[TCML] RF Ground and Brass

[bartb]

Hi Phil

FIFTYGUY at aol.com wrote:
> In Dan McCauley's "DRSSTC II" book, he shows  simulation predictions of 
> secondary base current of ~8A peak, and measured of  ~5A peak. These are of 
> sinusoids in 300uS square-ish pulse envelopes at 100  bursts per second. I can't do 
> the math on that one, but it seems to me that it  works out to "a lot less than 
> 1 amp RMS continuous". This on a 1kW coil. 
>   

Exactly! I don't know if you missed my statement in my original response 
to Gary that this current is time dependent and that a smaller wire size 
would certainly be ok if not a long length (and even then, how long?). I 
don't know how long. I can probably figure this out however as it's not 
rocket science. Some systems can run 15A peak. Some only a few amps. But 
in all of these, the off time between bursts is part of determining the 
power requirements. Base currents are there only during the energy 
transfer time (then nothing until the next transfer). The problem is you 
can get systems running high and low off times, so that needs to be 
looked at. I'm not a believer in "one size fits all".


> 15/60 NST, as 350mA RMS.
>  
> If we were passing 10A RMS through our secondary bases, the typical 6" 
> coil wound with ~ 25ga wire would probably self-destruct very quickly! 
>   

If we were running 10A rms "continuous", then yes.
>  
> It *does* seem a bit silly to splice a piece of  10ga THHN to a the 
> bottom of two thousand feet of 25ga like it's going to make  a difference! 
>   

Doesn't seem silly at all to provide a low impedance path to ground.

Take care,
Bart