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Posted by STEVE M on

Well, Mazda were another manufacturer who wanted to stand out and indeed made their own version of the Octal base with a fatter spigot known as the Mazda Octal or MO base.    Their valve numbering system was a bit kooky too and needs some explanation. 

The typical Mazda valve type number was an alphanumeric affair comprising of; a numerical prefix followed by a letter which in turn was followed by a mumerical suffix.

The numerical prefix always indicated the heater voltage EXCEPT where 10, 20 & 30 were used which indicated the heater current draw in 0.1A.  A further exception was for rectifier valves whose designation started only with a letter - eg U31, UU5 etc.

The letter indicated the valve type with letters allocated as per the following table.

C Frequeny changer
D Signal diode or diode(s)
F Signal tetrode/pentode
FD Signal tetrode/pentode plus diode(s)
FL Signal tetrode/pentode plus triode
K Thyratron
L Signal triode or triode(s)
LD Signal triode plus diode(s)
M Tuning indicator
P Output tetrode/pentode
PL Output tetrode/pentode plus triode
U Halfwave rectifier 
UU Fullwave rectifier 

The numerical suffix was a sequentially assigned development number.

Here are a couple of examples: -

UU5 -  the 5th full-wave rectifier developed by Mazda.

20P1 - the 1st 200mA  heater output pentode developed by Mazda.

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