Re: 811 tube coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 7/1/02 7:08:04 PM Eastern Daylight Time, tesla-at-pupman-dot-com
writes:

Steve,

If the tube plate is not red, then it's probably running within safe current
limits.  A barely perceptible red color is acceptable for intermittent use.
811A's are rather wimpy tubes, so you'll never get very long sparks,
although I think some folks get a little more than 2.75".  It may help
to sharpen the breakout point to a very sharp point to help the coil
to break out.  Some doorknob caps are very good, others are very
bad.  You'd have to have the correct type.  An MMC cap should be
OK, since many folks have used them with good results in tube coils.
It sounds like your tuning is OK, but it's difficult for me to be sure
from here.

Cheers,
John


>
> Hi,
>
> I have a question that somewhat relates to the post but just a general 
> question about operation.  Sometimes when tuning, i cannot get any sparks to 
> breakout, unless i bring a screwdriver very close.  When this happens, the 
> Amp meter says its pulling 6A which means that the tube is running at its 
> max.  Is this dangerous to the tube?  I try to prevent this as much as i can 
> but it seemed to happen alot today.  Also a very opposite situation is that 
> ive managed(or so i think) to achieve the best tuning with my tuning cap.  I 
> get current draw of less than 3A, and i get a good 2.75" arc.  Does this 
> sound like im getting close to having the best tuning with my current cap?  
> Im also wondering about my cap, it gets very warm(actually hot).  Its a 
> small MMC of poly caps.  Total for the bank is 900pf at 8kv.  Im supposed to 
> have a 1000pf cap at 10kv, its also supposed to be doorknob type.  Would a 
> doorknob really work any better?  If so, where could i get one.  I want one 
> of the best caps i can get(for cheap) because my performance seems to be 
> highly relying upon this cap.
>
> Steve Ward.
>