On 7/8/13 1:04 AM, Jim wrote:
FWIW, I met an engineer who told me that the spark gaps are what create all of the emi. He said when they fire they cover infinite frequencies.
well, not infinitely..The fast rise time when the gap fires does create a very wide band of frequencies. However, not all of them are radiated equally. Terry Fritz made some radiated RF measurements on a spark gap coil with a spectrum analyzer and my fuzzy recollection is that he found the (broad) peak in the spectrum had a frequency that depended on the length of the wires (all up in VHF spectrum).
This makes sense, the gap is basically at the feedpoint of an improvised dipole antenna with a bunch of weird stuff at the end of the dipole.
There was some discussion about whether suitable ferrites could knock this down, but there are a lot of tricky aspects to that. You don't want to be slapping some number 43 mix beads on the HV gap wires randomly.
If it is "radiating" from the gap wires, then running the wires to and from the gap next to each other (suitably insulated) will greatly reduce the radiation.
_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla