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Re: Primary Q's and Spark Gaps

You wrote: 

Ed,
Don't know how the other guy's do it, but here is how I built my
saucer primary:
Found the center of a 2X2' 3/4" plywood and scribed an 8" circle
in the middle.  Cut 1X6" grade #1 douglas fir at about a 15 degree 
angle with a table saw along the grain so it results in 2 pieces 12" 
long and about 1.5" at the small side and about 4.25" on the big side.  
I clamped these together and used my belt sander to even them out.  
Then I drilled 1/8" holes on .25 centers about a half inch from the top 
of the angled side.  Now its time to scribe two more circles on the 
plywood.  I did mine about 13" out from center and about 19" out.  Then 
scribe intersecting lines from corner to corner and from side  to side 
like spokes in a wheel on the plywood.  Drill holes where the circles 
and the "spokes" intersect.  I used 1/4" drill.  Mark the angled pieces 
(you can adjust how large or small your inner turn is here) and drill 
1/4" holes to corrospond with the ones you drilled in the plywood.  
Then glue it all together.  When it dries, place your tubing and use 
tie wraps to hold it together.  Don't tighten the tie wraps until you 
get the tube where you want it.  I used this for .250 tubing with .250 
spacing.  It holds 100' of tube nicely. If you are using .375 tubing, 
you will probably want to increase your spacing.  You don't want to use 
metal screws that will become a permanent part of the primary.  I did
use some drywall screws from the bottom to hold it together while the
glue was drying though.  Hope this makes sense to you.  I looked 
closely at pictures of coils that have been posted and just "winged it" 
to build mine.  It did take a couple of evenings to tweak the tubing
so it looks right.  I still give it an evil eye when I walk by it.
This worked quite well for me and I 'll use the same method again
with bigger dimensions to build a .375" unit with about a 14" inner 
turn shortly.

Glenn
 

  I have been trying to figure out how to 
>do a neat job of winding conical or saucer-shaped primaries.  How
>do you "big boys" do it so it looks good?
>Ed
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