Re: [TCML] New 833C VTTC - poor performance

[futuret@xxxxxxx]

Kris,



You're doing all the right types of adjustments.? I assume

you have a breakout point above the toroid (about 4 to 5" tall

or so maybe).?? Steve's coil is a good design.? It should work

well and give at least 22" sparks.? The tuning is quite critical

and all the adjustments are critical sometimes.? Here's what

the problem might be.? You have to tune at full power.? If

you tune at low power, the tune point will be wrong at high

power.? So you have to gradually work your way up to the 

longer sparks, retuning and re-adjusting everything as you

increase the power and get longer sparks.? In other words.

Let's say the tube gets red at 8" sparks, then re-adjust so

it doesn't get red, but then it may get red at 10" sparks,

then re-adjust again, etc.? Takes awhile sometimes to

get a tube coil running right.? I assume your caps can

handle the power?? Are they getting hot??? Here's another
possibility.? Did you verify that the tube pins are getting
10V while the filament is lit?? If the filament transformer
gives 10V with no load (not connected to the tube), then 
it might only give 8 or 9 volts under a load (connected
to the filament.? I assume you checked all this but
I figured I'd mention it.? It can take a long time to get
a tube coil tuned up compared to a spark gap coil. 

Also if you have an 833A, you can try that.? It will show
a red plate much sooner than the 833C, which can actually
make it easier to tune the coil.? An 833C should not get red
until the spark is over 22" or so.? You can try using a higher
grid resistance too.? Just put another resistor in series
with the one you have.? But the value you're using should
be OK anyway I think.? 

Cheers,
John


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