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: Mon, 25 Dec 2006 08:46:26 +0800
From: westland <westland@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Please Help!  Trying to tune the primary coil (fwd)

Hi Jim:

I'm basically trying to figure out where in the tank circuit to clip the 
red and black clips on my signal generator and my o-scope

I was certain that this must have appeared in the archives  ... 
somewhere ... but whereas there is an enormous amount written on tuning 
the primary,  I can only find one comment by Finn Hammer concerning 
where the o-scope and signal generator should be hooked up ... I've also 
seen generic diagrams for measuring frequency of tank circuits.  It's 
just that every interpretation I've given to the implied clip points so 
far has given my silly results in searching for resonance ... finding 
the resonance point was so easy with the secondary, and it matched right 
up with MapTesla's resonance figure (187KHz for MapTesla; 205KH actual).

I'm sure that this is so straightforward that I'm missing the obvious . 
... whatever the case, I am missing the obvious

Chris Westland


Tesla list wrote:
> Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Sun, 24 Dec 2006 13:00:28 -0800
> From: Jim Mora <jmora@xxxxxxxxxxx>
> To: 'Tesla list' <tesla@xxxxxxxxxx>
> Subject: RE: Please Help!  Trying to tune the primary coil (fwd)
>
> Hello,
>
> Terry explained this pretty well in the archives.
>
> Jim Mora
>
> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx] 
> Sent: Sunday, December 24, 2006 5:07 AM
> To: tesla@xxxxxxxxxx
> Subject: Please Help! Trying to tune the primary coil (fwd)
>
> Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Sun, 24 Dec 2006 20:34:19 +0800
> From: westland <westland@xxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Please Help!  Trying to tune the primary coil
>
> Hi All:
>
> 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