Triode - Tetrode - Pentode - (What comes next)

** Nope - that particular combo is called a "twin triode". ** That is a tube with eight tentacles. ** Eeeeeeyep.

** Look up "pentagrid converter".

Has 7 electrodes.

** Would never have guessed........

... Phil

Photo multiplier tube, contains a cascade of "anodes".

Also some special oscillator/mixer tubes, Octode just means 8 electrodes tube.

How about nixie tubes?

Enneodes (7 grids+anode+cathode) such as EQ80 were mainly used as FM detectors.

Heptodes, hexodes,octodes and other tubes with a lot of grids were often used as multipliers, the first control grid reduced the original electron flow from the cathode and the second control grid modulated the remaining electron flow, thus producing the product of the control signals (each having a multiplication factor 0..1).

The additional screen and suppressor grids are needed to keep the control grids separated (independent) and removing the electrons that are not intended to flow to the second control grid or anode.

And the reason they're so noisy is the partitioning of the cathode current between the plate and the second grid (which functioned like a partly-transmitting anode for the oscillator section and a cathode for the mixer section). The partitioning adds partial shot noise to each current.

Cheers

Phil Hobbs

Here's a partial list:

Diode Triode Beam triode* Tetrode Beam tetrode Pentode Hexode Heptode CRT dual-beam mixer

There are "space charge" pentodes that bias the innermost grid positive and control the tube with one of the outer grids -- with a different grid arrangement. There are beam tetrodes (i.e. the 6L6 and it's relatives), there are converter heptodes, that 'act' like a triode stacked with a pentode, there are mixer heptodes, there's the 6K8 hexode that you refer to -- and that's not getting into tubes that display things, like CRTs and magic eye tubes.

Get books. Get tube data books, get old electronics magazines, get old engineering textbooks. Read 'em. You'll find all sorts of interesting information about what was out there.

• I don't know what that is, but I've seen reference to it

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

And electrostatic deflection CRTs.

ftp://jjlarkin.lmi.net/547_crt.JPG

John

ng

There were also octodes & nonodes. The nonode was an interesting concept, the idea was that every valve in the set was the same type, and connecting up its electrodes differently enabled it to do the full range of jobs requiered in a radio. The point was to solve the spares & serviceability problem, with nonode equipment far less quantity of spares could be far more useful, and if necessary a set could probably be operated on phones with the audio output valve used to replace whichever one had died.

AFAIK it never caught on though.

NT

I don't know if it counts but I have 2, 12 element photo multiplier tubes sitting around my place worth some money..

Jamie

On a sunny day (Mon, 27 Dec 2010 13:41:50 -0800 (PST)) it happened Tabby wrote in :

It was a no-no de.

:)

I think the pentagrid converter was the max..7 electrodes after counting cathode and anode.

...i do not think he wanted to include such "oddities" as motophotopliers or nixies (with or without magnetics).

Now you mention it, heptodes and hexodes were in existance, but the dim memory, rescued by your mentioning, indicated they were rare / rarely used (and not for long).

..hence the well-known term "partition noise".

On a sunny day (Mon, 27 Dec 2010 22:41:05 -0800) it happened Robert Baer wrote in :

ECH81, very common in Europe, this one:

Was used in many radios as oscillator (the triode part) and mixer (the heptode part). There was also a UCH81 (series heater) for cheap radios without mains transformer.

VERY common tube. milions were in use.

At least in Europe ECHnn and UCHnn triode heptodes were common, the triode was the local oscillator and the heptode was the mixer.

Due to the very high background band noise on LF, MF and lower part of the HF band, the high heptode noise was not an issue, when even a semi decent outdoor antenna was used.

On the upper part of the HF band and in the VHF band (FM), the band noise is low and the heptode noise would be unacceptable without one or two triode RF stages before the mixer, making a heptode mixer less attractive alternative.

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

Mine's fancier:

Spiral wound deflection plates, with ground planes on either side, and the pitch and width of the spiral varies along the path of the beam. I can't imagine how much pain they went through to get that right.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

I have a CRT from a Tek 519, 1 GHz bandwidth. This scope had no vertical amp, just direct input to the single-ended deflection plate structure. The deflection goodies are inside a metal box, so it's not that interesting to look at.

Look up the horizontal system schematics if you can find them. Bizarre.

John