Re: Unusual open plate structure - S6F-33

[Ronald]

"Ross Matheson" > schreef in bericht
...
> OK, we've all seen those cutaway tube illustrations, and maybe even taken
> sharp cutters to a dead tube's plate structure after breaking the glass.
> This little tube has the most open plate structure I've ever seen. Data at
> http://www.mif.pg.gda.pl/homepages/frank/sheets/025/s/S6F33.pdf
> It's a special quality dual control HF pentode. The plate structure,
looking
> down from the top, would be in the shape of a U - except the curved part
is
> only a thin band joining the two straight sections, at one side. From the
> other side you can see the whole grid structure between the two plate
ends.
> This scan is taken looking into the open end of the "U", from that side.
> I don't know where this would have been used - even the data sheet says
> "Tentative" - but thought it might be interesting enough for a geeky note.
>
> RdM
> <nz not zn>
>

I thought I've seen it all with the PL802 and E55L , but this one is extreme
!!
Myabe if you take the shield out of an EF184 ..... It's hard to see the
anode trough it .

Ronald .

[Ross Matheson]

"Mikkel C. Simonsen" > wrote:

: Ross Matheson wrote:
: >
: > This little tube has the most open plate structure I've ever seen. Data at
: > http://www.mif.pg.gda.pl/homepages/frank/sheets/025/s/S6F33.pdf
:
: The "rocket brand" 6N1Ps I have are simmilar. The plate consists of two
: "U"s with the bottom ends facing the grid, so the sides are completely
: open.
:
: Does anybody know the reason for these open structures?

Good question! I was wondering why, too. Less capacitance to plate?

: Best regards,
:
: Mikkel C. Simonsen

RdM

[Fred Nachbaur]

Ross Matheson wrote:
> OK, we've all seen those cutaway tube illustrations, and maybe even taken
> sharp cutters to a dead tube's plate structure after breaking the glass.
> This little tube has the most open plate structure I've ever seen. Data at
> http://www.mif.pg.gda.pl/homepages/frank/sheets/025/s/S6F33.pdf
> It's a special quality dual control HF pentode. The plate structure, looking
> down from the top, would be in the shape of a U - except the curved part is
> only a thin band joining the two straight sections, at one side. From the
> other side you can see the whole grid structure between the two plate ends.
> This scan is taken looking into the open end of the "U", from that side.
> I don't know where this would have been used - even the data sheet says
> "Tentative" - but thought it might be interesting enough for a geeky note.
>
> RdM
> <nz not zn>

That's neat! I've always had a special place in my heart for the 6CB6
because of its open structure (never mind that it's also a useful tube!)
but this one takes the "Visible Tube Award" for sure.

Your second scan was very nice, shows it very well.

For comparison, a 6CB6 is here:
http://www.dogstar.dantimax.dk/tubestuf/pinups/6cb6.jpg

Keeping plate-to-everything-else capacitance low would seem to be the
main benefit of having such a low anode area.

Cheers,
Fred
--
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| Projects, Vacuum Tubes & other stuff: |
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[Ronald]

Still amazing .......
Most of the time "S" is much higher with such open constructions .....

"Ross Matheson" > schreef in bericht
...
> Didn't do it justice at 150dpi, lowest quality jpg.
> Here's a rescan, opposite side, 600dpi, slightly higher quality, only 30k.
> Brand new tube, had a slightly mottled film on the glass. Unfortunately,
> trying to clean it smeared some of the lettering. Oh well, price of
detail.
> Note the bottom grid spiral is slightly squashed, too :-)
> Much larger and clearer picture. Posted again at abpr :-)
> RdM

[Ross Matheson]

Fred Nachbaur > wrote:

: That's neat! I've always had a special place in my heart for the 6CB6
: because of its open structure (never mind that it's also a useful tube!)
: but this one takes the "Visible Tube Award" for sure.
:
: Your second scan was very nice, shows it very well.

Thanks!
Must remember to de-dust (and not smear lettering:) more often though!
There's a few available if anybody can think of a useful application ...

: For comparison, a 6CB6 is here:
: http://www.dogstar.dantimax.dk/tubestuf/pinups/6cb6.jpg

Wow, very similiar plate structure, indeed. Can't see any wires on those
intermediary pins though, wonder what they are doing? Just supports?

: Keeping plate-to-everything-else capacitance low would seem to be the
: main benefit of having such a low anode area.

It's the only logical conclusion I can come to, indeed, and it fits their
intended HF applications (6CB6 included).

: Cheers,
: Fred

And a fine morning to you up there in Summer:-)

[Tim Williams]

"Mikkel C. Simonsen" > wrote in message
...
> The "rocket brand" 6N1Ps I have are simmilar. The plate consists of two
> "U"s with the bottom ends facing the grid, so the sides are completely
> open.

Ah, like a 12B4 or 6AS7/6080? Only those are square bent, not U.

Tim

--
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