RE: Gap turn off at zero current and TVI
Hi Malcolm, Gary, all.
I would just like to clarify something that I didn't explain very well.
> ....It may turn out also that capacitive coupling of
> the interference to the SECONDARY COIL which may act as a simple
> radiator could kill the idea.
> ....Beyond the Fres,
> was there any difference in performance that may indicate different
> quenching. .... Upon further reflection,
> it may well be that the TVI is caused by VHF action on the part
> of the STREAMERS themselves....
I forgot to say that I have NO SECONDARY COIL in my aluminium test box.
All I have in my test setup is a primary cap, primary coil and a static
spark gap. (Similar setup to what Terry used in his paper.) The TV
interference is the same with this test setup as with my complete 2kW
coil throwing 3ft sparks. (No noticeable difference.)
>From this I deduced that the VHF bursts in the spark gap are the cause
of the TVI, but I agree that even if we can find a magic cure for
the gap noise, TVI could return when the secondary coil and streamers
are added :-(
Gary, I will try the little cap across the primary of my complete coil
to see if there is any change in spark length.
I am interested in the idea of smacking a discharged cap across the gap
to force the gap to quench, but I cannot think of an easy way to
implement this ! (Maybe some kind of multi-electrode rotary, kind of
like a change-over switch. This cap would also need discharging ? )
Although this could probably force a quench earlier, I don't think it
would help prevent the VHF bursts before the quench occurs.
There may be some shorting effect caused by putting the primary winding
in an Al box, but it does not seem to make much difference.
Thanks for the ideas, I now have much to ponder.
- In sunny Newcastle.