMB Dekatron Join Date: Aug 2003 Location: near Reading (and sometimes Torquay) Posts: 3,095	Re: Mullard Valve Tester Card Project The 967 example shows how important it is to get the correct revision of the cards, hence I now publish a list of known revisions. It is perhaps a pity that Mullard didn't think to duplicate 967B as 967C so as to ensure that the old cards were thrown away! The mistake seems to be down to this single diode having 2 pins for the one anode. You can see how this could have been mistaken for being a double diode. During tests of double valves the unwanted sections are often grounded out to avoid interference effects. The difficulty with this error is that it only becomes apparent when the valve is in the socket since the short-out flows though the valve base.