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RE: ^^(my) First Light ^^
Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>
Your coil is much like mine a few rev's ago. Mine used a 15/60 NST,
identical primary and secondary, same Fair Radio Sales cap, 4.5"x15.5"
toroid, and a 10-segment RQ/TCBOR cylinder gap w/ 0.30 total gap and
fan-cooling. Performance was 43" streamers.
More comments following your questions below:
>Original poster: "Matt S. by way of Terry Fritz <twftesla-at-qwest-dot-net>"
>(questions at end :-) )
>So, .... I finally got my coil to a point where I could consider firing
>up. I set it up on the porch, and realized that my (manly) hookup
>was too large for the connectors I had on hand.
>With my wife and kids already (sort of) anticipating the event, (even
>I told them I had a low confidence level of success), I decided to hook
>the tank components with ... ..... those little Radio Shack alligator
>leads.... no PVC tubing.
>My coil specs:
>4.25" secondary, 22 ga, 23.375 inch winding length.
>6.26" id primary, .25 tubing, .5" spacing, 15 deg inv. cone
>strike rail 22" dia, 2" up from last turn of primary
>toroid 4" ducting, 17" total dia.
>multi segment static gap (~.2" total spacing)
>rf ground = 20 feet of #2? welding cable to an 8 ft (well watered)
>and, temporarily, since I didn't get my MMC done, .. a trusty old fair
>.01 uf 100kv cap
>Anyway, .. it was just getting dark, ... I set the safety gaps, ...
>it up, taped a wad of aluminum (aluminium) foil to the toroid.. and ran
>20-30 volts from the variac.
>the gap started making noise...
>My 16 yr old son said "Dad, there's something coming out the top".
>I was preparing to give him a speech on the power of suggestion when I
>noticed a bunch of 4" "streamers" coming off the foil.
>So I yanked off the foil and gradually increased the input voltage to ~
>.. and...the safety gap fired and wouldn't stop....
>So, .. I opened the s.g. up, .. and did it again, and the same thing
>happened, ... so I started to open it up again and I heard Terry's
>voice in a past post in my head saying "whatever you do, don't open the
>after setting it (if you want your NST)" (paraphrasing).... .. (s.g.
>to just not fire with nothing connected).
>After getting a grip, .. I decided to (lose that grip and) just crank
>variac further (family pressure and all)... and the safety gap (mostly)
>stopped firing, and there were hundreds (I think) of 10 inch streamers
>swirling around the toroid....
>and then at120 volts in, and 4 to 6 simultaneous 24" streamers along
>bunch of smaller ones at the same time.
>All this in a pretty strong breeze.
>This breaks a life-long record of never getting anything of any kind
>on the first (10) attempt(s).
>I just picked a tap point on the primary during setup (~7 turns)... and
>luck had it, .. it was pretty close.... when I moved it from there, the
>streamers decreased (although I was going a turn at a time).
>No doubt I am feeling chipper about it all, .. assuming that I can get
>much better with cap/gap/top/K/tuning adjustments.
>Not to mention proper wiring.
>Eventually (after 10 minutes on and off-- mostly on) one of the R.
>mini-jumpers blew a hole in it and started a cooking arc across my
>finished primary base, .. but it's a battle scar I can live with.
>For the record, the F.R. cap did get a little warm.
>And the output decreased considerably after running for a min. or so
>assuming due to the gap having no fan.
>So, ... just in case anyone read this far I wanted to say thanks to the
>list... .. no way I could have tortured those multi-colored jumper
>without all the help and archives and answers to my dumb questions.
>Which I have a few more of :-)
>1. Any ideas on what happened that allowed my wildly firing safety gap
>stop firing by cranking up the voltage more?
A hot gap will fire at a lower voltage. Also, at a higher input
voltage, the gap will fire more frequently, and I believe that with less
time between firings, more hot and ionized gasses persist between the
gaps (especially without a fan), again resulting in a lower firing
>2. I know I've read this somewhere, but when the S. gap fires a lot, is
>tuning or over coupling?
Tuning. Overcoupling results in sparks running along the surface of
>3. I'm assuming from the many streamers that my topload is too small?
Yes. And the experience of most coilers is that a bigger topload is
always better, as long as a breakout is possible.
>4. 22 gage wiring from the cap to gap to primary and it worked? what
Losses will be higher in such thin wire, but it remains to be seen how
large an impact on actual performance this will have.
>5. In addition to a "Power on LED" I put a silly little green LED on my
>control cab. in parallel with the voltage meter.. .. thought it would
>me some reference point in the dark. .. it lights at 70 volts. With
>coil running, it would flicker at much lower input voltage to the
>I have two corcom filters in between, but does this mean some V spikes
>coming back, or does a variac output voltage fluctuate a little when
You got me there. What kind of LED is used for 120VAC monitoring?
>Thanks again for all the help. I have never seen a coil run before ..
>.. well. .. there's nothing I've seen that comes close. (and my wife
>it and temporarily forgot about all the $$ and time spent on it)(and my
>made the same sounds that they do when watching fireworks)(ok, and my
>who was confined inside, had a spaz attack and tried to dig a hole in
>hardwood floor to hid in, but 3 out of 4).
I suspect that outdoor breezes have a big impact on performance. Also,
if your pri-sec coupling is too small it could also reduce performance.
Regards, Gary Lau