8 Nov
2007
8 Nov
'07
11:17 a.m.
This may be a
UK .vs. US language difference, but to me :
A 'filament' is a thin wire, heated electircally. A heater (in a valve)
is a particular type of filament
A filament that's also the cathode (as here) is a 'directly heated cathode'
A filament that heats a separate cathode is called a 'heater'. The result
is caleld an 'indirectly heated cathode'
Some of it is context-related in the US, at least. Transformers are
said to be "filament transformers" if their intended use is to power the heater. The glow from the heater (indirectly or
directly heated
cathodes) is usually said to be a "glowing filament". Many older
handbooks show basing diagrams with "F F" particularly if it's a
directly-heated cathode. The glowing element in a Tungar bulb is
Sure. That _is_ a filament :-). Some data books use 'F F' for a
direcrly-heated cathode and 'H H' for a heater, with 'k' for the cathode
itself. Oh, and 'Hct' for Heater centre tap :-)
usually termed to be the filament.
OK, it's not thin, but I think it's a filament :-)
Finally, some call a heater a "filament" and a "cathode" the heated
emitting sleeve.
In context, I'd used 'heater' for the hot wire and 'cathode' for the
sleeve around it
It's one of those things wherein what's intended is rarely a mystery.
Exactly. If somebody talks about the 'cathode voltage' of an
indirectly-heated valve, it's clear they mean the voltage between the
emitting sleeve and some reference point/. Whereas 'heater voltage'
would normally mean the voltage between the ends of the heater filament.
"Plate" for "anode" is common usage here in all but special-purpose
devices, such as CRTs.
That is not at all common over here. Most old-timers would know what you
meant, but it would be taken as an Americanism.
Talking about CRTs, I beleieve across the Pond, the electodes are called
'cathode', 'grid 1', 'grid 2'.... 'anode'. Over here
they're 'cathode'
'grid'. 'anode 1' (or 'first anode'), 'anode 2'
('second anode')... (the
last one, the aquadaq coating inside the flare, connected to the EHT
supply, is called the 'final anode' most of the time).
-tony