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Old 19th March 2004, 09:20 PM   #11
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Hi,

Quote:
Well I am shure to get flamed for this but, Mullard is the best.
Here's your flame:

For the past 25 years at least all those Mullard EL34s were made by Tesla in Tchecoslavakia.

Once you know the meaning of date stamps and factory codes it's not that hard to figure out who made what, where and when.

Sorry to burst the bubble.

Cheers,
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Old 20th March 2004, 12:35 AM   #12
stormy is offline stormy  United Kingdom
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Quote:
Originally posted by fdegrove
Hi,



Here's your flame:

For the past 25 years at least all those Mullard EL34s were made by Tesla in Tchecoslavakia.

Once you know the meaning of date stamps and factory codes it's not that hard to figure out who made what, where and when.

Sorry to burst the bubble.

Cheers,

lol thats ok i wasnt in a bubble
When I said mullard i shude have added GB
I just take for granted people know what im talking about.

Mullard GB badged valves for other companies and if the owner didnt know the origin the you can get a bargain.

I must apolagise again my age is showing, I probably havn't bought a brand new valve for over 30 years. always NOS


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Old 20th March 2004, 12:48 AM   #13
EC8010 is offline EC8010  United Kingdom
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Stormy, I know that Scotland is fiercely independent, but do you think you could adjust your spelling etc to match that of contributors from outside these islands?
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Old 20th March 2004, 12:53 AM   #14
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Hi,

Quote:
Tchecoslavakia.
My typing and lack of proof reading doesn't exactly set examples either...Sorry.

BTW, Stormy,

What I meant to warn against is that lots of people, worldwide, pay a bundle for something they think is the genuine article, but isn't.

Cheers,
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Old 20th March 2004, 01:44 AM   #15
stormy is offline stormy  United Kingdom
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Quote:
Originally posted by EC8010
Stormy, I know that Scotland is fiercely independent, but do you think you could adjust your spelling etc to match that of contributors from outside these islands?

lol sorry spelling is a sore point with me

Heares a good link for people that maybe interested in codes


http://www.octave-electronics.com/cu...tubeinfo.shtml






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Old 20th March 2004, 04:42 AM   #16
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Quote:
Originally posted by fdegrove
The EL34 (European code) is a penthode, the 6CA7 (US code) a tetrode other than that they are electrically interchangeable.
I'm under the impression that the two technically have different power ratings; with the EL34 is only rated at 25w whilst the 6CA7 is supposed to be able to do 35w.
My understanding was that this was done to 'jump' the patent holds on the original EL34 design but not the Specs. So the North American version evolved to sub it, and added a larger Power rating for better durability.

As noted though, all other specs are interchangable between the two types.



Re: G.B. Mullard EL34

I've gotta say I'm also on Shifty's side on this one. The Mullard sounds great. <drool> ...Better have your Platinum Amex card handy though!

I haven't had much experience with current EL34/6CA7 varieties (too broke :-( ). I think I had a set of the Mullard/Tesla's that Frank was talking about. - 'Slimmies' with a dimple on the top of the glass envelope. They sounded (surprisingly) quite pleasant (though not up with the 'genuine' Mullard article )
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Old 20th March 2004, 08:01 AM   #17
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Quote:
fdegrove originally posted
The EL34 (European code) is a penthode, the 6CA7 (US code) a tetrode other than that they are electrically interchangeable.
Sorry to burst your bubble Frank, but a 6CA7 is a true pentode not a beam tetrode. They actually have a true wire suppressor grid (grid No. 3). That's also according to every Tube data book I've ever seen, GE 14th edition 1972, RCA RC-29 1975 etc. Have a look here:
www.hereford.ampr.org/cgi-bin/tube?tube=6CA7

I have seen the insides of many 6CA7's, EL34's and Beam tetrodes (6L6GC, 7591, 6JE6 etc.) which have beam forming plates. My father had several amps from the late 1950's and early 1960's with original GE 6CA7's in them. In the early 70's I replaced them with Westinghouse 6CA7's. All of them had wire suppressor grids.


Quote:
originally posted by Majestic:
I'm under the impression that the two technically have different power ratings; with the EL34 is only rated at 25w whilst the 6CA7 is supposed to be able to do 35w.
Not that I'm aware of, I believe the 6CA7's had a bigger glass bulb and larger plate structure. They're both rated at 25W. Back in the 70's and 80"s we refered to the EL34 as continental slimmies. Back then some of the EL34's were unreliable, couldn't push them near 500V without runaway unless you used a unreasonably high bias voltage, near cutoff.

Cheers everyone
Wayne
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Old 20th March 2004, 08:55 AM   #18
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Quote:
Originally posted by cogsncogs


Not that I'm aware of, I believe the 6CA7's had a bigger glass bulb and larger plate structure. They're both rated at 25W. Back in the 70's and 80"s we refered to the EL34 as continental slimmies. Back then some of the EL34's were unreliable, couldn't push them near 500V without runaway unless you used a unreasonably high bias voltage, near cutoff.
Every datasheet I've consulted seems to confirm your reply, Wayne. Curious. I *have* read the above elsewhere, but it seems the original author might have been in error themselves.
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Old 20th March 2004, 09:48 AM   #19
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Hi,

Quote:
My understanding was that this was done to 'jump' the patent holds on the original EL34 design but not the Specs. So the North American version evolved to sub it, and added a larger Power rating for better durability.
Yes and no....
The patent was bought by RCA so there was no reason for them to circumvent it.
However, in Europe this patent was circumvented for a long period.

Quote:
I think I had a set of the Mullard/Tesla's that Frank was talking about. - 'Slimmies' with a dimple on the top of the glass envelope.
If they look as you describe then they aren't Teslas either but Ei.
The Tesla are a perfect carbon copy of the original brown base Mullards with a flat (rounded) top, no dimple.


Quote:
Sorry to burst your bubble Frank, but a 6CA7 is a true pentode not a beam tetrode.
There's no bubble to burst except perhaps the fact that not ALL 6CA7s were beam power tetrodes.
Databooks don't always mention everything that's actually inside the tube for whatever reason.

Cheers,
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Old 20th March 2004, 10:57 AM   #20
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Quote:
Originally posted by fdegrove
Hi,


If they look as you describe then they aren't Teslas either but Ei.
The Tesla are a perfect carbon copy of the original brown base Mullards with a flat (rounded) top, no dimple.

Thanks for that. Always wondered where they were from.
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