Hi Larry,
I apologise for seeking yet again to pick your brain but....

I am having a Pactor III (USB) modem installed as soon as I get my
mast back up again. The local technician who is goiung to do it and
whom I purchased the modem from tells me that I need the best earth
for data that I can get and that I should purchase a sintered bronze
earth plate. Granted, but my retired US Navy radio whizz in Malaysia,
Bob, spent a few hours getting our system tuned and earthed a few
years ago and said then that it was a good earth.

I don't mind shelling out US$200 if it will provide even a modest gain
in reception or transmission. What is your angle on this?

Given that I do buy it, where is the best place to install it, apart
from permanently below the water line?

Thanks in high anticipation.
cheers
Peter Hendra

By the way, I am changing all my existing galvanised 1x19 standing
rigging for stainless, mainly as the rust on the galv. looks terrible
after 14 years aloft. I wanted the old fashioned poured sockets when I
built this boat, couldn't get any so made a pattern and had them cast
from bronze. - wire is unravelled and a small bent back hook made at
the end of each one, re-ravelled and pulled down into the tapered cone
of the body of the socket and then filled with molten Camelia metal -
lead like. when I cut the sockets off, the wire was perfect and would
have lasted another 14 years - rust was only external. fo\restay has
always been stainless. The good thing is, that like stalock and
Norseman, they are reuseable but there is not the problem of galled
stainless upon stainless. The metal also can be reused.

On Sat, 21 Apr 2007 21:01:25 -0400, Peter Hendra
wrote:

Hi Larry,
I apologise for seeking yet again to pick your brain but....

I am having a Pactor III (USB) modem installed as soon as I get my
mast back up again. The local technician who is goiung to do it and
whom I purchased the modem from tells me that I need the best earth
for data that I can get and that I should purchase a sintered bronze
earth plate. Granted, but my retired US Navy radio whizz in Malaysia,
Bob, spent a few hours getting our system tuned and earthed a few
years ago and said then that it was a good earth.

I don't mind shelling out US$200 if it will provide even a modest gain
in reception or transmission. What is your angle on this?

Given that I do buy it, where is the best place to install it, apart
from permanently below the water line?

I have a Pactor III on my boat and we did nothing special for
grounding beyond what was already there for the SSB. If your existing
SSB is working OK I would not worry about it.

What *is* important is to use lots of ferrite RF chokes on all of the
inputs and outputs to the Pactor and to the laptop computer. This
will help to prevent stray RF energy from getting into the digital
circuitry and causing problems.

On Sat, 21 Apr 2007 21:11:11 -0400, Wayne.B
wrote:

My God Wayne, you're quick. I just posted this.

Thank you very much for the advice. $200 is $200 and I can use it
elsewhere. I shall install chokes as per your suggestion.

I am really looking forward to email at sea. I have had it previously
with an Iridium phone that my department head hired for me so that I
could continue to manage my project whilst crossing the Atlantic. As
they had paid for it, I did not feel comfortable in emailing friends
on non-government business.

cheers
Peter

I have a Pactor III on my boat and we did nothing special for
grounding beyond what was already there for the SSB. If your existing
SSB is working OK I would not worry about it.

What *is* important is to use lots of ferrite RF chokes on all of the
inputs and outputs to the Pactor and to the laptop computer. This
will help to prevent stray RF energy from getting into the digital
circuitry and causing problems.

Peter Hendra wrote in
:

I don't mind shelling out US$200 if it will provide even a modest gain
in reception or transmission. What is your angle on this?

Given that I do buy it, where is the best place to install it, apart
from permanently below the water line?



If you already have a good earth (ground to the Americans), adding
another one probably will make no difference. I would like the ground
(er, ah earth) cable that connects the HF tuner to the ocean to be
installed with NO SHARP CORNERS in the most direct path available. Make
SMOOTH, not necessarily neat, turns. NEVER make a sharp turn with coax
cable, I don't care how neat it looks. Sharp turns in the earth bus act
like little inductors in series between your tuner and your earth...not
good...raises the impedance of the earth to the tuner.

To show you how futile this is on a sailboat, let me describe the earth
used at an AM broadcast station.....

If we drive a 3 meter ground rod into the ground at the base of the AM
tower, which is the AM stations actual antenna like your backstay
probably is your HF installation, it will work. However, it will not
work "good"....near as "good" as 36 sections of bridge cable arranged out
horizontally, radially, from a big, heavy cable ring at the base of the
tower to hook the transmitter's earth to. It's called a "counterpoise"
and creates an artificial earth in even very poorly conducting soil.

Now, you can, while you're at sea traveling ahead and not backing over
it, create a pseudo copy of this earth with a single wire hooked straight
to the tuner's ground post, thrown directly overboard to trail out in the
ocean behind the boat...straight as you can get it. The longer the
better, but a good length is from 15-35 meters long. DON'T forget to
roll it up as you come into port so it fouls rudder or screw! This dirty
little secret is a MUCH better earth for your HF radio than anything
screwed under the hull. Even hookup wire will work, but a nice old piece
of stainless winch cable with lots of open strands that won't rust makes
a fantastic trailing-earth ground. Try it with and without....doing a
retune on the tuner as it WILL change the feedpoint impedance of your HF
antenna quite drastically, once connected.

No big $$$ outlay is necessary....just an old piece of stainless cable,
tied off to a sturdy handrail post or the base of the backstay below the
bottom insulator is fine. Don't worry about it sinking. If it were
100' STRAIGHT DOWN, which it won't be unless you're becalmed, that would
be BEST! It doesn't need a dragging anchor to attract the really big
fish, either. If you like, you can just trail it out when making HF
calls, then coil it back in to store it. Works great...

Larry W4CSC
--
Geez, a ham letting out his secret weapons...how awful...(c;

Larry wrote:

snip
Now, you can, while you're at sea traveling ahead and not backing over
it, create a pseudo copy of this earth with a single wire hooked straight
to the tuner's ground post, thrown directly overboard to trail out in the
ocean behind the boat...straight as you can get it. The longer the
better, but a good length is from 15-35 meters long. DON'T forget to
roll it up as you come into port so it fouls rudder or screw! This dirty
little secret is a MUCH better earth for your HF radio than anything
screwed under the hull. Even hookup wire will work, but a nice old piece
of stainless winch cable with lots of open strands that won't rust makes
a fantastic trailing-earth ground. Try it with and without....doing a
retune on the tuner as it WILL change the feedpoint impedance of your HF
antenna quite drastically, once connected.

No big $$$ outlay is necessary....just an old piece of stainless cable,
tied off to a sturdy handrail post or the base of the backstay below the
bottom insulator is fine. Don't worry about it sinking. If it were
100' STRAIGHT DOWN, which it won't be unless you're becalmed, that would
be BEST! It doesn't need a dragging anchor to attract the really big
fish, either. If you like, you can just trail it out when making HF
calls, then coil it back in to store it. Works great...

Larry W4CSC

Larry,

I'll bet it does work great. I studied field
theory in engineering school, but I wouldn't have
thought of this without you mentioning it.

Now if I can only remember this when I need it ;-)

Also, it'd sure be great if lightning grounds were
this simple... But unfortunately...

Don W.

Don W wrote in
. net:

Larry wrote:

snip
Now, you can, while you're at sea traveling ahead and not backing
over it, create a pseudo copy of this earth with a single wire hooked
straight to the tuner's ground post, thrown directly overboard to
trail out in the ocean behind the boat...straight as you can get it.
The longer the better, but a good length is from 15-35 meters long.
DON'T forget to roll it up as you come into port so it fouls rudder
or screw! This dirty little secret is a MUCH better earth for your
HF radio than anything screwed under the hull. Even hookup wire will
work, but a nice old piece of stainless winch cable with lots of open
strands that won't rust makes a fantastic trailing-earth ground. Try
it with and without....doing a retune on the tuner as it WILL change
the feedpoint impedance of your HF antenna quite drastically, once
connected.

No big $$$ outlay is necessary....just an old piece of stainless
cable, tied off to a sturdy handrail post or the base of the backstay
below the bottom insulator is fine. Don't worry about it sinking.
If it were 100' STRAIGHT DOWN, which it won't be unless you're
becalmed, that would be BEST! It doesn't need a dragging anchor to
attract the really big fish, either. If you like, you can just trail
it out when making HF calls, then coil it back in to store it. Works
great...

Larry W4CSC

Larry,

I'll bet it does work great. I studied field
theory in engineering school, but I wouldn't have
thought of this without you mentioning it.

Now if I can only remember this when I need it ;-)

Also, it'd sure be great if lightning grounds were
this simple... But unfortunately...

Don W.



When you're at the dock or anchored out, drop a small anchor with the
ground wire attached off the back of the boat overboard, but not touching
bottom so it will follow you around as the boat swings around. My anchor
is a beer can filled with sand. This holds the OTHER half of your
massive dipole vertically in the perfect groundwater for great HF
comms....

PLEASE put a tag on the engine controls to remind you the HF ground is
overboard before starting the engine and blaming me for the fouled prop
backing down...thanks.


Larry
--

Don W wrote in news:vMwXh.19209
:

Also, it'd sure be great if lightning grounds were
this simple... But unfortunately...



Actually, they ARE that simple. Trail two more ground cables, during the
storms, attached to the port and starboard shrouds to trail off electrons
to the sea, right where it's SO easy to attach them at the
deck/chainplates. Don't be neat...use hefty stainless winch cable,
stranded gets the best ground. Find something to stow them in at the
base of the shrouds when not in lightning storms. Great grounds are easy
in the ocean....that don't HAVE to be through a hole in that leaky hull!

Just let the cable trail back on either side in the wake. It only
matters that they are submerged, not skipping along the surface. On our
ketch, at 6 knots, skipping along the surface would be a miracle...(c;

Larry
--

On Thu, 26 Apr 2007 00:14:18 +0000, Larry wrote:


Larry,
A few questions from a dummy in this area.

What diameter should I make the floating ground for the aerial (4mm ?)

I did try trailing a chain and weight on the end of a cable from the
base of the port shroud as alightning ground but the damn thing was
bumping annoyingly against the hull. My back stay is split at the
masthead - one is the aerial for SSB and the other is entire. Could I
attach a cable to that and throwm it ovewr the stern? - or would two
attached to the capshrouds give better protection? I unashamdely admit
to being terrified of being struck again - not a personal fear but one
of having to shell out all those dollars again to replace it all.

I got sick of pulling all the plugs out from the instruments when
lightning hove in the distance - in our path, so I put the 13 wires to
the radar unit for example to a 15 pin plug that just pulls apart -
other instruments likewise. N o more hiolding a colured Visio
schematic and trying to figure colours in the dark.

I should have shaved my arms before antifouling - I am still picking
it off despite cleaning up and showering.

cheers
Peter
Don W wrote in news:vMwXh.19209
:

Also, it'd sure be great if lightning grounds were
this simple... But unfortunately...



Actually, they ARE that simple. Trail two more ground cables, during the
storms, attached to the port and starboard shrouds to trail off electrons
to the sea, right where it's SO easy to attach them at the
deck/chainplates. Don't be neat...use hefty stainless winch cable,
stranded gets the best ground. Find something to stow them in at the
base of the shrouds when not in lightning storms. Great grounds are easy
in the ocean....that don't HAVE to be through a hole in that leaky hull!

Just let the cable trail back on either side in the wake. It only
matters that they are submerged, not skipping along the surface. On our
ketch, at 6 knots, skipping along the surface would be a miracle...(c;

Larry

On Thu, 26 Apr 2007 21:04:02 -0400, Peter Hendra
wrote:

On Thu, 26 Apr 2007 00:14:18 +0000, Larry wrote:


Oh, and what is an optimum length and diameter - covered in plastic or
bare? - I know, only a project manager would want precision such as
this.

Thanks for all of this Larry. I shall follow your advice.

By the way, I have been dutifully hoarding my softdrink/soda/pop
plastic bottles. I even have a large hanging laundry bag to store them
in after rinsing them. However, my favourite drinks here in Trinidad
are Lemon, Lime and Bitters sold by the Angostura company in small
glass bottles and cans of coconut and pineapple fizzy drink. Are you
aware of any techiques whereby I can put out "message in a can" or
"message in a small glass green bottle"? I have been drinking Coca
Cola but no longer wish to support that icon of American Imperialism
(openly at least). We called in to Assab a few years back, the large
and empty Eritrean port that had been captured back from the invading
Ethiopians. At the time, Eritrea was the second poorest nation and had
just won a war of independence against colonising Ethiopia with no
external aid despite both the US and Ruissians suppling their foes
with weapons at different times. The town had nothing but a single
main unpaved street, and apart from the port wharves and cranes was
largely unchanged since the Italians colonised it after the Great War.
There were a lot of little cafes making great, strong and flavoursome
(eat your heart out Vic) espresso coffee with beautifully maintained
polished brass and copper machines dating back to the 1920's. The only
other non-alcoholic drink was good old Coca-Cola kept cool with ice.
Expectedly, both tasted divine.

I only ask about the cans as I recognise the spirit of a lateral
thinking mind and you are wholely responsible for my collection
fetish/mania. I almost ate a half eaten hamburger from a rubbish bin
the other day - it looked delicious but some people I knew were
looking. Still, as my Zoology professor said - "The good germs fight
the bad germs and the good germs usually win".

Waiting for it...............
cheers
Peter the dumpster man


Larry,
A few questions from a dummy in this area.

What diameter should I make the floating ground for the aerial (4mm ?)

I did try trailing a chain and weight on the end of a cable from the
base of the port shroud as alightning ground but the damn thing was
bumping annoyingly against the hull. My back stay is split at the
masthead - one is the aerial for SSB and the other is entire. Could I
attach a cable to that and throwm it ovewr the stern? - or would two
attached to the capshrouds give better protection? I unashamdely admit
to being terrified of being struck again - not a personal fear but one
of having to shell out all those dollars again to replace it all.

I got sick of pulling all the plugs out from the instruments when
lightning hove in the distance - in our path, so I put the 13 wires to
the radar unit for example to a 15 pin plug that just pulls apart -
other instruments likewise. N o more hiolding a colured Visio
schematic and trying to figure colours in the dark.

I should have shaved my arms before antifouling - I am still picking
it off despite cleaning up and showering.

cheers
Peter
Don W wrote in news:vMwXh.19209
:

Also, it'd sure be great if lightning grounds were
this simple... But unfortunately...



Actually, they ARE that simple. Trail two more ground cables, during the
storms, attached to the port and starboard shrouds to trail off electrons
to the sea, right where it's SO easy to attach them at the
deck/chainplates. Don't be neat...use hefty stainless winch cable,
stranded gets the best ground. Find something to stow them in at the
base of the shrouds when not in lightning storms. Great grounds are easy
in the ocean....that don't HAVE to be through a hole in that leaky hull!

Just let the cable trail back on either side in the wake. It only
matters that they are submerged, not skipping along the surface. On our
ketch, at 6 knots, skipping along the surface would be a miracle...(c;

Larry

Peter Hendra wrote in
:

Could I
attach a cable to that and throwm it ovewr the stern? - or would two
attached to the capshrouds give better protection? I unashamdely admit
to being terrified of being struck again - not a personal fear but one
of having to shell out all those dollars again to replace it all.


Yes, that should work fine as a good static discharge if the solid
backstay is electrically attached to the metal mast. The more paths you
provide to seawater ground from that mast....smooth paths with no hard
angles just to make it look "neat", whatever that means....the better.

There is no such thing as "lightning protection". There is surge
protection and static discharge. Static discharge helps prevent
lightning strikes on anything. The static radiating off things is what
makes the path for the "main bang", hundreds of millions of amps at
hundreds of millions of volts nothing can possibly stop.

If your boat is directly hit by a massive lightning strike, it will be
destroyed, not an issue. However, oddly, not many direct hits happen.
What does happen is static discharges from nearby hits and St Elmo's
Fire, the buildup of static on the rigging not bled off. These
discharges, say from the base of an ungrounded mast, will hole the hull
in a hundred places...sinking the boat.

One of my friends was senior engineer for Dialpage in Charleston. I had
a packet 2 meter ham radio digital station on one of Dailpage's towers,
serving the ham community with packet radio for years.

This tower had 3 candelabra-mounted paging antennas at 330 ft AGL and a
very nice grounding system to bleed off the static charge, done the best
way possible to protect the expensive paging transmitters.

It took a direct hit. The top 8 ft of the tower, along with the entire
candelabra antenna system, SIMPLY VANISHED. Not a trace of it was found
on the ground. The stroke mostly ignored the extensive, professionally-
installed ground system after the stroke turned bridge cables into molten
bits of metal, all the way to bedrock under the tower. After those first
few microseconds, now with no ground system, the stroke entered the
transmitter building, which also had a very extensive, professionally-
installed grounding system to protect everything in the building. Bus
bars that were 1/2" thick copper by 2" wide straps were melted, ripped
out of their mounting brackets by the intense magnetic pulse (EMP) the
stroke caused. Every piece of paging equipment, tower lighting
equipment, emergency and AC power panels, even the big diesel genset
outside on its pad, were utterly destroyed. The huge power cables that
came from the building to the power pole outside were "stretched" by the
current blast that blew the transformers (3 phases) off the pole and
drooped these heavy cables to within a foot of the road they crossed
over.

A boater stands NO chance against such a stroke. Glad it doesn't happen
often, but I cannot imagine why.

WJBF-TV/FM in Augusta, GA, was similarly destroyed by a direct hit a long
time ago. The stroke destroyed the telephone system around the tower
over a diameter of over 4 miles! JBF is Channel 6. A few miles away is
Channel 12's tower...the OTHER part of the path! The stroke hit them
both in a big, grounded loop, simultaneously. One of my old broadcast
buddies, who was the duty engineer at JBF at the time, weighted in around
400 pounds. It blew him right off his chair at the console! The stroke
came out the front panel of the FM transmitter and hit the console he was
sitting at! He came to in time to help put out the fires and get out of
the building. They were off the air for months replacing it
all...melted.

Larry
--
Lightning scares the crap out of me, sitting there in the cockpit at the
base of the big lightning rods, holding onto the metal wheel hooked to
the metal GROUNDED rudder hanging out in the sea, below.....