The History of the EL-34 and other Pentodes and Beam Tetrodes.

[costis_n]

Well, If you search for Fantasia Amplifier, you also get the lower 2 racks (the final stage). That's all I know, I just saw it some time ago and thought it was odd to have a Philips tube in there...

I need that system.

"I'm changing the climate, ask me how" !!!!

 

[v4lve lover]

The B443 is the first output pentode made by the dutch Philips.

 

[mvd]

The B443 is the first output pentode made by the dutch Philips.

Yes, mentioned first in September 1927

B 443_UX4pin, Tube B443_UX4pin; Röhre B 443_UX4pin ID53758,

B 443_4pin, Tube B443_4pin; Röhre B 443_4pin ID27434, Vacuum

B 443, Tube B443; Röhre B 443 ID1670, Vacuum Pentode

and very rare with three sidecontacts on the socket:

B 443_3SC, Tube B443_3SC; Röhre B 443_3SC ID53582, Vacuum Pe

Text of the Datasheet from Radiomuseum translated to English:

"First output pentode, on market Sept. 1927
Equivalent types: RES174d (Telefunken), L415D (Valvo), PP415 (Tungsram)
Successors: B443S, L416D, RES164
The B443 is the first produced output pentode of the world, introduced by Philips in September 1927. It's amplification and its power output was much higher as with an output triode of equal size. The B443 has established the replacement of output triodes by multiple-grid output tubes. The equivalent Telefunken type RES174d appeared in 1931.
[Jacob Roschÿ, 2003-Jan-14]"

Best regards
Michael

 

[405man]

Having read through this posting and some of the links it has reminded me of a question regarding the KT88, The KT88 is often refered to as a beam pentode in the GEC litrature, what is a beam pentode and how does it differ from a beam tetrode

Stuart

 

[Yvesm]

Are you sure of that ?
I always beleived that the "KT" prefix was for "KinkLess Tetrode".

Tetrode stands for four active electrodes, the "Kink" caused by secondary plate emission was suppressd by carrefully aligning G1 and G2 and adding "beam plate" to constrain the electron beam away from their support rods.
This is detailled in the O.Shade paper from RCA.
He clearly explains what is "secondary plate emission".

Some consider this beam plate as an additional electrode and thus count five calling them Beam Power Penthode.

While the name Penthode or Pentode was probably patented by Philips ? ?

Yves.

 

[barrymagrec]

I always understood that the Beam Tetrode was developed to overcome the power Pentode patents held by Plilips / Mullard. When I was about 12 years old (a very long time ago) my dad told me that "a Beam Tetrode is just a Pentode with a funny shaped suppressor grid" Seems to be fair comment.