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Re: 813 VTTC Problems

Original poster: "Mike" <mikev@xxxxxxxxxxxxxxxx>

HI Chris,
                Mike here, usually reply from induction@xxxxxxxxxxx and I
direct emailed you prints to that tube.
G3 goes to the Center Tap of your filament transformer, also your system DC
ground. If you are using a DC power supply on the filament for low hum (not
likely) then it would go to the negative terminal of that DC filament
supply.
I don't know if you are trying to run that triode connected or if you plan
to use the screen grids.
At any rate, NEVER run HV to the screen without  drop resistor  if you are
using plate supply  to feed screens  as well as the plate and always make
sure you have HV on the plate of the tube when you are placing screen
voltage there. Else the screen is the most positive and will try and act as
the plate, which it is not power rated to do.
The plate should take the current.
The screen, if desired, will pull a small current if you DC connect it that
way. Pick the drop R based on plate volts and rated screen volts.
If you are trying to triode connect, tie G1 and G2 together, with G3
connected to the CT of filament transformer.
Just takes more to drive it, also need grid leak and if you wish, fixed
bias.
I don't have the print you are working from.
Regards,
Mike



----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, August 29, 2005 3:32 PM
Subject: 813 VTTC Problems


> Original poster: "Chris Fanjoy" <zappyman@xxxxxxxxxxx>
>
>    Still trying to get this dual 813 VTTC going, with no luck. The
> main problem right now is figuring out what to do with the extra
> grids (G2 and G3) of the 813 tubes. I didn't have anything to go by,
> so I connected both G2's together and connected them to the 4KVDC
> supply via a large 10kohm resistor, and left the G3's unused. The
> resistor violently exploded the instant power was applied. It's my
> understanding that the G2 of a tube isn't supposed to draw any
> current - so something must be wrong somewhere! I'm suspecting that
> one or both of the tubes may be bad; I'll be doing more tests but
> this time with a Variac, to confirm if this is the case or not.
>    How exactly should the G2 and G3 grids of these tubes be connected
> to the circuit? And are they actually supposed to draw current?
>    Thanks for any advice.
>
>
>