12E1 question
Thomas Suhadhi
I just bought STC/ITT 12E1 tube.
It was a pentode output tube with the same pin out with KT88.
The only parameter I know about this tube was Va max = 800V.
So I put it in the output of pp amplifier circuit with Va = 500V.
Fisrt I set the bias pot to minimum, but the tubes immediately goes to
cherry red.
Anybody have an experience with this tube or suggestion to make it work
properly?
Thank's in advance for any and all replies to this message.
Cheers,
Thomas Suhadhi.
Chris Morriss
In article <336F05...@cbn.net.id>, Thomas Suhadhi
<tri...@cbn.net.id> writes
They are closer to a 6550 than a KT88. Because of their higher
transconductance they require a much HIGHER (more negative) bias than a
KT88. If you're trying to run them at a very high anode voltage you'll
never get them to be linear. (and they'll need a lot of bias to keep
the anode current down to a resonable level)
--
Chris Morriss
Ned Carlson
Thomas Suhadhi <tri...@cbn.net.id> wrote:
>I just bought STC/ITT 12E1 tube.
>It was a pentode output tube with the same pin out with KT88.
>The only parameter I know about this tube was Va max = 800V.
>
>So I put it in the output of pp amplifier circuit with Va = 500V.
>Fisrt I set the bias pot to minimum, but the tubes immediately goes to
>cherry red.
>
>Anybody have an experience with this tube or suggestion to make it work
>properly?
>
>Thank's in advance for any and all replies to this message.
>
>Cheers,
>Thomas Suhadhi.
>
You either need to (a) wire in triode, or (b) cut the screen (g2)
voltage a bunch (possibly a low as 150V). My limited data
says that for Va 150V, Vg2 150V and Vg1 -9V, these puppies
draw Ia 200 ma!
I've seen these successfully used in triode mode at up to Va 450V,
they might work that way at 500V, but you'll probably have to change
bias-supply resistors for more negative bias voltage.
BTW, were is .id, anyway? Iceland? Just curious.
Ned
David Crittle
Thomas Suhadhi wrote:
>
> I just bought STC/ITT 12E1 tube.
> It was a pentode output tube with the same pin out with KT88.
> The only parameter I know about this tube was Va max = 800V.
>
> So I put it in the output of pp amplifier circuit with Va = 500V.
> Fisrt I set the bias pot to minimum, but the tubes immediately goes to
> cherry red.
>
> Anybody have an experience with this tube or suggestion to make it work
> properly?
>
> Thank's in advance for any and all replies to this message.
>
Dear Thomas
check the pinouts! You say they have the same pinouts, but this is not
possible because type 12E1 has as top cap anode, whereas KT88 does
not.
Sander de Waal
Thomas Suhadhi wrote:
> I just bought STC/ITT 12E1 tube.
> It was a pentode output tube with the same pin out with KT88.
> The only parameter I know about this tube was Va max = 800V.
> BUT: G2 voltage should be <300 Volts!!
> So I put it in the output of pp amplifier circuit with Va = 500V.
> Fisrt I set the bias pot to minimum, but the tubes immediately goes
> to
> cherry red.
> Imax G2=12 mA..So put in a resistor or lower supply voltage.
>
> Anybody have an experience with this tube or suggestion to make it
> work
> properly?
> For the rest, this tube operates with nominal Vg2 = 150 volts...
So with high anodevoltage, find another supply point for g2, UL-
operation won't be possible here...This is NOT equal to KT88!!!
>
> Thank's in advance for any and all replies to this message.
>
> Cheers,
> Thomas Suhadhi.
Best regards, Sander de Waal
--
MZ
Claude Frantz
Thomas Suhadhi <tri...@cbn.net.id> writes:
>I just bought STC/ITT 12E1 tube.
>It was a pentode output tube with the same pin out with KT88.
>The only parameter I know about this tube was Va max = 800V.
>So I put it in the output of pp amplifier circuit with Va = 500V.
>Fisrt I set the bias pot to minimum, but the tubes immediately goes to
>cherry red.
>Anybody have an experience with this tube or suggestion to make it work
>properly?
It is an electrometer tube, i.e. a low level tube. You cannot use it
as a substitute for a power tube. Now, it has probably become useless
because of the severe overload.
--
Claude
(cla...@bauv106.bauv.unibw-muenchen.de)
The opinions expressed above represent those of the writer
and not necessarily those of her employer.
Herbert Rotscheidt
cla...@bauv.unibw-muenchen.de (Claude Frantz) wrote:
>>> Thomas Suhadhi <tri...@cbn.net.id> writes:
>>>
>>> >I just bought STC/ITT 12E1 tube.
>>> >It was a pentode output tube with the same pin out with KT88.
>>> >The only parameter I know about this tube was Va max = 800V.
>>>
>>> >So I put it in the output of pp amplifier circuit with Va = 500V.
>>> >Fisrt I set the bias pot to minimum, but the tubes immediately goes to
>>> >cherry red.
>>>
>>> >Anybody have an experience with this tube or suggestion to make it work
>>> >properly?
>>>
>>> It is an electrometer tube, i.e. a low level tube. You cannot use it
>>> as a substitute for a power tube. Now, it has probably become useless
>>> because of the severe overload.
as far as i can see the original poster is correct. the 12E1 is
indeed a power-pentode with the same pinout as the KT-88, except
for the anode which goes to a cap at the 12E1's top. electrometer
tubes usually have a rather small heater (the 12E1 burns up 10 W,
same as the KT-88) and are to measure extremely low grid-currents,
typically of the order of 10^-10 amps. the max. plate-dissipation
is 35 W. i've never crossed any electrometer tubes which looked
like a 12E1...
if you haven't produced cherrys for long i don't believe this has
ruined your 12E1. haven't got detailed data for it; it may be
that it requires (esp. in PP-mode) a more negative Vg1 than you
can get by tweaking this pot. the 12E1 can stand even a higher
max. Ip than the KT-88 but its normal operating voltages seem to
be lower (although Vpmax = 800 V as you said).
if this problem doesn't originate from a faulty amp you could try
moving the point of operation into another region which is better
suited for the 12E1, by playing with Vp, Vg1 and Vg2 if possible.
for a start perhaps you measure the maximum obtainable bias voltage
(without inserting the 12E1)...
good luck -
Herbert
Claude Frantz
cla...@bauv.unibw-muenchen.de (Claude Frantz) writes:
>It is an electrometer tube, i.e. a low level tube. You cannot use it
>as a substitute for a power tube. Now, it has probably become useless
>because of the severe overload.
I'm very sorry, this information is wrong. There was a confusion.
The data of the 12E1 is here:
Heater: 6.3 V at 1.6 A
Typical: Va = Vg2 = 150 V, Vg1 = -9 V, Ia = 200 mA, Ig2 = 12 mA
S = 14 ma/V
Maximum: Va = 800 V, Vg2 = 300 V, Vg1= -100 V, Ik = 300 mA, Wg2 = 5 W,
Wa = 35 W.
I'm very sorry for the mistake.