[Prev][Next][Index][Thread]

Re: RQ gaps

In a message dated 4/18/00 1:10:08 PM Central Daylight Time, tesla-at-pupman-dot-com 
writes:
>>>Jochen just recently posted his improved scott gap design.  I took a
 look at it and plan to construct one soon.  It appears to be quite
 accurate and quite easy to construct.  This is espicially helpful for
 the beginner like me, where i don't really want to machine precise
 grooves for a gap.<<<

Brad and all,
Having built a very nice modification of Scot's gap, I see that it is not 
necessary to
machine the furrows to hold the copper tubing. I used 1/4-inch G-10 and used a
8-32 screw with lockwasher and nut to hold each 1.5 inch diam copper sweat 
coupling to the G-10. The cylinders hold solid, no machining needed. An 
earlier
posting suggested using a section of aluminum U-channel to seat the cylinder.
Again, I don't think this is necessary. The Al makes a nice heat sink but the 
mass
of the copper and the air blower keep the heat well within the tolerance of 
the G-10.

Then, another multigap using copper sweat couplings and also allowing a 
choice of
the diameter and the number of cylinders can be built on any rigid insulating 
substance. The cylinders are mounted vertically on 3.5 inch 8-32 screws. Each 
cylinder is squeezed in a vice so it is made elliptical. It rests on a shelf 
on each screw around an inch above the base and is held tightly in place by a 
brass cleat tightened down with a nut.

The gap is adjusted by rotating the cylinders around their screw mount. Right 
now,
this is the gap I am using for my bipolar. I have 5 pieces of 1-inch copper 
sweat
cylinders. The gap is very easy to build and adjust, and it is very easy to 
clean.

As mentioned in an earlier post, I have also noticed that the gap seems to 
work best
when the two outer gaps are set to as much as 0.005 (0.028) larger than the 
three center gaps. Does anyone know why? I see the primary NST current for 
one 30 mA and one 60 mA NST in parallel rise to 9 Amps (70 uF PFC) before 
ignition. Then things settle down to a nice sweet 5 Amps with a nearly 
20-inch arc. Neato.

Happy day,
Ralph Zekelman
















  >>