Re: VTTC Operation and Filament Warm-up

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Original poster: "Steven Ward by way of Terry Fritz <teslalist-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

Hi,

I am definately no expert about tubes.  But with my 833A coil, i usually 
give the fils at least 15 seconds to heat up.  And with this power up surge 
idea being mentioned, i took an extra step and added a 25 ohm 25 watt power 
resistor on the 120V side of my 10v 20A transformer.  I added a little 
switch to bypass the resistor.  With the resistance, there is no surge, and 
the fils glow at about 1/2 brightness.  I let that go for a few seconds, 
then flip the bypass switch, and now were at full brightness :)  I did 
actually hear a large surge sometimes with these tubes upon turning the 
filament supply on.  Now, everything is quiet and smooth.  Also note that 
25watts for this resistor is terribly underrated!  So the warmup can only 
be about 5 seconds at most, before that resistor is sizzling hot!  But it 
works fine now, so it works for me.  It may be wiser to use a 100watt 
resistor if you want a prolonged warmup time (i cant see why though).  I 
wish i would have done this with the 304TL's :(

Steve Ward.