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[TCML] Re: VTTC schematic for 813

Hi Mike,

I had some time after work to look at the data sheets for this tube.

I want to correct a few things I posted. First, I had a typo in an earlier
message... should be "characteristics". Oops :-P

Second, the beam forming connection, which is noted as grid no. 3 on a
couple of different data sheets I looked at, is hooked up to mid-tap of the
filament transformer secondary winding or to the negative end of the
filament when operated on DC filament supply.

Chris Reeland
Ladd Illinois USA

Sent from my Samsung Galaxy Tab® S

On Mon, Sep 20, 2021, 1:16 PM Chris Reeland <chrisreeland@xxxxxxxxx> wrote:

> Hi Mike,
> I want to add to John's reply.
> The screen connection of this tube also can be utilized with a separate
> dedicated power supply.
> Also going from memory of this 813 tube, there is also a beam forming
> connection there, which again would be best utilized by a separate
> dedicated power supply if I am correct here.
> That said, me personally, I would not be trying to use this type of tube
> on a VTTC.
> Unless you have something else in mind for this VTTC besides "sparks" in
> addition to?
> I would try to stick to simple triode tubes.
> Chris Reeland
> Ladd Illinois USA
> Sent from my LG V20
> On Sun, Sep 19, 2021, 11:01 PM Futuret <futuret@xxxxxxx> wrote:
>> Mike,
>> I had built a VTTC some time ago in which I experimented with
>> using various tubes such as the 810, HF300, and also an 813.  the 810 or
>> the HF300 produced a 21" spark output.  the 813 gave a 16" spark.  I tried
>> it with the control grid tied to the other grid.  I also tried it with the
>> other grid fed through a dropping resister from the HV power transformer.
>>  It gave 16" in both cases.  My guess it that with further optimization it
>> would probably have given a 21" spark like the other tubes.  Although these
>> tubes were probably rated for around 2 or 3 thousand volts DC on the plate,
>> I fed them with around 3200 volts AC on the plate.  The schematic was just
>> the basic type VTTC schematic which is very commonly used.  I also used a
>> 140V output step up type variac to power the VTTC.
>> John
>> On Thu, Sep 16, 2021, 10:09 PM MIke Widlar <mike@xxxxxxxxxx> wrote:
>> > I'm new to this forum.  I currently looking to see if anyone has a
>> > schematic
>> > for a VTTC using a single 813 power tube.  I had this working
>> previously,
>> > but I could only pull a 2" spark off it.  I pulled the setup apart and
>> > packed everything up.  Now I'm ready to put all the pieces back together
>> > again and get something going.  I have also secured a 2500 DCV plate
>> source
>> > which I can draw at least 400ma.
>> >
>> > If someone could provide some guidance it would be greatly appreciated.
>> >
>> > Regards,
>> >
>> > Mike
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