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Tom Schlangen
 
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Default EL83/6CK6, PL83/15A6

No, not another dreaded plate curve sheet from me ;-)

Instead, get this Marconi PL83 data sheet from Frank
Philipse's site:

http://frank.pocnet.net/sheets/126/n/N309.pdf

As I see it, this noval based pentode intended for
video outputs is very linear in pentode mode and
when being triode strapped, too. See the Marconi
sheet, page 8, for the trioded data.

Moreover, the 300mA heater versions PL83/15A6 are plenty
and cheap as dirt at least here in Germany. Might be
very worthwhile to invest a few cents in that tube
and an LM317 for the heater CCS and have a try at it :-)

Tom

--
this is my favourite sig, since there is no reference to
Kibo, Discordianism or The Church of the Subgenius in it.
  #2   Report Post  
Ian Iveson
 
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Default

"Tom Schlangen" wrote
...
As I see it, this noval based pentode intended for
video outputs is very linear in pentode mode and
when being triode strapped, too. See the Marconi
sheet, page 8, for the trioded data.

Moreover, the 300mA heater versions PL83/15A6 are plenty
and cheap as dirt at least here in Germany. Might be
very worthwhile to invest a few cents in that tube
and an LM317 for the heater CCS and have a try at it :-)


Similar to 6CH6 (EL821), but less perveant, if that's a word. OTOH
300mA is heaps more convenient than 750mA. Heater power is greater
than output power in class A for 6CH6, although that's a common
complaint I suppose.

One feature of these valves is the gentle rise in current from Vak=0
for any particular Vgk. with no clear knee. Since screen curve is
mirror of anode curve, this means that screen current can become a
problem at higher values of Vak than with the common audio beam
tetrodes.

So not so suitable for CFB designs, particularly if you want
super-pentode (where Vsk is kept constant). The power advantage of
CFB is in utilising that low Vak region. Combination of high gain
and reasonable distortion otherwise make them good candidates.

I notice 6CH6 prices are rising. I should have got more...I think
they are generally of good quality.

cheers, Ian


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Ruud Broens
 
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Default


"Tom Schlangen" wrote in message
...
: No, not another dreaded plate curve sheet from me ;-)
:
: Instead, get this Marconi PL83 data sheet from Frank
: Philipse's site:
:
: http://frank.pocnet.net/sheets/126/n/N309.pdf
:
: As I see it, this noval based pentode intended for
: video outputs is very linear in pentode mode and
: when being triode strapped, too. See the Marconi
: sheet, page 8, for the trioded data.
:
: Moreover, the 300mA heater versions PL83/15A6 are plenty
: and cheap as dirt at least here in Germany. Might be
: very worthwhile to invest a few cents in that tube
: and an LM317 for the heater CCS and have a try at it :-)
:
: Tom
:
: --
: this is my favourite sig, since there is no reference to
: Kibo, Discordianism or The Church of the Subgenius in it.

Not bad, but some 3rd harmonic distortion to be expected, as the
spacing between the different curves 'wobbles'.
Want a really linear trioded tube ? EL 90, by Lorentz,
almost too good to believe :-)

cheers and thanks yet again for posting some measurements (ECL84..:-)
Rudy


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Ruud Broens
 
Posts: n/a
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"Ruud Broens" wrote in message
...
:
: "Tom Schlangen" wrote in message
: ...
: : No, not another dreaded plate curve sheet from me ;-)
: :
: : Instead, get this Marconi PL83 data sheet from Frank
: : Philipse's site:
: :
: : http://frank.pocnet.net/sheets/126/n/N309.pdf
: :
: : As I see it, this noval based pentode intended for
: : video outputs is very linear in pentode mode and
: : when being triode strapped, too. See the Marconi
: : sheet, page 8, for the trioded data.
: :
: : Moreover, the 300mA heater versions PL83/15A6 are plenty
: : and cheap as dirt at least here in Germany. Might be
: : very worthwhile to invest a few cents in that tube
: : and an LM317 for the heater CCS and have a try at it :-)
: :
: : Tom
: :
: : --
: : this is my favourite sig, since there is no reference to
: : Kibo, Discordianism or The Church of the Subgenius in it.
:
: Not bad, but some 3rd harmonic distortion to be expected, as the
: spacing between the different curves 'wobbles'.
: Want a really linear trioded tube ? EL 90, by Lorentz,
: almost too good to believe :-)
:
: cheers and thanks yet again for posting some measurements (ECL84..:-)
: Rudy
:
ehh, Lorenz. Here are some numbers:
penthode, PP, 9W @ 2.5 % THD
trioded, PP, 1.7 W @ 0.4 % THD

breakdown pent., Raa=10 k 5.5 W 1% 3rd H, 0.3 % 2nd
trioded, Raa= 4 k 1 W 0.11 % 3rd H, 0.22 % 2nd ; 0.02 % 3rd @ 400 mW

not bad, eh :-)
Rudy
(a headphone amp design, anyone ?


  #5   Report Post  
Ruud Broens
 
Posts: n/a
Default


: : Want a really linear trioded tube ? EL 90, by Lorentz,
: : almost too good to believe :-)
: :
: : cheers and thanks yet again for posting some measurements (ECL84..:-)
: : Rudy
: :
: ehh, Lorenz. Here are some numbers:
: penthode, PP, 9W @ 2.5 % THD
: trioded, PP, 1.7 W @ 0.4 % THD
:
: breakdown pent., Raa=10 k 5.5 W 1% 3rd H, 0.3 % 2nd
: trioded, Raa= 4 k 1 W 0.11 % 3rd H, 0.22 % 2nd ; 0.02 % 3rd @ 400
mW
:
: not bad, eh :-)
: Rudy
: (a headphone amp design, anyone ?
:

...the RCA 9002 !!

Just below max. recommended dissipation, at 1.5 W,
this tube, at Vg1k -6 V, about 7 mA @ Vak 225 V,
just doesn't seem to distort at all (ok, little exxagg.
when loaded with about 50 K - obviously, impractical with a resistor,
but with an active circuit on top...

linear greetings,
Rudy


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