Next message: Roger Rippy: "lv-ab: Ground plane"
Jerry Peters wrote:
> Hello group - This is my second post regarding SSB installation
>
> Three quick questions if I may. First, I understand that round wire is
> invisible in the grounding system and flat sheet or screen copper is
> required/preferable. If screen is used, what are the critical
> characteristics - grid size, wire size, etc? I am concerned that the screen
> is just a bunch of small round wires. Second question is related. It is
> recommended to use several isolation capacitors for establishing the
> connection to the engine or other DC ground to avoid a DC ground loop
> between the antenna system and the radio. Once again, aren't the lead wires
> to the capacitors round wire and won't they "disappear" electrically? Third,
> is it important to keep the ground plane below the water level?
>
> My current plan is to laminate the interior of the hulls (catamaran), above
> and below the water line, with copper "insect screen" and tie it to the
> engine ground, water tank, etc with 3" copper straps and pull it all back to
> a single point at the tuner.
>
> Opinions?
>
> Jerry Peters
>
>
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> .
>
Jerry
RF only uses the skin of a conductor therefore surface area is the only
consideration. A 3 inch copper strap has the same surface area as a 1.8
inch diametre cable and is a lot cheaper. The reason a wire is not
recommended is that it would not have enough surface area to serve as an
effective counterpoise. If component wires were invisable to RF how
would they build a radio?
Keep the counterpoise below the waterline if you want it to work.
Remember you are coupling the RF to the sea through the counterpoise.
I use a dozen capacitors to attach the 3 inch counterpoise strap to the
tuner 3 inch ground strap. There is a 1/16 inch seperation between the
straps which is bridged by the capacitors.
--
Brian Stewart
Pilgrim
Whitby 42 #304
VB8320 VA3PIL
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