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Re: Bert Hickman

Robert,

Thanks for the complements!! The main reason I chose to seperate the
caps and gaps from the primary had to do with the height of the homemade
capacitors and the clearance height above the coil. Because of their
construction, the capacitors are about 19" high, the coil stands about
44" high, and my floor-to-beam height is about 96". There was no was I
could mount the caps underneath the coil and still have adequate
vertical clearance for the toroid. As it is, the coil is sitting on top
of only an 8" high (would prefer 24+") LDPE container so that I can get
44" of clearance above the toroid. 

I initially had the capacitor and gaps closer to my 6" coil. As I
increased the power level, these became increasingly favorable targets
for secondary hits, and were disturbing the E-field around the toroid.
In the pictures on the ftp site, the primary lines were a mix of 1/0
welding cable and 1" x 1/8" tinned copper braid inside 1/8" vinyl
tubing, since I had scraps of these on hand. Now, thanks to Joe Cassata
of the Coax Connection (who lives only about 5 miles from me!), I've
gone to a pair of 15 foot long #2 AWG Teflon insulated, silver plated
flexible cables, also inside 1/8" vinyl tubing. These are dressed in
parallel to reduce the amount of of-axis inductance. I have noticed no
change in coil behavior or performance. BTW, this cable was originally
custome made for Uncle Sam, and ran me about $1/foot - Joe's got more if
anyone needs some. I guarantee that "Uncle" paid a lot more for it!

You are correct: I am throwing away some energy in this configuration.
By going to paralleled cables, most of the off-axis inductance should
cancel. The skin-effect and resistive losses are still there, and
probably account for as much as 1/2 of the total primary circuit
"effective" resistance (not including the gap). Corona losses are also
probably present, but I don't see any visible corona, and I would guess
that these are relatively small. When the gap starts firing, most of the
losses still show up in the arc. I've measured the primary Q with no
secondary with a storage scope and a pickup antenna, using the cycle
counting to 10% decrement method. The measured primary Q without the gap
is about 70, and with the gap is about 10-11. I have a suspicion that,
given the lossiness of the gap, the added cable length in my
configuration is probably not causing any large loss of system
performance. It certainly is not optimal, however....

Down the road, I will probably migrate to commercial caps, which should
permit mounting them and the gap closer to the primary. Thanks for your
input - It's nice to get solid feedback from one of the more experienced
high power coilers on the net!

Safe coilin' to ya!

-- Bert --


Tesla List wrote:
> 
> >From rwstephens-at-ptbo.igs-dot-netWed Sep 25 22:07:06 1996
> Date: Wed, 25 Sep 1996 19:49:18 -0500
> From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Bert Hickman
> 
> Bert,
> 
> I thought your post on the light bulb experiment was very good.
> You've dared to guestimate how much current is available in the
> output streamer by looking at it as an isolated capacitance.  I think
> you are probably right to consider it this way.
> 
> I got a chance to view your coil photos at nic.funet.fi.  They look
> great!  Nice to put a face to the person often active on the list.
> >From the pics I can tell that you are somewhat of a perfectionist who
> takes pride in his work, it shows : ).  You look like the kind of guy
> that would not release a photo of an aluminum flex duct based toroid
> on your coil, or perhaps even use it in public, if it has been dropped or
> slightly dented.  I am of the same breed.  (Now before you others get
> on my case, my coils are relatively pretty, my shop looks like a
> disaster!).
> 
> I seem to decode from your pics that you have remoted your system
> capacitor and break via heavy high voltage cables to the primary coil
> with a third cable for strike ring and secondary ground.  Do I see
> this as it is?  If so.  WHY?  You are throwing away energy.  In a
> tandem setup operating from a common oscillator you must do this, and
> when this is done it is practice I've seen to use elevated parallel copper
> water pipe as balanced RF transmission line, an attempt to reduce
> unavoidable losses.  In your pictures, if I am seeing this setup
> correctly, your tank circuit leads are draped across the floor.  If I
> am in error here, please tell me to go mind my own #-at-%*% business.  If I am
> correct, let's chat.
> 
> Here's a good subject for another thread guys!
> 
> regards,
> 
> rwstephens