Quote:
Originally Posted by RF Burn
That 'N' embossed on the base pretty well confirms that it is of UK manufacture. Now looking at the attached label, the Service Valve Equivalents Guide gives the CV587 as 6Q7G (USA), DH63 (MOV) and the ZA manufacturers code as 'MOV Gateshead' which strengthens the MOV (Marconi Osram Valve company) connection. Is that information strong enough to fix a result?
Brimar also copied the 'stop sign' or hexagonal border for their early valves from their USA originals, after all the company was named BRItish MAde American Range (BRIMAR) for a reason . . .
Other British manufacturers normally produced 'equivalents' or 'substitutes' to USA type valves using their own standard type numbering systems (e.g 6Q7 = EBC33, DH63; 6J5 = L63; 6F5 = H63; 6K7 = EF39, KTW63 etc.)
Also, do not forget the flood of 'tubes' from the USA during & after WW2 as parts/spares for the US and British military and on 'lend/lease' that were marked and distributed by British manufacturers.
Adrian.
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Yes, your conclussions are good enough for me.
There must have been some wide tolerances for substitution as the amplification factor and Ra for 6Q7 is ~60 and 50KOhm as opposed to 30 and 15KOhm for the EBC33.
Would that have been normal ?
I'm asking because I'm putting together a rather extensive list of settings for the B&K 607/667 emission valve-tester when testing B&K non-listed valves. The list is already some 80+ A4 pages and I have obviously no chance of testing each and every valve in-the-flesh. So, I'm depending on what cross-ref. tables and books that have been published, like The Sams-series and the RSGB Service Valve Equivalents besides data from radiomuseum.org, The CV-register etc. etc.
Unfortunately I don't have a NOS EBC33 here, actually none at all, so I won't be able to hold the readings against the 6Q7 for this valve xref, and perhaps I should be more carefull in the future about recommended substitutions that could display far off data from the original.
/Torben