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Re: Coil behavior



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Glen,

You have several choices (assuming the problem is really the fp>fs):

1. Lower the freq of the primary by increasing the Cp.
2. Add some offaxis inductance in series with the primary.
3. Increase the freq of the secondary by decreasing the topload capacitance.
4. Sometimes raising and lowering the topload can make small changes in resonance as well.

Gerry R.


Original poster: "Glen McGowan" <glen.mcgowan@xxxxxxxxx>

Hello All,

I'm afraid to ask but I think I may be lacking in primary turns. I'm running a resonate coil (poor planning on my part). That said I'm running very conservitave spark gap settings. One of the issues I'm running into is I have my tap connected to the very end of my primary (15 turns counting the tap lead). I dont' get streamers at any other position but the one I just mentioned. If I connect to turn number 14 I get nothing. I do notice however that my safety gap (Terry's Filter) fires solidly at turn 14 and any other turn for that matter and no streamers. The safety gap fires quit frequently even at primary turn 15 but more pronounced at 14. ( I just realized I should prolly open up the safety gap a hair while proof reading my post.).

My question is can I adjust anything besides adding extra turns to the primary? Can I use a smaller toroid, raise/lower the secondary or raise/lower the topload? I really don't want to re-build the primary. JavaTC says I should be tuning at 13'ish turns. I tried 13 and get nothing but a safety gap arc. I know I'm doing something wrong.


Transformer: 15/60
Primary: 15 turns of 1/4 copper tubing.  (including Tap lead.)
Secondary : 4" and 23" of actual coil on a 25" form. (first turn level with primary, maybe a hair above)
Toroid: 4x19 sitting at 25" high.
MMC:  .0093uF  (Ya I know I'll build another one)