RE: [TCML] Tuning a coil with an oscilloscope

["S&JY" <youngs@xxxxxxxxx>]

Dennis,

Some tips:  1) The secondary resonant freq (Fres) is very sensitive to
nearby objects, including you, when you are making measurements.  You need
to be some distance from it, as you would be during normal operation, to
make a good measurement; 2) The streamers/leaders add some capacitive
loading to the secondary during operation, which lowers its Fres.  So when
making measurements, attach a wire the length of expected streamers to your
toroid, and suspend the other end of it with string so the wire goes out
horizontally; and 3) When measuring the primary Fres, You need to either
remove the secondary or at least the toroid, or short the top and bottom of
your secondary together, so it won't interact with your primary
measurements.

--Steve Y.

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of otmaskin5@xxxxxxx
Sent: Wednesday, April 30, 2008 6:32 PM
To: tesla@xxxxxxxxxx
Subject: [TCML] Tuning a coil with an oscilloscope


I have been trying to use a signal generator and scope to tune my coil more
scientifically than the old fashioned trial-and-error method. I believe I
pegged the secondary frequency at 127.24 kHz. This is pretty close to the
freq I got from JAVATC which was 125.21 kHz. 

However, in trying to tune the primary, I'm coming up with a tap point 13
5/8 turns which is significantly different from that the JAVATC indicated
16.2 turns.? This makes me think I might be doing something wrong.? 

A couple of questions:

1. Should you tune the primary coil while it is still hooked up to the NST &
Terry filter?? Or do you need to disconnect everything & totally isolate the
primary coil and tank cap?

2. Would someone out there be able to point me to a source showing how to
properly hook-up the scope & signal generator for both the primary &
secondary?? Just want to confirm I got the circuits right.

Thanks for any help.? Dennis Hopkinton MA

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