Re: Need Help with 15 degree Primary Support System
At 05:25 PM 7/20/99 -0600, Tesla List wrote:
>Original Poster: Esondrmn-at-aol-dot-com
>I am convinced that the coupling can be adjusted from too loose to too tight
>when using a flat primary with most coil designs. Both my 6.0" and my 3.0"
>coils use flat primaries with the first turn of the secondary set just about
>even with the flat primary windings. When I was using the inclined primary
>on the 6.0" coil, I had to raise the secondary up about 2.0" to prevent
>overcoupling. On the other hand, using a slightly inclinded primary makes it
>easier to get the tap lead under the primary if you don't have cutouts in the
>base for direct access from the bottom.
>BTW, compared to an inclined primary, with a flat primary you will have to
>lower the secondary (or raise the primary) to promote tighter coupling.
Hi Ed, All,
I posted an update to this today but I went to using HDPE for the flat
primary supports and it's working out great. The supports are 1 1/2"
high and the tubing is center with the first turn of the secondary coil. I put
a 1/2" wooden disk on the bottom of the secondary on top of the already
sealed disk inside of the secondary. The 1/2" disk has two 1" brass bolts
that go through the toplevel of the table top, that holds the primary coil. I
did it this way so I can remove the secondary coil and it also makes it easier
for transport and storage purposes of the entire table unit. The brass bolts
will get grounded. If I need to adjust the secondary height upwards, I can
loosen the nuts and insert leftover pieces of 1/2" HDPE underneath, and
re-tighten. I plan to tack the primary supports down with a light glue
until I can get the entire unit wound. Once wound, the tubing will keep
the entire support system together as a unit. If I need to raise the primary,
I can tap lightly to loosen each support and use HDPE shims to get the
necessary height. I've tried to cover it so adjustments can be made on
both the primary and secondary, if necessary for coupling. Hopefully,
I won't have to do much adjusting. There will be enough room underneath
the tubing for a tap on the primary.
Since this is my first coil, I've learned a few things while building it. Next
time I wind another secondary, I'll go down to Walmart, spend $25 and
buy a separate rotissierie unit for the winder part of the jig. I've seen
pictures of Terry Fritz's winder and that is probably the ultimate in
winding jigs, but I'll keep mine a bit simpler. :-)
I have experimented with using spark plugs in a spark gap unit.
They work great! Come to think of it, a car distributor with the rotor
contact points combined with spark plugs and the coil is a decent
spark gap unit on it's own. I'm using the standard RQ cylindrical
spark gap with copper pipe but I'm always looking at ways to improve
the spark gap. I did find some nice 3/8" lamp finials at Home Depot
that have a hole at one end for a 8/32" bolt and bought about 20 of
them to try for a future SG unit.
I also discovered that I WILL need to get a drill press, since it's almost
impossible to drill a series of holes in any material straight enough by
hand. For the primary supports, once I laid out the line with the marks
for the holes, I used an awl to get the center point in the HDPE, and the
a 1/4" drill bit to finish. It's rough but it works.
"Resistance to tyrants is obedience to God" - Thomas Jefferson