[Prev][Next][Index][Thread]

Last weekend report...

Quoting Chip 

> The first question is this:  We had an air blast gap (only) and
> a pole pig for power.  As I turned up the power, I noticed that
> the output peaked before the full throttle setting.  This seems
> a little counter intuitive -- I thought that as I turned up the
> juice that the sparks would get louder, longer, and fatter.  
> Instead, they actually got smaller, quieter and maybe even 
> thinner.  Has anyone had this happen? 

> As I think about it, perhaps the spark gap was getting
> overwhelmed and not quenching, but arcing more. Any comments or
> suggestions?  I don't yet have the rotary gap made, so that's 
> why I wasn't using one. 

This is a textbook example of reaching the peak, then exceeding,
the power handling ability of the gap. The more voltage applied,
the more the gap shorts outs, the less power that is switched
into the tank circuit.

> The second question:  With the pole pig, the sparks were _much_
> louder, but not much longer (20" max).  Is the noise from the 
> greater input power, while the lack of length is due to the 
> lack of adequate quenching?  Another thing this could be is a 
> symptom of my ground getting overwhelmed.  Currently the ground
> is an 8' piece of 1" Cu pipe connected by (yes, I know) braided
> strap ~1/2" wide and about 15' long.

Nahh, this is a gap problem. When the ground path backs up and
is overwhelmed the coil output does not decrease, added power
simply does not result in any increase. On the other hand, poor
gap performance will result in decreased output with increased
power input.

Sounds like a good test. You certainly proved the limits of the
static gap on externally current limited transformers.

Richard Quick


... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12