The oddest valve? KLL32

[Synchrodyne]

Originally Posted by kalee20

Synchrodyne is good at answering questions like these!.

Not in this case, but thanks for the vote of confidence! Mostly I’ve looked at valves from the post-WWII period, but not many at all from earlier than that.

I guess that “oddest valve” is rather a subjective concept, given that there are probably at least fifty shades of oddness. An oddity that comes to mind is the 12-volt HT car radio 12FX8 triode-heptode in the American series. In general, that is nothing odd, but it does appear to be the only American example of a miniature triode-heptode and the only American example of a post-WWII triode heptode, unusual but not odd. But then the heptode part was designed to be used as a self-oscillating mixer in the usual American pentagrid fashion. The triode was designed to be an RF amplifier. That functional combination is I think odd, particularly when one considers that the European rationale for the triode-heptode was to avoid the problems associated with self-oscillating heptode mixers.

Still in the 12-volt HT car radio territory was the 12EG6 heptode. On the face of it, not so odd, given that the American series contained at least four other 12-volt HT car radio heptodes. But these were all pentagrid converters, whereas the 12GE6 was a dual-control heptode, a not-so-odd function, for example the 6BY6 and 6SC6 from the main series were of this type. But the apparent oddity was that the 12GE6 was intended to be an RF amplifier, with AGC bias applied to two grids (g1 and g3), thus enabling a greater control range for a given AGC bias range than when one grid was controlled. I suppose that one could subtract a few points from its oddness rating by noting that the same approach to car radio AGC was used in some European designs that employed the ECH83 heptode section as an RF amplifier.

Another oddity was the 6BU8, sometimes called a dual-pentode and sometimes a split-anode pentode. It was designed for use as a combination noise-gated sync separator and noise- and line-gated AGC rectifier in TV receivers. On the AGC side, it might also have been used for systems that were noise-gated but not line-gated.


Cheers,

[Boater Sam]

Leowe 3NF, is it a thermionic IC?
How on earth did they bake it with a capacitor in it? Must be ceramic.
Who's got one?

I have some new ones of those odd American 12xxx series valves, mostly car radio I think.

[FERNSEH]

Synchrodyne wrote: "Another oddity was the 6BU8, sometimes called a dual-pentode and sometimes a split-anode pentode. It was designed for use as a combination noise-gated sync separator and noise- and line-gated AGC rectifier in TV receivers. On the AGC side, it might also have been used for systems that were noise-gated but not line-gated."

In 1938 Cossor introduced a new "split anode valve" for service as the sync separator in TV receivers. The valve wasn't a true split anode and like the 6BU8 had two separate pentode sections. The 4TSA was employed in the Cossor 54 and 1210 TV receivers. Cossor made a similar valve for use in the 1936 model 137 TV receiver, the sync separator valve was the split anode type MTS.

From the Radiopmuseum: https://www.radiomuseum.org/tubes/tube_4tsa.html

DFWB.

[G6Tanuki]

I remember seeing one of the 'split-anode' intended-for-demodulation-in-TV valves [which also had split second-grids] used as a balanced-modulator in a late-1940s SSB exciter. I think it was published in "QST".

RF to the main grid, push-pull audio to the split second-grids, a centre-tapped tuned-circuit at the output frequency across the two anodes. You got DSB out, then needed to put it through a crystal filter to slice-off the unwanted sideband.

This was before the late-1950s coming of the likes of the 7360/6AR8 'beam deflection' glowbottles - http://www.r-type.org/articles/art-055.htm

[Trifocaltrev]

Another valve similar to the KLL 32 was the European DLL 101 1.4v miniature battery valve, I have not seen a set using one of these yet.

Trevor

[G6Tanuki]

I've never seen the DLL101 used in anything, but in the late-1960s I came across a few radio-controlled-model setups which used the DCC90

http://www.r-type.org/exhib/aaa1001.htm

as a self-excited push-pull oscillator on 27MHz. No, they didn't use crystal control and the frequency did wander, but the receivers were super-regens [using either valves or the likes of AF117/OC170 transistors] so had equally wide-open-to-a-few-MHz bandwidths.

[GeoffK]

The Ferguson 215B table model has the Mullard KLL32. The portable 205B has the Mullard QP22B. The text says it's equivalent but the KLL32 can operate in AB1.The QP22B operates in Class B.

[Mr Moose]

Hello,
An interesting form of split anode tube are the beam deflection tubes that use electrostatic deflection.
https://en.wikipedia.org/wiki/Beam_deflection_tube
Yours Richard

[Boater Sam]

I've just found an EBF85 on my stock list. If anyone wants one for a Mexico Omnibus radio, see me.
Any others?

Is there such a beast as CF806 or is it a typo on my list? Perhaps the "P" fell off.

[FERNSEH]

Boater Sam wrote: "Is there such a beast as CF806 or is it a typo on my list? Perhaps the "P" fell off."
CF806? If such a valve exists it would a B9A base RF pentode with a 0.2amp heater for series chains and was registered with Pro-electron after 1960.

The Radiomuseum lists the EBF85 but offers no information. After googling "EBF85 tube valve" an EBF85 hand washing faucet came up:
https://bimobject.com/en-us/sloan_va...oduct/nst12169

DFWB.

[Boater Sam]

There is this info EBF85 on the Radiomuseum.
https://www.radiomuseum.org/r/becker_mexicoomnibus.html

Which is where I got the Mexican Bus from. Bizarre.

[ms660]

EBF85 or sale in W.W. valve suppliers:

http://www.americanradiohistory.com/...ch=%22ebf85%22

I've never heard of it before.

PCF806 was used in telly tuners.

Lawrence.

[FERNSEH]

Here's a valve that was never used in the UK and I'd imagine it's not all that common on the continent either, the Telefunken PCL81. Also was available as the ECL81 and UCL81.
https://www.radiomuseum.org/tubes/tube_pcl81.html

DFWB.

[Boater Sam]

Here is another common continental valve that doesn't grace our UK shores.

PM84 Indicator, 300mA series heater chain version of EM84.
How come the continental TVs have indicators and not ours?

[G6Tanuki]

Originally Posted by Boater Sam

How come the continental TVs have indicators and not ours?

Perhaps because the continentals had a greater availability of stations, so retuning the TV was a more-frequent activity? I can remember at least eight channels [Swiss, German, French, Italian] being available where we went on holiday in the mid-1960s.

Remember that until the early-1970s most UK TV-watchers only had two choices (three if you were lucky to live in the 'sweet spot' between two overlapping ITV regions) so the need to do much manual tuning was low.

[Radio Wrangler]

Originally Posted by G6Tanuki

I remember seeing one of the 'split-anode' intended-for-demodulation-in-TV valves [which also had split second-grids] used as a balanced-modulator in a late-1940s SSB exciter. I think it was published in "QST".

RF to the main grid, push-pull audio to the split second-grids, a centre-tapped tuned-circuit at the output frequency across the two anodes. You got DSB out, then needed to put it through a crystal filter to slice-off the unwanted sideband.

This was before the late-1950s coming of the likes of the 7360/6AR8 'beam deflection' glowbottles - http://www.r-type.org/articles/art-055.htm

Ah, the 7360 'beam deflection' valve. It also made a rather good mixer. You had to keep it clear of magnetic fields which could induce hum. You'll find one in the front end of the G3PDM receiver in RSGB handbooks from the late 60's into the seventies.

There are plenty of weird valve-like devices around. Photomultipliers, Klystrons, magnetrons, backwards-wave oscillators, travelling wave tubes (affectionately known as Twits), Geiger-Mueller tubes, Klystrodes (what do you get if you mix a ..... with a ......?), Thyratrons, Ignitrons....... etc. etc. So a double pentode with a bonus triode and an odd heater voltage is really quite tame once you open up the fool loony asylum of electronic glassware.

David

[turretslug]

The '30s also seemed to be a time of wackiness in the quest for valves that could do more and more better and better, e.g. the EF8 and EE50 as stepping-stones to the EF50. Quite a few weird and wonderful UHF generation devices, too, before the cavity magnetron ended up on the winning podium.

I recall learning about the rhumbatron and M- and O- carcinotrons, too, but have utterly forgotten what they involved....

[G6Tanuki]

Originally Posted by turretslug

The '30s also seemed to be a time of wackiness in the quest for valves that could do more and more better and better, e.g. the EF8 and EE50 as stepping-stones to the EF50..

Ah yes, "Secondary Emission". Quite a number of attempts were made by different valve manufacturers to get it to work reliably but they all seemed to give up on the idea until the appearance of 12-volt-HT valves for car radios in the 1950s, many of which used a quasi-secondary-emission approach to nullify space-charge effects.

[FERNSEH]

Originally Posted by Boater Sam

Here is another common continental valve that doesn't grace our UK shores.

PM84 Indicator, 300mA series heater chain version of EM84.
How come the continental TVs have indicators and not ours?

The PM84 was used as the FM radio tuning eye in the Ultra VR17-64 TV receiver.

DFWB.

[Synchrodyne]

Originally Posted by Boater Sam

There is this info EBF85 on the Radiomuseum.
https://www.radiomuseum.org/r/becker_mexicoomnibus.html

Which is where I got the Mexican Bus from. Bizarre.

I hadn’t previously heard of the EBF85, and I can only wonder as to what was its purpose.

The EBF80, which combined a remote cutoff RF pentode, proximate to the EF41, with a pair of diodes, was quite logical. The EBF89 was essentially an updated version, with a pentode section that was proximate to the EF89, with higher slope but retaining very low cag, enabling higher gain without the need for neutralization. (Although some makers still used neutralization for the pentode, and for the pentode-diode interaction.)

The EBF83 was the 12-volt HT car radio version of the EBF89, and might simply have been a selected EBF89. Then the obscure EBF81 had a very low slope (1 mA/V) sharp cutoff pentode.

Now an EBF85……

When I looked closely at the valve line-up of the “Mexican Bus”, my initial reaction was total astonishment (well, that’s the polite translation). Here it is:

ECC81, ECH81, EF89, EBF89, EABC80, EBF80, EBF85, ECC81, ECC81, EL84, EL84

It had an EBF89, an EBF80 and an EBF85!!!

The use of an ECC81 (rather than an ECC85) for what I assume was the FM front end looks as if it had been done to allow commonality of valve type with the AF section. A reasonable assumption is that first AF ECC81 was used for tone control, maybe a Baxandall circuit with one triode as driver and the second as anode follower, and that the second AF ECC81 was used as the driver and phase-splitter for the output pair.

But this apparent rationality is totally countered by the use of three different DDPs. The EBF89 pentode was probably used as FM 3rd IF amplifier/limiter and perhaps AM 2nd IF amplifier, with the diodes used for AM detection and AGC rectification. Or perhaps the EF89 was used as an AM RF amplifier, with the EBF89 pentode then serving as FM 2nd IF/limiter and AM IF. Presumably FM detection was done by two of the diodes in the EABC80.

The EBF80 and EBF85 look as if they are in the post-detection section. As I recall, the original Philips data for the EBF80 indicate that the pentode could be used as an AF voltage amplifier, and perhaps it was better in that role than the EBF89 pentode. But with no shortage of triodes in the AF chain (five of them), it is hard to see a need for additional AF voltage amplifiers. Perhaps then the post-detection DDP pair were part of a special-purpose circuit. Volume compression and noise-spike suppression on FM come to mind as being functions that could have been considered useful for car radios, and which might use diodes and pentodes. In American car radio practice there were DDPs with low-slope remote cutoff pentodes (e.g. 12F8) in which the pentode was used as an AGC’d AF amplifier to provide additional AGC range. Perhaps the EBF80 in the case at interest was deployed in this manner.

That leaves the EBF85. Perhaps it was used as an AF compressor. The AF AGC system would provide longer-term compression, but above that dynamic range compression may have been thought desirable. In that case one could deduce that the EBF85 pentode had characteristics desirable for the compression function, whereas the EBF80 and EBF89 pentodes were not so good in that role. One could also imagine a noise-spike suppression role in which unstretched pulses from early enough in the FM IF strip were rectified and used to blank the audio for very short periods. Perhaps a sharp cutoff pentode with switching via its (short-based) suppressor grid would have done the job there.

All speculation though – wild guesses really. Maybe the answers will surface somewhere, sometime.


Cheers,