Mazda octal 1.4volt valves.

[FERNSEH]

In 1939 Mazda introduced a range of valves with 1.4 volt filaments which had the Mazda Octal base.
FC141, SP141, H141d and PEN141. Base apart it would seem that these valves are electrically similar to the American 1A7G, 1N5G, 1H5G and 1C5G.
The Radiomuseum lists only three radio receivers that used the 1.4volt Mazda MO valves. A Brunswick, a Decca and a Ferguson.
http://www.radiomuseum.org/r/decca_2_mld3.html

The pentagrid frequency changer: http://www.radiomuseum.org/tubes/tube_fc141.html
It would appear no post-war radios employed these valves.

DFWB.

[G6Tanuki]

I'm wondering if these were intended to allow manufacturers (or users) to 'upgrade' existing MO-based 2V-accumulator-LT receivers (which would have used valves like the VP23)?

I can see the vague attractiveness to a receiver-manufacturer in being able to switch to these valves and so release an 'all-dry' 1.5V-battery radio without having to re-engineer existing chassis metalwork.

[Of course once WWII was over the ubiquity of cheap B7G war-surplus 1.4V valves - 1T4 1S5 etc - made the whole idea of using any flavour of Octal valves in portables look spectacularly dated]

[paulsherwin]

Ordinary IO lineups were still quite common for a few years postwar, but I've never come across a single set with MO 1.4V valves. Mazda were pretty much flogging a dead horse with MO by then.

[G6Tanuki]

Originally Posted by paulsherwin

Mazda were pretty much flogging a dead horse with MO by then.

True. Despite which they insisted on trying a rerun of the same losing game with their B8A valves. . .

[FERNSEH]

Actually, you can say that the FC141 was a very "unMazda" valve. Pre-war and post-war the companies' 2 volt battery frequency changer valves were triode pentodes, TP22, TP23, TP25 and TP26. In all these valves the oscillator injection grid was always G3. The FC141 is a pentagrid valve, it's safe to say it was simply a copy of the 1A7G so it's possible that Mazda did not design the valve and it is most likely was the same with all the "141" series valves.
Non of the usual adherents to Mazda used the 1.4volt Mazda octal valves, i.e. Ekco and Ultra, but I'm not sure if Murphy ever made a set that employed these valves.
And yet the FC141 on display in the Valve Museum has the typical Mazda bulb shape.
http://www.r-type.org/exhib/aaa0369.htm

DFWB.

[kalee20]

Originally Posted by paulsherwin

Ordinary IO lineups were still quite common for a few years postwar, but I've never come across a single set with MO 1.4V valves. Mazda were pretty much flogging a dead horse with MO by then.

Me neither. I do have a postwar set with 2V MO valves - really you'd expect it to be the other way round!

Shame about the MO base, the big centre spigot did allow the evacuation tube to be sunk into it, reducing valve height over the IO base, and reducing lead length reduced cathode lead inductance!