What is a Kinkless Tetrode?
b.s...@genie.com
Kinkless Tetrode, and that this is somehow different from a
beam power tube.
Is there any real difference? Who came up with this idea?
Are any of the modern tube builders making "kinkless" tubes?
-Brian b.s...@genie.com
--
JSuhr
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Thanks
John Suhr
Le Cleac'h Jean-Michel
Brian,
Seems to me that kinkless refers to the shape of the curves (Ip versus Upk) of
tetrodes tubes for low values of Upk, in the region where the curve shows a
knee.
A tube like the 807 show such kinks on the curves.
If I remember correctly,those kinks are due to a kind of hysteresis in the way
the electric charges are accumulated and drained when the tube works in those
non linear conditions in which grid current appears and disappears (and in
which screen current is varying a lot).
A pentode doesn't show this phenomenon. Modern tetrodes like KT88, KT66
etc.are geometrically designed to avoid those kinks, may be one reason why
often they are improperly considered as true pentodes. (By the way KT88
KT66...are beam tetrodes like the 6L6 and the 807).
Best regards.
Jean-Michel Le Cleac'h, Paris, FRANCE
Martin Ackroyd
: I've heard that the "KT" in KT-66, KT-77, and KT-88 stands for
: Kinkless Tetrode, and that this is somehow different from a
: beam power tube.
: Is there any real difference? Who came up with this idea?
There is no difference. Same thing. Here's the story as I know it...
In the 1930's, Mullard had the patents on the pentode, so other
firmes had to pay royalties. EMI invented the beam tetrode as a
way to avoid paying the pentode royalties. But good ole EMI
chose not to exploit it commercially. They had a patent sharing
agreement with RCA, who immediately saw the potential and produced
the 6L6.
GEC [the British General Electric company - nothing to do with American
GE] then decided to make an equivalent to the 6L6 and, in around 1937,
produced the KT66, as a plug in replacement for the 6L6
GEC got very enthusiastic about 'kinkless tetrodes' and used the
principle to produce rf valves [KTZ63, KTW63] that were alternatives
to the rf pentodes 6J7, 6K7.
My dad was working at GEC on radio design at the time and the above
is how he told me the story.
'Kinkless' just means the anode characteristic does not have a negative-slope
region ['kink'] like the original rf tetrodes from the early 30's had,
caused by secondary electrons emitted from the anode, arriving at the
screen grid when the screen grid is more positive than the anode.
[eg like in an output tube with big anode voltage swings].
.
Using a suppressor grid [making the tube into a pentode] is one way
to make sure secondary emission from the anode does not give the kink.
Using beam forming electrodes plus careful alignment of electrode structures
is another way.
To repeat: "Kinkless Ttetrode" = "Beam power tube".
Same thing. No difference.
--
Martin A.
----------------------------------------------------
Scott Frankland
: I've heard that the "KT" in KT-66, KT-77, and KT-88 stands for
: Kinkless Tetrode, and that this is somehow different from a
: beam power tube.
: Is there any real difference? Who came up with this idea?
The kinkless tetrode is a beam power tube [1]. It differs from the
ordinary tetrode in the same way that other beam tubes do; i.e., it
provides a virtual suppressor [2]. Beam tubes differ from other beam tubes
mainly in the manner in which the electron stream is formed; i.e., in the
shape and position of the beam formers [3]. The 6L6 was the first beam
tube [3].
[1] M.O. Valve Co. Ltd. tube specification, London, England.
[2] O.H. Schade, "Beam Power Tubes", *Proc. IRE* Feb. 1938, pp. 162--176.
[3] Richard F. Shea, Editor-in Chief, *Amplifier Handbook*, McGraw-Hill,
NY, 1966.
~SF~
MagneQuest
Q: What is a kinkless tetrode?
A: Lonely
It's bad....but....I'll give a free tee shirt to anyone (in the US of A)
who comes up with a better reply. <G>.
Mike
Martin Ackroyd
: Sorry folks for the following....it must be a maytag monday around here:
: A: Lonely
: Mike
It's obvious. A Kinkless tetrode is a STRAIGHT tetrode.
[In traditional use of language, a straight tetrode is the
counterpart of a variable-mu tetrode]
--
Martin A.
"Hydrogen is not a hazardous substance.
It turns to water when exposed to flame."
Cheng-Ta Wu
If anyone know th resources of the gears of tube testers, please also
let me know.
thank you.
Cheng-Ta Wu
*************************************************************
* *
* Cheng-Ta Wu E-mail:840...@acc.kscgeb.edu.tw *
* chen...@ks.linkease.com.tw *
* *
*************************************************************
O'Connor
repect to plate voltage. The dip occurs where the plate is less than or
similar to the screen voltage. The fix for this was the suppressor grid
which then gives isolation of the screen and plate, but we no longer have
a tetrode--we have a pentode.
If the suppressor grid is replaced with "beam-forming plates" then we
have a beam power tube that does not have the plate current kink either.
Usually, the beam-forming plates are internally wired to the cathode, and
are sometimes refered to as a virtual cathode (long before virtual
reality). The English called this a "kinkless" tetrode because there were
only four grids -like a regular tetrode- but without the transfer kink.
Kevin O'Connor
Grego Sanguinetti
>Q: What is a kinkless tetrode?
>A: Lonely
One not wrapped in latex.
...keep the T, Mikey, already got one (and love it!).
oh, oh, oh second answer: One that Henry owns!!! B^)
-grego
--
---------------------------------------------------------------------------
Grego Sanguinetti, Lattice Semiconductor Corp. | Water, water everywhere,
gr...@lattice.com | but I'd rather drink beer.
craig o'donnell
> The English called this a "kinkless" tetrode because there were
> only four grids -like a regular tetrode- but without the transfer kink.
Gosh. I thought this meant Ray Davis touring with Mick Ralphs and a rhythm
section, without brother Dave.
-- "What ho, Mercutio" [Wm Shaksper]
A. Rohde
|>
|> Usually, the beam-forming plates are internally wired to the cathode, and
|> are sometimes refered to as a virtual cathode (long before virtual
|>
A virtual cathode consists of space charge (in this case: electrons). The beam forming
plates form a channel for the electrons. If the channel is narrow, the current density
is high and therefore at a place between real electrodes, the potential has a minimum: this
is a virtual cathode.
A virtual cathode exists, too, between the (negative biased) control grid and the cathode of
a usual amplifier tube.
I think there are a couple of articles in the RCA, Bell, Proceedings of the IRE etc. on this
matter.
Axel (not virtual)