Re: A SSTC Ground ?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Finn,

At 11:11 PM 9/16/2003 +0200, you wrote:
>Comments inbetween:
>
>Dan wrote:
> >
> > Forget about taking any type of sensitive measurements within the vicinity
> > of an SSTC.  Protect all electronic devices and equipment.
> > Use an analog meter if you need to take measurements.  Its not worth the
> > risk of damaging an expensive scope, etc...
> >
> > Dan
>
>It is more difficult to measure under these circumstances, for example
>does a Pearson 101 monitor report much more noise at 25MHz than a 2100
>does. Which is strange since the 2100 has a -3dB point at 20MHz whereas
>the 101 drops off at 4 MHz.
>Running the coil in half wave rectified input, the scope simply looses
>controll of itself. The reported amplitude tracks the trigger level, and
>if not triggered, the signal amplitude rises and falls in a 5 sec.
>cycle.
>
>But I don`t have an education as a radar engineer, so I need
>measurements more than usual, to understand what is going on.

Sounds like you may be getting radiated noise or coupling current into the 
grounds.  Try moving cables around perpendicular to the coil's high 
currents.  Ground loops by also be an issue.  That coax to the Pearson can 
be a big antenna back to the poor scope!!  The scope itself may need a good 
RF ground.  Often just moving cables around can get rid of a lot of 
noise.  Even the AC line to the scope can really mess things up if it is 
picking a few amps of RF off the primary...

Cheers,

         Terry