Mystery Green Mazda valve numbers,

[boater sam]

Shuffling through my collection of old valves, I keep coming across Mazda MO based valves with unreadable green printing.

They are grey metallised, same shape as SP41s, and possibly the same vintage  Reluctant to just throw them away.
Has anyone an idea of what numbers they could be?

[pwdrive]

Pic's ?

Lawrence.

[Mike Watterson]

It's often quite possible to identify heater/filament and eventually terminals using a suitable PSU / meters / tester and thus the valve.
Certainly don't dump!
Admittedly easier to identify clear glass valves.

[ppppenguin]

TDSL (Duncan's Amps) allows you to search by type of base. That limits down the selection a bit if you're doing ID by trial and error as Mike suggests.

[Cardigan]

Green writing usually means they're pre-war examples: post-war the writing was black.

Off-hand they could be any of VP41, TH41, HL41DD and the series heater/battery equivalents of same.

[boater sam]

Had a search on the National Valve Museum site and came to the same conclusions.

I will get them on the tester when I have  time and patience to do the detective work. Meanwhile, pix as requested.

[Refugee]

That photo gives me a clue.
There are not enough pins fitted to the base for it to be an HL41DD.

[Geordie McBoyne]

Can't help identifying your valves but certain Mazda octal battery valves had green metallised bulbs. Valves such as the TP26 frequency changer triode-pentode for example.

Geordie McBoyne.

[boater sam]

Excellent deduction, it has only 7 pins, so its unlikely to be a frequency changer, likely to be a pentode, TH233, XP41, TH41 etc.

Its not a green valve, just green printing.

[Ed_Dinning]

Hi Gents, yes I have some like Geordie describes with green metallizing and black print, MO base and I believe this signified a battery valve.

Ed