[C38] Grounding Plate

[Tom T.]

Hello Larry, I hope I'm not too late answering your email.  I was on the
boat for a week without a computer and I'm now I'm behind in reading my
email and I somehow missed yours.

The Catalina 38 has a lead keel which makes a very good SSB ground if you
tie your counterpoise of the antenna to the keel using low inductance
cables.  Boats with encapsulated internal ballast don't have our advantage.
I have a SSB on my boat and I tied all my grounds together to the keel both
for lightning protection and SSB efficiency.

Your keel does NOT have to be bare metal to make a good SSB ground.  The
grounding current can pass right through even very thick fairing material
with little or no loss of efficiency because at HF frequencies, there is
great capacitive inductance making any minor insulation from paint and
fairing material virtually invisible to the SSB current.

The big trick is to get very low inductance connections from the ground of
your antenna (counterpoise) to the keel.  This requires using either flat
plate straps or non-braid cable with minimal bends between the antenna base
and the keel.  Any bends in the connecting ground cable will cause an
inductive reactance which is a fancy name for resistance on an alternating
circuit.  The higher the frequency, the higher the resistance.  Keeping
this inductive reactance to a minimum is very critical for good SSB
performance.

Good luck,
Tom Troncalli
(aka AB4NI)



> [Original Message]
> From: Larry Malmberg <larrypi at linkline.com>
> To: Catalina 38 Listserve <listserve at catalina38.org>
> Date: 12/1/2008 12:34:45 PM
> Subject: [C38] Grounding Plate
>
> A while back we were in an emergency repair situation in National City,
CA,
> another boat was up next to ours and he had grounding plates affixed to
the
> underside of the hull.  Now the gentleman that owned the boat told me that
> he though it was for lightening strikes but was not sure.  I was thinking,
> well here goes, that this would be a great way to ground a SSB Radio.  Has
> anyone done this with a Catalina 38?  Any advice out there?
>
>
>
>
> Best regards,
>
> Larry Malmberg
> Hassle
>
>
>
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