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spike_petar 30th March 2004 10:08 PM

old tubes
 
First of all, since this is my first post i would like to say hello to everyone on this forum!

Now i have a question,
i found a few tubes from an old radio at my grandma's, and i was wondering if they could be used to make a phono preamp, or a headphone amp or anything for that matter...

the tubes are: EAF 42 , ECH 42, EL 41, 273, AZ 1

thanks

dhaen 31st March 2004 08:03 AM

Hi,

Welcome to the forum :)
Use Frank Phiipes site:
http://www.mif.pg.gda.pl/homepages/frank/vs.html to look at the data on these valves. You'll find the first 3 (don't include spaces). The last 2 don't sound like standard numbers.
Sorry to say are not paticularly useful valves, and they use a socket format that was not popular (B8A), so unless you saved the sockets, it may be difficult to get more.

If you have a socket, or can fabricate something, I suggest you just use one of these (perhaps the EL41) to get a "feel" for valves. Just make a voltage amplifier, and put some audio through it. If you like it, then invest a small amount in some valves that are more useful.

Colt45 31st March 2004 11:04 AM

Dobro došli

fdegrove 31st March 2004 11:16 AM

Hi,

The AZ1 is the rectifier, could be used if it still works.

273? Inconnu au batallion....

EL41 is a predecessor of the EL34, I think.

ECH42 mixer, triode + heptode.

EAF42 diode + penthode RF demodulation.

Personally I'd rather restore this radio and later build something else.

What brand is it ?

Cheers,;)

spike_petar 31st March 2004 11:33 AM

Quote:

Originally posted by fdegrove
Hi,

The AZ1 is the rectifier, could be used if it still works.

273? Inconnu au batallion....

EL41 is a predecessor of the EL34, I think.

ECH42 mixer, triode + heptode.

EAF42 diode + penthode RF demodulation.

Personally I'd rather restore this radio and later build something else.

What brand is it ?

Cheers,;)

thanks for the info...
the radio is an old Tesla 55c

bournville 1st April 2004 05:40 PM

The EL41 was the predecessor of the EL84 I think rather than the EL34...Some old UK radios did use the pentode section of the EAF42 as an audio amp (as well as in RF/IF circuits) and it seemed to perform adequately in that role.

As for the 273, if it was a BVA 273 that would be another triode-hexode tube, so it is unlikely, but a CV 273 is a UHF triode, so that is also unlikely...

beamnet 10th December 2005 11:26 AM

got here searching for heptode.

I read the datasheet for the ech21, and it states that it could be a phase splitter.

Could anyone point me in the right direction on this?

I have the guts aof an old philips with the standard set of ech21, 2xef22 and ebl21.

Wondered, for fun, can i make an amp with ebl21 for regulated supply, ech21 phase splitter and ef22 in pushpull.

That would only require a different opt, as the original opt is for the ebl21 SE


Bas

Devius 10th December 2005 02:40 PM

EF22 is unsuitable for audio use since it is a variable transconductance tube, and as output pentode is even more unusable since it is low power. The best way would be to get another EBL21 and make a push-pull amp. Maybe you can use the triode section of the ECH21 as driver, but I'm only guessing...

As for that 273 tube, are you sure that's what it says on the tube? If those are the only letters on it maybe the real name has already disappeared and that's the manufacturing code. Can you post a picture?

Also I think the AZ1 doesn't make much sense in a radio together with the other tubes, but I'm no antique radio expert. I've seen a schematic that has this set of valves: UCH42, UAF42, UBC41, UL41 and a UY41 as rectifier. The only difference between the E and the U tubes is the heater voltage.

beamnet 10th December 2005 02:44 PM

Hmmmzz.. got to do my homework better.


Err, that AZ1 is very common in old radio's

If there's still a meshplate one in there, it is worth quite a bit

Bas


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