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Six inch coil & SRSG

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

Well, I finally got my six inch coil set up and tested last night with the 
new synchronous rotary spark gap.  Primary cap is .050 ufd, 5 kva 14.4 kv 
pole pig balasted with a 5,000 w Luxtrol dimmer variac with a 1,000 w 1.6 ohm 
resistor in series.  It runs very good, massive sparks everywhere, even 
hitting the cement driveway.  John, the phase control system works great.  I 
wouldn't even like to run this coil without it.  I found the 240 bps position 
on the phase control variac and also found the 120 bps position.  At 240 bps, 
there is an intense blue corona field that forms from the top of the coil to 
the outside of the primary, looks like a Christmas tree.  At 120 bps, this 
field is more intense and I was afraid to run it very long here because I did 
not want to destroy the secondary like I did on my small 3" coil when testing 
this spark gap.  The bottom turn of the secondary is just about even with the 
flat primary.  I will need to reduce the coupling and try it again at 120 
bps.  I really did not see any difference in spark output at 120 vs 240.
Bill Wysock, the rotary works great, thanks for your work.

I tried shorting out the 1.6 ohm ballast resistor and the spark gap starts 
popping and the system runs very rough.  It did not like that.  I was able to 
get up to 30 amps primary current into the pig at just over 250 volts - 
should be about 7.5 kva.  Even blew the 30 A breakers down stairs for the 
first time. Max spark length was the same as with the async rotary gap which 
is 104".  Has anyone beat this length with a 6" secondary?

After getting some experience, it was easy to find the 120 and 240 bps 
points.  You can tell by the tone and by feeling the rotary contacts after a 
run.  At 120 bps, only two of the four contacts get hot.  At 240 bps, all 
four get hot.  After about a two minute run, the contacts are very hot.  Hot 
enough to burn your fingers.  I do have an additional cooling fan mounted on 
the box that covers the rotary.  I had my safety gaps across the rotary set 
at .45" and they never did fire.

All in all, lots of fun, it has been quite a while since I have run this coil 
at full power.

Ed Sonderman