primary spacing
Cain, Sun Apr 15 2007, 02:33PMi just finished my coil (well after the many prototypes) and i am still not getting a good output
NST 15kv 30MA
primary 1/4" 14 turns 1/2" spacing 10° dish
secondary 20.9" tall 4.3" dia
RF chokes and safety gap
thick wire for power routing
10 gap TCBOR type gap (with high volume barrel fan sucking though gaps) total gap of about 7-9mm
bottle cap (clear glass) 6 bottles 0.0065 uf, .7 bottles 0.0076uf (no visible corona)
tried lots o different toroids
RF ground 3 feet rod
I'm only getting an output at about 14-15 inches max.... what is wrong? (RF output is huge as i would think from a SGTC i am getting a small shock from my Variac 0-280V 8A and any other metal object i touch)
are my primary turns to far apart?
would i be losing that much using an alligator clip to connect to the primary?
Re: primary spacing
GreySoul, Sun Apr 15 2007, 10:05PM
One amature helping another, if I may:
Is the primary 1/2" on center or 1/2" edge to edge? that would make a slight variation in performance for a given tap point.
Also, have you tried a flat planar primary? I've been advised not to mess with dish primaries until I get my flat primary well tuned. it's easier to keep it perfectly perpendicular to the secondary that way, which affects coupling.
For a tap connector try this: Go to radio shack or any parts store and buy a little bus fuse holder for the 1/4" fuses. Pop out the 2 metal clips and you'll have a pair of great clips that you can solder to your HV in and snap to the primary anywhere with a great connection.
...grounding rod. I have 2 8' 5/8" copper clad steel grounding rods placed about 6' apart. they make a good HV/RF ground and are well away from the 220 service entry and it's ground. 3' may not be the most effective ground rod you could get.... especially in dry soil. copper clad grounding rod is sold at home depot.
spark gap... have you tried with a plain old static spark gap? *shrug*
the only other thing standing out to me is the 6.5 / 7.6 uF tank cap... my MMC is 0.01uF @ 30KVDC and runs LTR on an SSG. all day with no problem. 6.5 seems...huge....?
good luck, hope I helped?
-Doug
GreySoul, Sun Apr 15 2007, 10:05PM
One amature helping another, if I may:
Is the primary 1/2" on center or 1/2" edge to edge? that would make a slight variation in performance for a given tap point.
Also, have you tried a flat planar primary? I've been advised not to mess with dish primaries until I get my flat primary well tuned. it's easier to keep it perfectly perpendicular to the secondary that way, which affects coupling.
For a tap connector try this: Go to radio shack or any parts store and buy a little bus fuse holder for the 1/4" fuses. Pop out the 2 metal clips and you'll have a pair of great clips that you can solder to your HV in and snap to the primary anywhere with a great connection.
...grounding rod. I have 2 8' 5/8" copper clad steel grounding rods placed about 6' apart. they make a good HV/RF ground and are well away from the 220 service entry and it's ground. 3' may not be the most effective ground rod you could get.... especially in dry soil. copper clad grounding rod is sold at home depot.
spark gap... have you tried with a plain old static spark gap? *shrug*
the only other thing standing out to me is the 6.5 / 7.6 uF tank cap... my MMC is 0.01uF @ 30KVDC and runs LTR on an SSG. all day with no problem. 6.5 seems...huge....?
good luck, hope I helped?
-Doug
Re: primary spacing
Cain, Sun Apr 15 2007, 10:45PM
oh woops yeah my cap values are wrong lol I'll edit that... and the TCBOR gap is a static gap i use 1/2 copper pipe as the electrodes too
Cain, Sun Apr 15 2007, 10:45PM
oh woops yeah my cap values are wrong lol I'll edit that... and the TCBOR gap is a static gap i use 1/2 copper pipe as the electrodes too
Re: primary spacing
GreySoul, Mon Apr 16 2007, 02:22AM
sorry yeah I knew it's a SSG... but a multi-segment one... I was talking about 2 electrodes.... easy to tune, but lossy.
GreySoul, Mon Apr 16 2007, 02:22AM
sorry yeah I knew it's a SSG... but a multi-segment one... I was talking about 2 electrodes.... easy to tune, but lossy.
Re: primary spacing
Cain, Mon Apr 16 2007, 05:49AM
well i did some tweaking and i think it was just that my gap was a lil large and i watered my ground rod and and now getting close to 20 inch strikes still should be a bit better
Cain, Mon Apr 16 2007, 05:49AM
well i did some tweaking and i think it was just that my gap was a lil large and i watered my ground rod and and now getting close to 20 inch strikes still should be a bit better
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