Re: Primary Tune Found
>>From ccurran-at-execpc-dot-comTue Aug 13 15:20:16 1996
>Date: Tue, 13 Aug 1996 08:30:20 -0500
>From: Chuck Curran <ccurran-at-execpc-dot-com>
>Subject: Primary Tune Found
> One interesting item that I noticed last night. I am using RG-213 for
>my high voltage leads from the pig to the spark gap. At the spark gap I
>have taken the grounding braid or outer conductor from both leads and
>soldered both to a 1 1/2" braided copper ground strap. This strap is
>then connected directly to my system ground and is about 8' long. The
>RG-213 is 30' long and is then connected to my filter board at the pole
>pig. O.K., what I did was strip back and had about 12" of the coax
>ground braid laying out from each high voltage lead and the two ground
>braids were laying against each other, but not connected to anything. I
>figured since the other end was clearly tied to ground, why do it
>again. The majority of the 12" was laying on the driveway. These two
>ground leads were arcing, one to the other, with about a 1/2" diameter
>ball of blue light. No noise was heard and no damage detected, but it
>was a surprise.
<el smaller snippo>
>Enough for now--any comments or recommendations would be appreciated.
If I understand you correctly, I believe that with the shields of the
two RG-213 cables you have created a single turn loop with the center
point grounded (at the coil system), and a happenstance proximity spark gap
across the open ends (where you saw the blue light). This is exactly what Heinrich
Hertz used as a receiver to demonstrate received energy at VHF wavelengths in the
world's first achnowledged radio transmission experiment.
This single turn (braid) is in parallel to the HV leads going to your pole pig filter.
The RF getting past the rotary break and heading towards the pig is inducing
voltage in your shields. This is OK. At the pig end, just isolate these two shields
so that they are insulated and float. The shields will then do just
that, shield RF radiation from escaping from the HV runs. If you tie these shields
together , and or ground them at the pole pig station, you will
create a loop and radiate RF bigtime. Run a common point ground as
you've started to do, with all subsystems grounding at the base of
Congratulations on the performance you are now achieving. You've
just entered the big league!