Re: [TCML] Tuning Questions

[cbroring@xxxxxxx]

John

Thanks for the reply and I enjoyed reading the "Efficiency Theory" 
section of your web page.  I ran my coil through JAVATC, which I 
probably should have done before I built it,  and the model says my 
coupling was in fact too low.   I modified the primary with state of 
the art Popsicle stick and glue gun technology to make it adjustable in 
height.  I adjusted the coupling even tighter and found no further gain 
in streamer length but did find tuning to be much less critical, so I 
left it that way.   This is very much like tuning my ham radio 
transmitters and antenna couplers.

Streamer length is greater then 14 inches which is a lot less then 
JAVATC suggests.  However from what I read, an OBIT may pass less power 
then it's rating suggests.  Any comments on this performance from a 
single OBIT and salt water bucket capacitor?

I have another OBIT on the way to add in parallel whit the one I have.  
I also dug out an old 6000 volt ct. 1kva+  radio plate transformer that 
I may try.   I'm a bit concerned about  the relatively low voltage of 
this plate transformer.  I thought the low voltage/ higher current of 
such a supply may also necessitate making another big messy bucket 
capacitor.   Any comments on using this bigger transformer are very 
welcome.

Charlie

-----Original Message-----
From: futuret@xxxxxxx
To: tesla@xxxxxxxxxx
Sent: Sun, Feb 14, 2010 10:00 am
Subject: Re: [TCML] Tuning Questions



Charlie,

Maybe the coupling wasn't all that tight to begin with?  It's true 
though
that a lower powered coil of a given size can tolerate a tighter 
coupling
than a higher powered coil of that same physical size (assuming
the same break rate).  Surely you'll get longer sparks if you parallel
another OBIT, but the coil may still benefit from tighter coupling,
after that.  It's difficult to say for sure in advance.  If you add 
another
OBIT and leave the spark gap spacing unchanged, the break rate will
increase, so the bang size may stay the same.  With an extra
OBIT, you may need a fan blowing on the spark gap for cooling
(if you're not already using a fan).

I usually make my secondary coil adjustable in height.  First I lower
the secondary until l get racing sparks, then I raise it until they 
stop.

 http://futuret.110mb.com

Cheers,
John








-----Original Message-----
From: cbroring@xxxxxxx
To: tesla@xxxxxxxxxx
Sent: Sat, Feb 13, 2010 9:42 pm
Subject: Re: [TCML] Tuning Questions


Matt,

Thank you very much for replying to my questions.

This evening I added the "off axis tuning" inductor and beefed up all 
the
connections in the primary.   As probably everybody else knows chasing 
the
optimum primary tuning is a bit like shooting at a moving target 
because the
secondary tuning changes when streamers or arcs develop.  Anyway, I 
didn't find
much improvement here.

I tried a nice tidy "professional looking"  nail break out point on the 
top load
toroid and it it doesn't work as well as the previous screwdriver 
hanging over
the edge of the toroid.

Then I had a Eureka moment.  I raised the primary 1.5 inches and the 
coil really
woke up.  I guess it needed tighter coupling.  I need to redesign the 
primary
and try even more coupling.  So, I have another question for those more
experienced coil builders.  Is the need for close coupling a common
characteristic of an under powered coil such as mine?  If I parallel a 
second
OBIT will the extra available driving current lessen the need to 
tightly couple
the primary and secondary?

Thanks

Charlie
K3YA




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