Here I took my chances in a magnifier Tesla coil setup. These are rough first tests but gave some interesting results. Tests were done with normal flat primary. This will upset a few people but who cares I did it anyway. The power input was 10Kv 25ma. My rotary spark gap was used but not running, more like a static gap. The gaps were closed right down to limit input power. I always do this for a new setup. Its best for it to explode at a lower power than full power ;-)

Coils used were 212khz,316khz,440khz and 661khz. These were measured with a scope to find the exact frequency. There will be a slight margin for error give or take a kHz or 2 but close enough for me. The quick spark gap was setup like below..

On the left is a copper pipe. This was grounded to Earth. To the right is the top end of the coil. In all cases this was the 212khz coil. Ontop is tinfoil, I use this for a connection when the toroid is normally ontop. This time there is just a small metal screwdriver which you can just see on the top left of the coil. The 212khz coil was tested a few times and the max output spark I could get was 6". Each run was just a second. Sparks would tend to arc bright for a second then just give random hits to the ground wire. Actual running gave mostly corona around the screwdriver. All tests were done for the first second or 2 of power-up.

I also tested each coil on its own to see what the output was. Each coil gave hardly anything in terms of output. I got about 1" off the 316khz coil. All other coils there just just a slight crackle from the screwdriver. Each coil was of course tuned by adjusting the primary tap to find best output.

Here is a better view of the top of the coil.

Below shows how the coils were connected...

In the middle is the 316khz coil. Just off the pic on the right is the 212khz coil. Between the 2 coil you can Just make out the small black connection wire. Results might have been better with a thicker cable but it was consistent for all tests so it was considered irrelevant for these tests. The 212khz coil ( right ) was placed on a small chair. I tried to keep the 212khz above the driver coils to prevent induction between the 2 coils. It was however a problem as I was limited on space. You can see the coils are close to each other and could give some induction. Going by other tests in the past I didn't see this as a problem as coils have been tested in and out of induction areas anyway.

Below is how the driver section was connected up...

Here you can see the flat primary coil and the driver coil in the middle of it.


661+212 coils series gave 7" sparks
440+212 coils series gave 7.5" sparks
316+212 coils series gave 8" sparks
212 coil on its own gave 6" sparks.

You can see from these results that the higher frequency coil gave worse results than the larger lower frequency coil. With the 316khz coil as the driver and 212khz as the secondary, it actually gave 2" more sparks, that's about 30% more power output.

The 212khz coil gave best output even though really, it should have been to big for the NST to power. The sparkgaps were worked very hard and would heat very fast. Even after a few seconds run they would not fire at all. A few second latter and they would work again for a few seconds. It should be noted there was no air blast or anything so this didn't help matters much. I guess with the RSG running results would be a lot better but as I was limited on space I haven't tried this. It does however make me wonder what results I would get with the RSG running as this should deliver near full tank capacity into the system. Soon I will try this and see what happens. It will put a lot of stress on parts but hopefully it will hold out well enough to test full power tests. I also wonder what would happen if the driver and secondary coils were reversed. I may try this also soon.

UPDATE December 31, 2001

Test's were done today with 212kHz coil and 316kHz coil. Rotary spark gap was used in this case and the results were a little different than the static tests.

212kHz coil gave 17" sparks
316kHz coil gave 16" sparks

Series coils with the 316kHz as driver gave 17" sparks. Tests were repeated many times and I took constant strike's to the ground wire as the maximum distance.

It is clear now that something has changed in the system since the rotary was used max spark length has increased but the series coils gave no extra output. It is clear however that the rotary gap gave much better results than the static gaps. In this test it was clear series coils didn't appear to give any additional output. I Also tried adding some extra capacitance ontop of the coil though this didn't appear to give any effects on spark lengths. I have yet to try the smaller coils for series tests. Soon I will try a closer coupled primary.


UPDATE January 1, 2002

Tests were done with a new vertical primary. Spacing from driver coil to primary was about 3" gap all the way around. The smaller 661kHz high coil was tested along with the larger 316kHz coil. Both tests gave no extra power output on the 212kHz coil. In this case it was about 16" or a little bit more. With the higher frequency driver ( 661kHz coil ) the frequency seemed to be a lot higher in running and the sparks moved about a lot faster. With the new primary there was streamers coming off the bottom connection of the 212kHz coil ( secondary ). It would appear as if the voltage on the base was increased, which could be so as the primary coil was closer to the driver. The sparks from the base of the secondary coil were over 2inches , they were arcing the the small chair I had the coil standing on. Its clear this will be a loss and so reducing it needs to be done. If its reduced 2" from the bottom it might increase 2" at the top end with would give over 18" sparks. I doubt it will work like that but reducing the "leeks" can only give better spark length.

I am also thinking if this system works a little better then I could build a smaller primary to increase coupling even more. This will of course be a problem to insulate the primary from the driver. It will take time to build a new primary so I don't know when this will be finished. Soon I hope to better the transmission line.