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stan
 
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Default marine ssb antenna

I was recently shown a copy of an article from one of the sailing
magazines (either Blue Water Sailing or Ocean Navigator) in which they
extolled the virtues of quarter wave antennae for marine ssb radios.
The article made two points: 1. No copper ground was needed and 2. the
antennae, cut in appropriate lengths for each wavelength used, could be
connected the antenna automatic tuner, wrapped around a box and the box
thrown into a cockpit locker with no external aerial whatsoever.

The article indicated that this was an idea from the ARRL manual and a
perfectly acceptable alternative to the usual insulated backstay wire
used on all of the boats I'm aware of which have a SSB radio on board.

The question to this group is whether this is a valid alternative to
the usual copper ground & external antenna setup? What are the
advantages (other than cost and ease of installaton) and the
disadvantages?

Thsnks,

Stan

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chuck
 
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Hello Stan,

I don't fully understand the second point. If you really mean no antenna
external to a cockpit locker, then it is either a joke or a
misunderstanding. Perhaps the idea was that the antennas could be rolled
up and kept in a locker when not in use?

A copper ground is not useful with a balanced antenna, such as a dipole
or loop. If these antennas are cut for a specific frequency, then an
antenna tuner may not even be required.

Chuck

stan wrote:
I was recently shown a copy of an article from one of the sailing
magazines (either Blue Water Sailing or Ocean Navigator) in which they
extolled the virtues of quarter wave antennae for marine ssb radios.
The article made two points: 1. No copper ground was needed and 2. the
antennae, cut in appropriate lengths for each wavelength used, could be
connected the antenna automatic tuner, wrapped around a box and the box
thrown into a cockpit locker with no external aerial whatsoever.

The article indicated that this was an idea from the ARRL manual and a
perfectly acceptable alternative to the usual insulated backstay wire
used on all of the boats I'm aware of which have a SSB radio on board.

The question to this group is whether this is a valid alternative to
the usual copper ground & external antenna setup? What are the
advantages (other than cost and ease of installaton) and the
disadvantages?

Thsnks,

Stan

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Larry
 
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"stan" wrote in
oups.com:

No copper ground was needed


This antenna would be a HALFwave, not a quarter wave. The simple dipole
comes to mind. You'd have to have a separate dipole, or end-fed halfwave,
for each marine band...2, 4, 6, 8, 12, 16..etc. Not very practical on a
small sailboat. The formula for finding the length of this dipole or end-
fed halfwave is L = 468/F in Megahertz. Divide 468 by 2.182 and you'll get
214.5 FEET. How tall did you say that mast was on the little
Hunter??...(c; We COULD deploy it with a kite or gas-filled large balloon.
I've used huge advertising balloons to deploy large end-fed wires on 160
meter ham band (1.8-2.0 Mhz). Works great if the wind isn't blowing. Navy
used to include both kite and balloons in their AN/MAY-3 Emergency CW/AM
transmitters in the lifeboats way back. They worked fine on such low
powered, hand-cranked, tube-type transmitters.

But, alas, I haven't found it profitable on a 41' ketch.....(sigh)

By the way, the VHF version of the end-fed halfwave is already aboard our
boat atop both main and mizzen. It's the Metz VHF marine antenna. The
impedance matching transformer is in the base the coax plugs into. The
impedance of the end of the halfwave is quite high, so a large turns ratio
is needed to match it to 50 ohms. The Metz works fine with no ground. You
can even hold it in your hands, hanging onto the coax connector.

--
Larry
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stan
 
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I thought it was a joke but the reference to the ARRL handbook lends it
some credibility. In the article, the author took a rectangular piece
of wood and glued 4 dowel rods about 6" long into each corner and
wrapped the various lengths of antenna wire around the 4 rods, tied
them off and connected one end of each to a bus bar. The bus bar was,
in turn, connected to the tuner. He says the whole thing went into a
locker. I look to the experts to tell me wether this is something which
works or not.

Stan

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stan
 
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I thought it was a joke but the reference to the ARRL handbook lends it
some credibility. In the article, the author took a rectangular piece
of wood and glued 4 dowel rods about 6" long into each corner and
wrapped the various lengths of antenna wire around the 4 rods, tied
them off and connected one end of each to a bus bar. The bus bar was,
in turn, connected to the tuner. He says the whole thing went into a
locker. I look to the experts to tell me wether this is something which
works or not.

Stan



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Larry
 
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"stan" wrote in
oups.com:

works or not.


Anything metal is an antenna. They all "work". But, alas, it's how WELL
they work that makes the difference....

The military has an antenna that's a big H they BURY in the sand. It works
quite well, actually. Sand is a rotten conductor, but a fairly good
camoflage.

Still, the best HF antenna is a long, insulated backstay. Lionheart's is
naturally resonant around 8 Mhz. No tuner is necessary. It's too bad I
can't add a center inductor below that frequency to improve her H-field
when the antenna is so short on the lower bands.... Tuned to 12 Mhz, the
backstay is actually 5/8 wave, which gives her a little gain. 5/8 wave VHF
mobile antennas have been used with end-fed matching since Motorola was in
a garage. 3db gain is the result, but I doubt it's anything like that with
all the rigging loading it all down. Sailboat rigging, metal masts, etc.,
all cost you LOTS of signal by absorption so close to the radiating
backstay. Lionheart is worse with the backstay between main and mizzen
aluminum masts with many shrouds.

I have used my own designed HF mobile antenna for 20 years. It uses one or
two loading coils under a fairly large capacitor hat made of 8 spokes of
stainless welding rod about 36" in diameter. This raises the current
up the antenna to create a larger H field most mobile antennas lack. This
antenna, with a good ground, would make a great marine HF antenna on the
stern of a boat. Tuning it is done by moving a tap on its coil(s), which
are easily swapped and added to with 1/4 turn twist-lock devices that lock
all the components together. Two nylon lines to the handrails forward of
the stern would hold it upright in awful weather. It's 15 feet high, just
low enough to go under standard wires and bridges on the highway....same
height as a tractor trailer.

|
|
|
|
|
|
|
| cut down 102" CB whip to limit height to 15'
QUICK CONNECTOR ^
-----------|----------- capacitor hat 36" diam, 8 spokes
| no outside ring
|
| 4 ft stainless rod threaded 3/8-24 male on both ends
|
QUICK CONNECTOR ^
|-|
| |
| | Henry Allen's largest 6" diam #10 coil
|-| (coil #680)
|
|
| 3 ft stainless rod threaded 3/8-24 male both ends
|
- 3/8-24 base mount on trailer hitch
|=| 10T #10 solid copper wound on fiberglass-insulated
ferrite core tapped with banana-jack at each turn.
coax input shield and one end of the coil go to
chassis ground of car. Coax hot and a jumper strap
from the insulated antenna base have banana plugs
on them so they may tap the coil. This broadband
matches the 17 ohm vertical Z to the 50 ohm coax Z.

Henry Allen's coils are on:
http://www.texasbugcatcher.com/cata/tbcspec.htm#6inch
I use a 680 and 480 coils

This antenna is naturally resonant (big coil shorted out by a strap with a
clip all the way from top to bottom) on 14.250 Mhz. The capacitor hat was
trimmed to resonate it on this frequency of my favorite ham band. Tuned
with only the capacitor hat, the antenna SWR is below 1.4:1 from 14.01 to
14.35 Mhz, the entire ham band. No extra tuning is necessary.

To resonate below 14 Mhz, the strap that is hard connected to the bottom of
the coil has a big clip that taps down the coil to add more inductance.
With the whole coil in the circuit, it resonates at 2.8 Mhz. Any frequency
between 2.8 and 14.35 Mhz is simply a tap change. plastic tabs are glued
to the coil with certain frequencies engraved on them, making tuning a
snap. Even on 75 meters, the antenna is 50 Khz bandwidth to 2:1 SWR
points, making stopping the car unnecessary just to move frequency a ways.

The antenna in this configuration will not resonate above 14.25 Mhz. To
use frequencies above, the antenna is disassembled above the coil and at
the other quick connector above the capacitor hat, removing the 4'
stainless rod section and its capacitor hat. The CB whip now plugs into
the top of the coil for the upper end of HF. The shorted out, natural
resonant frequency WITHOUT the 4' section and capacitor hat is 29.0 Mhz
with the big coil again shorted out completely. It's bandwidth is from
27.8 to over 32 Mhz making this how you tune 10 meters, the whole band. To
get the other upper HF bands, the tap is again moved down the coil to a
single tab marking the position of the tap for each whole ham band. No
further adjustment is necessary as the antenna is very broadbanded up here.

An extra coil, Allen #480XL, is added directly to the top of the 6" coil to
increase loading inductance for use on the 1.8-2.0 Mhz ham band only. The
coil is added and the 6" coil's shorting tap is adjusted to tune the
antenna on a 30 Khz bandwidth of this band. This extra coil has quick
connectors on both ends to mate with the quick connectors (symbol ^ on my
graphic) on top of the big coil. Just disconnect the whole top of the
antenna and insert this coil.
An additional base toroid transformer is also swapped out. It has 30
turns, instead of the 10 turns used above 3 Mhz. Input is across all 30
turns. Antenna plugs into turn 8 or 9 to get a perfect match.

I feed this antenna with an honest 650 watts of RF power from a modified
TenTec Hercules II 12V solid-state HF linear amp in the trunk. It is fed
from a pair of 220AH golf cart beasts also trunk mounted and connected
through a marine ON-OFF switch to the old '73 Mercedes 220D's big
alternator and starting battery up front. Same idea as a boat. The house
battery is in the trunk so I can use it without the engine running. It
only draws 120 amps at full power on RTTY, key-down CW. At 300 watts
carrier on AM, it draws a measily 55 amps. SSB average current is much
lower, of course, at 650W PEP. Transceiver is a Yaesu FT-900, trunk
mounted with its removeable control panel on a flexible stick on the dash
right next to the steering wheel. I use a Heil headset/mic and VOX keying
on phone modes. It even runs 600 watts on 10 meter FM...(c; At this power
level, especially on bands below 7 Mhz, a very large corona appears on the
ends of the capacitor hat spokes (even after we bent them around to get rid
of the "points") and at the top of the CB whip. On 160 meters, this corona
trails out behind the antenna at highway speed as we ionize the air. It
flashes over to low interstate bridges! It also lights flourescent signs
within 15 feet of it...right in their boxes...(c; An old KAM Plus and
Win98SE notebook provide digital service. The notebook also serves as the
VHF portable packet station into a Paccomm Tiny II subminiature TNC and
tiny VHF walkie to carry around hamfests talking to DX stations THROUGH the
KAM Plus' crossband packet repeater and the 650 watt mobile HF packet
station left running in the parking lot, unattended. IF YOU SEE IT PARKED
SOMEWHERE, READ THE SIGN ON THE ANTENNA THAT SAYS "DANGER-RF RADIATION
HAZARD" and DON'T TOUCH IT EVEN IF YOU DON'T SEE ME! Many can't
read....fingers burned appropriately...hee hee.

This mostly-home-made antenna would make a great boat antenna for marine
HF, once you learned how its simple tuning is done. Yeah, it's not
pushbutton automatic from the nav station. But, with its amazing signal
and very strong RF field it produces, other stations cannot believe they
are hearing a MOBILE, driving down the interstate...especially on 160
meters where mobiles rarely tread. Many times I've been called a liar,
well, until they hear a truck pass and my horn blow over the air. As it is
always a RESONANT antenna, not some random length wire with a very lossy
base tuner, like your current boat HF antenna, it just simply radiates a
MUCH stronger RF field. It survives 80 mph, about as fast as a 2.2L 4-cyl
diesel will run that's going on 33 years old. I use two monofilament
fishing lines to the two rear doors to "guy" it against the wind from the
top of the big coil. This keeps it from bending back against the 57hp
diesel's lightning acceleration, too!

--
Larry W4CSC

Ok, guys....Unkey the RTTY until Mike gets into the car. His fingers keep
burning on the door handle...(c;

POWER IS OUR FRIEND!

NNNN
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Larry
 
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"stan" wrote in
ups.com:

I look to the experts to tell me wether this is something which
works or not.

Stan


There used to be a CB magazine that always had antenna projects in it.

In the last April Issue, there was a big project called the "Butterfly
Antenna", made out of wire like a coathanger of old, that looked like a
large butterfly...body, wings and all.

In the LAST May issue, the readers were informed of the April Fool's Joke,
the Butterfly Antenna. CBers who had worked all month to build, erect and
spent hours trying to get it to work were NOT amused! By September, the
magazine was discontinued, never to be heard from again.....I forget its
name....(c;

The word BLUNDER comes to mind.....

--
Larry

Little antennas have little signals.....Big antennas have big signals....
It's why 50 KW AM radio stations have huge multi-tower arrays, not hidden
antennas in a desk....


......which SUCK!
  #8   Report Post  
Terry
 
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"stan" wrote in message
oups.com...
I thought it was a joke but the reference to the ARRL handbook lends it
some credibility. In the article, the author took a rectangular piece
of wood and glued 4 dowel rods about 6" long into each corner and
wrapped the various lengths of antenna wire around the 4 rods, tied
them off and connected one end of each to a bus bar. The bus bar was,
in turn, connected to the tuner. He says the whole thing went into a
locker. I look to the experts to tell me wether this is something which
works or not.

Stan

I gather there are a lot of myths about radio antennae.

The fact seems to be that if you can effectively 'couple' the radio energy
from your transmitter to any (metal) object it will radiate the signal no
matter how inefficiently.

For example I talked to a radio amateur who uses his metallic cored clothes
line as an antenna! Fortunately he was/is on a hill in Scotland.

I also recall the Order Of Canada Radio/TV pioneer, Oscar Hierlihy, who
explained to me how he had managed to use the metal roof of his car, without
detaching or altering it in any way, as an amateur radio antenna and had
made some local contacts (QSOs) from his car without using any other
antenna!

In civil jurisdictions that 'do not allow external radio antenna/towers'
stories abound about coupling to metal gutters and downspouts, metal curtain
rods, metal air conditioning ducts or to metal flag poles and/or to wires
hidden on the surface of a wooden fence posts etc. One person claimed he
used the corrugated iron roof of his garden shed as a receiving and
transmitting antenna!

In other words almost anything can be made to 'radiate' (and by inference
thereby also 'receive') a radio signal. But how well a wrapped up bunch of
wires stuffed into a damp locker, low down to the water line will work
compared to a well insulated and properly coupled, antenna in the clear, as
far as is possible on a boat with wire rigging, would be unknown.

IMO it would be rather like putting kerosene instead of high grade gasoline,
into your sports car and with the engine sputtering and bucking and able
only to achieve one quarter top speed, saying, "See it works"! And so it
may, but not well.


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Bruce in Alaska
 
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In article . com,
"stan" wrote:

I thought it was a joke but the reference to the ARRL handbook lends it
some credibility. In the article, the author took a rectangular piece
of wood and glued 4 dowel rods about 6" long into each corner and
wrapped the various lengths of antenna wire around the 4 rods, tied
them off and connected one end of each to a bus bar. The bus bar was,
in turn, connected to the tuner. He says the whole thing went into a
locker. I look to the experts to tell me wether this is something which
works or not.

Stan


What your discribing is a "Tuned Counterpoise", and is what would
replace the "copper ground" for the autotuner. There are a "few"
problems with this approch to Marine MF/HF Antenna designs.

First, the "Tuned Counterpoise" has a very narrow Bandwidth, which is OK
for some HF Marine applications where only one or two channels are
available for use, in each band, but as a general coverage antenna,
"they Suck, Bigtime".
Second, Because of the "High Q" nature of this system, any frequency
movement off higher or lower than the counterpoise is tuned for will
GREATLY degrade the preformance of thew antenna system.
Third, the lower the frequency of this type of system the narrower the
bandwidth will be. At MF Frequencies the difference between 2182Khz
and 2638Khz would completely detune the counterpoise effect, and
radically reduce the efficency of the system.

Basically, the theory is very iffy, and the practicality of such a
system is very poor, when compared with more conventional Marine
MF/HF Antenna Systems. It is pure "Hookum"


Bruce in alaska who has seen such "Hookum" in action many times...
--
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