Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Norman,
I have not heard of anyone using a slit toroid. You may be
experimenting into a topic that hasn't been looked into deeply. I
generally keep my toroid as high as possible (not allowing sparks to
issue from the top winding, well, unless I'm in a lazy mode of
operation). It's been stated on the list that a toroid low or
partially covering the top windings may heat the top windings (I
have not experienced this myself). It certainly appears the Q was
definitely affected. Out of curiosity, how did you measure fo?
Take care,
Bart
Tesla list wrote:
Original poster: norman@xxxxxxxxxxxxxxxxxxxxxxxxx
I just finished measuring the resonance frequency of my secondary
by observing
the null due to the series resonance of the 1/4 wavelength
coil. The toroid on
top of the coil was constructed out of 4", "semi-rigid flexible
aluminum duct",
bought in Home Depot. The ID is 3.5", OD 11.5" and the center of
the toroid is
hollow so that it slides over the PVC coil form. The coil is 9" x
3.5" wound
with # 24 wire and resonates at 500kHz.
I noticed that when the toroid was about 3" above the top of the secondary
winding the resonance notch was very deep, but when the toroid was
moved close
to the top of the winding, the notch was not very steep. Clearly the toroid
was affecting the Q of the coil, probably by acting as a shorted
turn. I have
not come across any information about how far the toroid should be
placed from
the top of the coil. Anybody have any information about
this? Should I place
a slit through the toroid?
Also the surface of the semi-rigid flexible duct looks like an accordion with
1/4" deep ridges spaced about 1/4" apart. Will this surface effect the
streamers? This is a low power Tesla coil that I hope will produce at least
10" streamers.