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KT 77 [message #9586]

Fri, 17 March 2006 17:04

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

Does anyone know if they are a drop-in for the EL 34?

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Re: KT 77 [message #9587 is a reply to message #9586]

Sat, 18 March 2006 12:46

Damir
Messages: 1005
Registered: May 2009

Illuminati (2nd Degree)

I don`t have experience with KT77 (too rare/expensive), but I have some with various EL34.

It is actually "kinkless tetrode", or beam power tube - EL34 is "true" pentode. (Is this a problem in practice - not really.)
Almost every tube manual lists KT77 as EL34 "drop in" substitute, and many people observe it like "premium" version/replacement.
You must check (and eventually fix) the bias when you install the new tubes, anyway.
Hey, if you have some source with many cheap NOS KT77 - I`m in!

http://frank.pocnet.net/sheets/086/k/KT77.pdf

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Re: KT 77 [message #9588 is a reply to message #9587]

Sat, 18 March 2006 17:40

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

D-Man; The KT 77's are being manufactured again and AES has them for about 80$ a matched quad. I was wondering if they are any good. I have adjustable bias on each tube so thats not a problem. I never heard about that they were premium tubes though.
What is it makes them better? Because it is a beam power tube?

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Re: KT 77 [message #9589 is a reply to message #9588]

Sun, 19 March 2006 01:09

Damir
Messages: 1005
Registered: May 2009

Illuminati (2nd Degree)

Hey, GEC KT66, 77, 88 series are very sought-after and expensive - see the various "confessions" of tube rollers on tube forums.

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Re: KT 77 [message #9613 is a reply to message #9588]

Wed, 29 March 2006 04:33

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Hey-Hey!!!,
I seem to remember that the KT77 had a 30W plate like a 6L6-GC instead of the 25W of the EL34 pentode. Otherwise quite intrchangeable, and it seems that the old American 6CA7 beamer had a 30W plate. Certainly the new EH beamer has higher plate diss than an EL34.

From a few folks, the new KT77 seems like a good deal. If there weren't a lot of more interesting stuff to play with, I'd still be building EL34 amps.
cheers,
Douglas

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