Re: Strange behaviour of a VTTC (13MHz?)

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 1/22/01 1:43:55 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

> This can't be an error signal, as the signal grew enormously
>  as we turned up the anode voltage. The (Tektronics) scope
>  isn't broken, since it had just come from service, with no faults.
>  It was connected to a grounded outlet.
>  
>  We eliminated all potential noise sources: turned off all lights,
>  mobile phones, power supplies... (except the scope)
>  
>  Maybe tube coils are not for us after all?
>  
>  -- 
>  - Antti

Antti,

Maybe a ground loop in your AC wires and scope, etc.  You may
be able to plug the scope into a ungrounded outlet to stop this.
Use one of those adaptors for grounding to ungrounded outlets,
but don't connect the ground.  Just connect the ground from
one of your instruments, not all.  I was going to say that's it's
parasitic oscillations, but since it occurs when shut off, it's
most likely not that.

I used to see these ground loops in industrial video equipment
causing 10mHz + oscillations often..  Had to play around with 
the grounds, etc to get rid of it.

John Freau