RE: Please Help! Trying to tune the primary coil (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 24 Dec 2006 13:20:15 -0800
From: Jim Mora <jmora@xxxxxxxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE: Please Help!  Trying to tune the primary coil (fwd)

Hi DC,

I would be interested in you schematics. I noticed in Baraboo you were using
a tiny spark gap while adjusting for maximum power out. I didn't get a
chance to ask you how that worked.

Also, I am planning a 15 degree primary again on my 12" coil. How do you
adjust the secondary height or is that depicted a fixed end cap?

I managed to adjust my res freq pretty easy on my 8" coil but I would think
this should be done with all the components in place as it will be when lit
up.

Thanks,
Jim Mora

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx] 
Sent: Sunday, December 24, 2006 8:29 AM
To: tesla@xxxxxxxxxx
Subject: Re: Please Help! Trying to tune the primary coil (fwd)

Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 24 Dec 2006 09:13:34 -0700
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Please Help!  Trying to tune the primary coil (fwd)




I've sent the schematic to him off-list.  I also sent some schematics for 
dynamic Q measurement of sec coil, measuring coeff. of coupling with a tank 
heater, and a small Tesla coil tuning indicator (used with coil live 
sparking) that we use for dynamic coil tuning.

If anyone wants these sketches contact me off-list and I will email them to 
you.

Dr. Resonance



>
> I've gotten to the stage where I need to tune my primary tap point, and
> I've run into a problem in trying to figure out how to wire up the
> primary coil to find the resonant frequency.    I initially pulled the
> secondary, put it on a plastic base, injected RF from my signal
> generator, and read the response off of my oscilloscope with a small
> antenna set as the input feed.  This worked well, and gave me a resonant
> frequency of 205KHz for a 4" x 22" coil with a 5x16 toroid topload.
> Here are pictures of the setup (sorry for the fuzzy initial picture)
>
> Secondary tuning setup Antenna: 
> http://www.flickr.com/photos/51115445@N00/331719458/
>
> Secondary base (so it doesn't fall over when measuring): 
> http://www.flickr.com/photos/51115445@N00/331719464/
>
> Secondary tuning setup:
> http://www.flickr.com/photos/51115445@N00/331719457/
>
> ********
>
> So far so good.  So I hooked up the primary and the MMC (which I had
> tapped for 10.2 nF... see pic).  But I couldn't figure out how to wire
> up the tank circuit so that I could get a reading off my oscilloscope of
> the response to the injected RF signal (I tried several configurations,
> plumbing the Internet for sources, but couldn't get anything to work ...
> my voltage rises were all in the over 1 MHz area).
>
> I decided to compute from readings off my RLC meter, and found that I
> needed to tap near the end of my 14th winding (with the 10.2 nF cap) to
> get a resonance of 205K.  But even with this setup, I couldn't get the
> scope to give me any readings at all in the low kilohertz rang.  Here
> are more pictures of the setup.  I also tried to test the complete coil,
> but that didn't work either.
>
> Measuring impedance of MMC: 
> http://www.flickr.com/photos/51115445@N00/331719460/
>
> Trying to measure resonance of primary coil: 
> http://www.flickr.com/photos/51115445@N00/331719462/
>
> Measurements for complete Tesla coil: 
> http://www.flickr.com/photos/51115445@N00/331719463/
>
>
>
> Can anyone give me advice on where I am making my mistakes here.  From the

> descriptions I've read on the Internet, tuning the primary should be 
> straightforward (but no one tells you how to wire up the test setup).  You

> are looking for two peaks with a valley at the secondary resonance 
> (indicating the secondary is drawing power away from the primary circuit)
>
> Thanks in advance for the help
>
> Chris Westland
>
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> -- 
> ____________________________________________________
>
> J. Christopher Westland, PhD CPA
> Professor, ISMT, University of Science & Technology, HK Clearwater 
> Bay,Kowloon, Hong Kong
> Tel: 852 2358 7643
> Fax: 852 2358 2421
> Mob: 852 9528 1745
> URL: ihome.ust.hk/~westland
> Mobile e-mail: chris.westland@xxxxxxxxxxxx
>
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