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

"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.

http://www.sailmail.com/grounds.htm

This should answer all the questions you posed.

Jack Painter
Virginia Beach VA

Jack - thanks for the link to Stan Honey's excellent article. It is a great
reference but it still leaves me with the questions that I posed to the
group.

"Jerry Peters" wrote
Jack - thanks for the link to Stan Honey's excellent article. It is a
great
reference but it still leaves me with the questions that I posed to the
group.



Jerry, I don't think you read the article. It specifically address your
questions, and that is why I referenced the article. Not to provide some
kind of distraction from your query. Look again please, and READ the
article. There is a section just about RF grounds that answers all of your
questions, from wire v. strap to capacitor sizing and number of required to
hull plates.

Jack

Hi Jerry,

I see the "grounding article" answers few of your questions.

First, round wire will work just as well as strap for a ground lead.
Round wire is not "invisible" to RF. That said, surface area is what
is important in the wire for a low inductance lead. You can connect
several round wires in parallel and accomplish the same thing as you
do with copper strap.
It is generally easier to use strap.

Copper screen works well also. All those round wires in the screen are
shorted together to make a large flat surface to RF. But if it gets
badly corroded then you may not have good connections between all
those wires.

Isolating the ground lead with capacitors can be a good idea in some
cases. You want to avoid multiple paths for the DC current of the
radio to flow through as it can place a small DC potential between
elements that are in the water. In other words you don't want any of
your ground bonding leads to carry any DC current as the small voltage
drop that results in the wire will place a difference voltage between
grounded items. (through hulls etc.)

As for isolating all underwater elements and not bonding them, I don't
subscribe to doing that. It would be ideal if you could guarantee that
it stayed that way but it would take constant vigilance to maintain
it. Any partial short or leakage to any of the underwater elements and
you will have big problems with galvanic corrosion. At least by having
them all bonded you have a better chance of keeping them all at the
same potential.

A ground screen for a radio ground can work well if it is large
enough. The old idea of a ground screen on the fly bridge being
adequate is a joke. It takes a large surface area to be effective. It
may work well at the very high frequencies but will fail miserably on
the lower bands.

You best bet is to mount the tuner low in the boat with as short as
possible ground leads to underwater elements. The sea makes a pretty
good ground.

Your idea of putting the screen in the hull and tying it ao everything
else is good. Make it terminate very near where the tuner will be.
Running a long ground lead to all that stuff will negate all you
efforts. Also get a connection to underwater elements to the screen.


Do a search on this group for antennas and grounding.

Regards
Gary






On Sun, 8 Aug 2004 07:55:29 -0400, "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

Thanks much - very informative