Why the use of American valves

[Terry_VK5TM]

Just as a bit of history, I was given some old valve gear a couple of years ago and this valve is inside a GDO that is amongst said gear:-

[Peter.N.]

They would have been nice and clean. It was in the '50s I lived and worked in Kent, as we were KB agents I use to visit the factory fairly often with under guarantee work.

The valve factory used vast amounts of liquid oxygen for some reason and I remember being there and seeing it being discharged from a tanker, the pipe was completely covered with frost and it looked as though it was snowing underneath it.

I also used to maintain the PA system at the Vegetable parchment mills in St Mary cray.

Peter

[Synchrodyne]

Originally Posted by G8HQP Dave

Australians seemed to use American names even when using European types.

I suspect that the Australian market preference for the American naming system could have been one of the reasons why Philips obtained American registrations – and names - for many of its valves in the late 1940s and 1950s. One or two, such as the 6AN7 (ECH80) might have seen more use in Australia than in Europe. By the late 1950s Amperex (USA) was selling some of the Philips TV valves, such as the EF183 and EF184, under American designations. (I think that Zenith was a user of these.)

AWV had an association with Osram as well as RCA, so also offered some Osram types in Australia. One of those was the X79, which AWV registered as the 6AE8. Evidently some of the Australian setmakers preferred to use triode hexode/heptode AM frequency changers rather than self-oscillating pentagrids, and such a valve was never made available in the American miniature range.

The basis for the Brimar UK valve range was “British Made, American Range”. But it also had to add valves that were not in the American range in order to meet European requirements. Unsurprisingly, one was the 12AH8 triode heptode. This was done with a split heater to make it suitable for use in both 6.3-volt and 150 mA series-string heater systems. Brimar also had its own designation system, an example being the 8D3, which was its version of the Osram Z77. But Cossor did the American registration for this valve, as the 6AM6, and then Brimar used this name. Having a Z77 look alike appeared to be seen as essential in the UK in the late 1940s, even where valve makers had their own broadly similar high-slope VHF pentodes. Thus Mullard had the EF91 (Z77) as well as its own EF42 (and a bit later, the EF80), and Mazda had the 6F12 (Z77) as well as its own 6F13 (and later, the 6F1).

That even those European valve makers who had a leaning towards cloning American types – obviously Brimar and to some extent Osram – went their own way with VHF pentodes might have been because they were looking for something better than the standard American receiving miniature in this class, namely the 6AG5 (Pro-Electron EF96). It was 1949-50 before better VHF valves were added to the American series, the 6BC5 (a progressive improvement and the 6CB6 (a big step, although still described by RCA as based upon the 6AG5).

The Brimar 6BR7 started life as the 8D5, but in this case I think – but don’t know for sure – that Brimar did the American registration. I imagine that Brimar was prompted to develop the 8D5 as an own-design as there was no counterpart (low-noise, low-hum AF pentode) in the standard American receiving series. For other than low-level signal work, American practice was to use the 6AU6 sharp cutoff HF pentode for AF purposes. The 6AU6 was essentially the sharp cutoff counterpart to the 6BA6 remote cutoff HF pentode, with a multipurpose mission but notably used as an FM limiter in domestic receivers. The 6AU6 had no direct counterpart in the European series (although it had Pro-Electron registration as the EF94). Rather, in European practice, it was customary to default to a VHF high-slope pentode (such as the EF80) where a sharp cutoff valve was required for an HF application.


Cheers,

[joebog1]

I am probably a bit younger than some here (66), but when I started playing with electronics ( about age 8 or 9) we really only had American numbers here. At least the "common " radio types. Octals were American numbers, but most signal and RF valves were already noval and widely used. We didnt have TV untill about 1960 or so, but that didnt get into the country untill I was about 14 or 15. WE never had a TV at home until my sister bought mum and dad a colour set in about 1980. I did do lots of repairs on old black and white sets though, even as a kid and had several mentors from the radio branch of the Snowy Mountains Authority. When I left home and started uni it was all full steam ahead for sand, although I was never really interested in them I did finally learn a little about them new fangled germanium thingies, soon to be raplaced by silicon.
Even today reading this forum I have to go the R-type.org or Franks electron pages to even understand what some of you are talking about with valve numbers.

American numbering is more logical to me, a valve number starting with 1 is 99% sure a 1.5 volt battery valve, a rectifier will most likely be a 5 something or other ( as opposed to damper diodes which were mostly 6 volts, or a 1S2 or 1B3 which is an EHT rectifier) . I guess its what you grow up with.

Joe

[Synchrodyne]

The Pro-Electron valve naming system strikes me as more informative than the American system in the absence of prior specific designation knowledge.

For example, from “EF89” one may deduce that the valve has a 6.3-volt heater (the “E”), is a small-signal pentode (“F”), has a noval base (“8x” number) and is of the remote cutoff type (odd final digit, in this case 9, within the 8x series). There are four definite points of information.

On the other hand, 6BA6 indicates a valve with a 6.3-volt heater (leading “6”) and 6 accessible electrodes. The latter is characteristic of pentodes with separate suppressor grid pinouts, but it is also characteristic of heptodes (with internally connected suppressors, e.g. 6BE6, 6BY6) and of conventional AM radio double diode triodes (e.g. 6AT6, 6AV6). So there is really only one point of definite information.


Cheers,

[Peter.N.]

Never got on with american valve nomenclature but I knew what all the common ones were. My earliest experiences were with 6SN7's and 6V6s and as my finances improved 6L6s. On the radio front the 0.3 amp radio range, 12 .... 25 and 35 .. and the weird, at the time 117Z4 that would run directly from the US mains for battery/mains sets

I seem to remember that early KB sets used Brimar valves, which is not strange as they were made next door, but I don't remember any others except English Electric perhaps

There were lots of equivalents for the much used EF91 was the US one a 6AM6? I know there was a Marconi Z77 and a Mazda 6F12.

Why can I remember that but not what I did 5 minutes ago?

Peter

[Synchrodyne]

6AM6 was the American name for the Z77, but the 6AM6 was not an American valve. As I understand it, Cossor did the American registration.

Also, as far as I know, the Osram Z77 was the prototype for this group, the others being clones.


Cheers,

[Peter.N.]

Thanks for that, I was sure someone else used them, although the pre war Cossor's used Mullard, FC4 etc.

Peter