Re: Guy Atkins' E100 IF Filter Modification Article

Steve Ratzlaff <steveratz@...>

Hi Guy,
You marked the filter common/ground pin properly. This "ground" is a matter of convenience for the circuit designer. It's an AC and RF ground not "ground" as referred to the common of the rest of the board or to the negative terminal of the battery or external power supply. As long as the filter sees an RF ground then it's happy; it doesn't matter if there's actual voltage on it (which there is in this case). And the stock filter is a plastic case so never would see any possible shorting to the "real ground" that the bottom shield on the display board presents.

----- Original Message -----
From: Guy Atkins
Sent: Saturday, December 06, 2008 11:52 AM
Subject: Re: [ultralightdx] Guy Atkins' E100 IF Filter Modification Article

Hi Steve,
Thanks for your useful comments. The E100 owner who plans to do this mod can benefit a lot from your advice.
I'm curious about your comment regarding the ground point on the main board actually being a positive voltage point. Unless I marked the illustration wrong, this was the stock thru-hole used by the original filter's ground pin. I can't see why positive voltage would be applied to the stock filter, a passive component.

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