[Amps] placement of RF choke bypass cap.

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Wed, 17 Mar 2010 07:24:00 -0700, "Jim Thomson" <Jim.thom at telus.net>
wrote:

>##  How do u know there will be  RF  flowing on the underside
>of the chassis ?? ... asuming it has a ..'normal' chassis .
>If the grid trip is below the chassis, and also uses rf bypass caps,
>it should not be a problem. ... at least on paper. 

REPLY:

The RF will be flowing through the thickness of the chassis, both
sides. This is not a transmission line or piece of coax. 

And the problem with the grid trip or other circuit is not easily
cured with bypass caps used in the ordinary way. The problem there is
a ground loop condition, which acts like a little "RF generator",
injecting RF into anything connected across part of the loop or from a
point on the loop to a different ground. . It's best to just stay away
from the loop entirely. And better yet to not create one that long in
the first place.

A certain amount of ground loop in the tank circuit is unavoidable if
the tune and load caps are mounted to the chassis, but to create a
second one 11 inches long is ridiculous. 

73, Bill W6WRT