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Roger
 
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Default SSB antenna

I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.
  #2   Report Post  
Terry Spragg
 
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Default SSB antenna

Roger wrote:

I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.


The length of your boat and backstay might help us, here for the
number crunchers.

Test Receiver (Rx) side first, manually adjusting tuner with power
off. Rx adjustments will be similar, reflecting Transmit (Tx) potential.

Consider not insulating your backstay. Just disconnect it's ground /
bonding at the transom. Insulate it with hose to transmit. Feed
point by hanging coax centre only to the midpoint of the split, or
insulate one leg of split from the centre or base and feed the other
bottom. Leave coax shield unconnected at Antenna feed point.
Experiment with directivity and relative sensitivity by monitoring a
distant transmitter while you power in a circle, or adjust matching.

You might be able to tune some by shortening the coax shield and /
or connecting the shield end at the maching box or transmitter by
switching R.F. capacitors in series with the shield, or
disconnecting the shield from ground and connecting it to Tx ground,
chassis or power lead ground. It is generally not good to use DC
wiring as part of the Antenna Counterpoise, but sometimes it will
work a miracle. Consequential lightning or static damage can occur,
frying other stuff. Methods abound.

This method of grounding can be like connecting a welder /
commercial electroplater to your prop and zincs, etc. unless they
are isolated, insulated from ground bonding and R.F. sources. R.F.
capacitor bondings can also be cobbled to lifelines, etc, sometimes
to good effect.

At R.F. distances from the ground connection, ground or power return
wires can become energised WRT other elements, acting as
counterbalancing antenna elements. Here, the more the better, except
for errant pedestrians.

Antennae are like cat's wiskers, sensing the wind is easier with
differential signal sensitivity, like hearing sonar returns through
multi-mike differential time delay systems, steering the sense of
hearing.

Some bondings are to be avoided. Polarisation can also be fiddled,
with goniometer tech and time delay devices.

Understanding R.F. and ground / counterpoise / lightning plans is a
heated subject, hereabouts.

Much fun to watch.

Terry K

  #3   Report Post  
Terry Spragg
 
Posts: n/a
Default SSB antenna

Roger wrote:

I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.


The length of your boat and backstay might help us, here for the
number crunchers.

Test Receiver (Rx) side first, manually adjusting tuner with power
off. Rx adjustments will be similar, reflecting Transmit (Tx) potential.

Consider not insulating your backstay. Just disconnect it's ground /
bonding at the transom. Insulate it with hose to transmit. Feed
point by hanging coax centre only to the midpoint of the split, or
insulate one leg of split from the centre or base and feed the other
bottom. Leave coax shield unconnected at Antenna feed point.
Experiment with directivity and relative sensitivity by monitoring a
distant transmitter while you power in a circle, or adjust matching.

You might be able to tune some by shortening the coax shield and /
or connecting the shield end at the maching box or transmitter by
switching R.F. capacitors in series with the shield, or
disconnecting the shield from ground and connecting it to Tx ground,
chassis or power lead ground. It is generally not good to use DC
wiring as part of the Antenna Counterpoise, but sometimes it will
work a miracle. Consequential lightning or static damage can occur,
frying other stuff. Methods abound.

This method of grounding can be like connecting a welder /
commercial electroplater to your prop and zincs, etc. unless they
are isolated, insulated from ground bonding and R.F. sources. R.F.
capacitor bondings can also be cobbled to lifelines, etc, sometimes
to good effect.

At R.F. distances from the ground connection, ground or power return
wires can become energised WRT other elements, acting as
counterbalancing antenna elements. Here, the more the better, except
for errant pedestrians.

Antennae are like cat's wiskers, sensing the wind is easier with
differential signal sensitivity, like hearing sonar returns through
multi-mike differential time delay systems, steering the sense of
hearing.

Some bondings are to be avoided. Polarisation can also be fiddled,
with goniometer tech and time delay devices.

Understanding R.F. and ground / counterpoise / lightning plans is a
heated subject, hereabouts.

Much fun to watch.

Terry K

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Doug Dotson
 
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Default SSB antenna

Roger,

We have the 23' whip and it works great. Also have a split
backstay, but since the whip was on the boat when we bought
it, I decided to stick with it. I'm not familiar with the 17' whip
you mention. It would appear to me that you may not be
abot to get good tuning acrosss the bands. The specs for the
tuner say that a 23' minimum length is required if I recall
correctly.

Doug, k3qt
s/v Callista

"Roger" wrote in message
om...
I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.



  #5   Report Post  
Doug Dotson
 
Posts: n/a
Default SSB antenna

Roger,

We have the 23' whip and it works great. Also have a split
backstay, but since the whip was on the boat when we bought
it, I decided to stick with it. I'm not familiar with the 17' whip
you mention. It would appear to me that you may not be
abot to get good tuning acrosss the bands. The specs for the
tuner say that a 23' minimum length is required if I recall
correctly.

Doug, k3qt
s/v Callista

"Roger" wrote in message
om...
I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.





  #6   Report Post  
Larry W4CSC
 
Posts: n/a
Default SSB antenna

(Roger) wrote in
om:

I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.


In any HF radio installation, the closer the antenna is to resonance (1/4
wavelength long or 1/2 wavelength long) at the desired operating frequency,
and the further it is located in the clear from CONDUCTIVE surfaces, the
better it operates. 1/4 wavelength, in feet, is 234/frequency in
megahertz. 234/8 Mhz = 29.25 ft. So, the 23' antenna at 8 Mhz requires
less loading coil than the shorter one. quarter wavelength, or shorter,
radiators require a good ground system to operate properly as that creates
an "image antenna", in a boat underwater, to make a half wave dipole.

Marine radio HF uses 2, 4, 6, 8, 12 and 18 Mhz, mostly the 4-8 Mhz
frequency bands at night and 8 to 12 Mhz bands in the daytime is best.
It's easy to get either whip to radiate on 12 or 18 Mhz. As of this
particular period, you'll find few signals on 18 Mhz. Our ham 21 Mhz band
has been dead, really dead, for weeks.

So, the longer the whip, the better on these lower bands.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.

"Lionheart" has a 50+ ft long insulated backstay length to the insulator
near the mainmast. She had a very nasty problem as the boom's lifting was
a stainless steel cable, grounded to the mast, which just sucked away the
RF signal any time the boom was anywhere near centerlined. Replacing the
steel cable with nylon eliminated this problem and still holds up the boom
quite nicely. At 50 ft long, the resonant 1/4 wave freq of the backstay is
around 4.6 Mhz, making her have great signals from that frequency up and a
very respectible signal even in the 2 Mhz band when she has lots of loading
coil inline (the tuner). This length of antenna is near 1/2 wavelength on
the 8 Mhz band. A 1/2 wavelength antenna, end fed at the bottom by a good
tuner, requires no ground at all to "get out" well. (The Metz VHF antenna,
for instance, is an end-fed 1/2 wave on 156 Mhz Marine VHF. It requires no
ground at all.) I sat at E-dock at Ashley Marina in Charleston, SC, and
talked to Hawaii, Australia, Japan and New Zealand on the 14 Mhz ham band.

Is the backstay grounded at the bottom end where it attaches to the
fiberglass? Most aren't. So, you only need one insulator, about 2' from
the top of the backstay to form the antenna. To feed the split
configuration, which is fantastic for a wideband antenna, put the tuner
between the two splits at the bottom, and run two, equal-length wires from
the tuner's high voltage output antenna terminal to the bottom end of both
port and starboard mountings. A good grounding strap to the battery
negative terminal the shortest path possible, completes the installation.
The longer backstay will easily outperform the short whips on the lower
frequency bands. Another great improvement when you are cruising is to
keep 100' of small cable attached to the ground terminal of the tuner.
Throw this cable off the stern with a small drag on its open end to make it
lay out in the sea behind the boat. This makes an AMAZING RF ground! Just
don't forget to coil the cable back up before entering any port and backing
into it under power. 100' of 1/4" or smaller stainless wire or
"copperweld" antenna wire that won't corrode is great. Tie the wire to any
handy handrail post or other tie point then run a slack wire to the ground
terminal on the tuner. Retune every time you change from trailing wire
ground to no-trailing-wire-ground condition as the impedance of the antenna
system changes a lot with changes in grounding condition. It's always a
good idea to push the tune button, even if the Icom is a happy camper....

Larry W4CSC
S/V "Lionheart"
Amel 41 ketch
WDB6254
MMSI 366920680

PS - you only get TWO chances to put the MMSI into the Icom. Follow the
instructions in the manual very carefully....
Call us on DSC HF...We'll do lunch!...(c;


  #7   Report Post  
Larry W4CSC
 
Posts: n/a
Default SSB antenna

(Roger) wrote in
om:

I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.


In any HF radio installation, the closer the antenna is to resonance (1/4
wavelength long or 1/2 wavelength long) at the desired operating frequency,
and the further it is located in the clear from CONDUCTIVE surfaces, the
better it operates. 1/4 wavelength, in feet, is 234/frequency in
megahertz. 234/8 Mhz = 29.25 ft. So, the 23' antenna at 8 Mhz requires
less loading coil than the shorter one. quarter wavelength, or shorter,
radiators require a good ground system to operate properly as that creates
an "image antenna", in a boat underwater, to make a half wave dipole.

Marine radio HF uses 2, 4, 6, 8, 12 and 18 Mhz, mostly the 4-8 Mhz
frequency bands at night and 8 to 12 Mhz bands in the daytime is best.
It's easy to get either whip to radiate on 12 or 18 Mhz. As of this
particular period, you'll find few signals on 18 Mhz. Our ham 21 Mhz band
has been dead, really dead, for weeks.

So, the longer the whip, the better on these lower bands.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.

"Lionheart" has a 50+ ft long insulated backstay length to the insulator
near the mainmast. She had a very nasty problem as the boom's lifting was
a stainless steel cable, grounded to the mast, which just sucked away the
RF signal any time the boom was anywhere near centerlined. Replacing the
steel cable with nylon eliminated this problem and still holds up the boom
quite nicely. At 50 ft long, the resonant 1/4 wave freq of the backstay is
around 4.6 Mhz, making her have great signals from that frequency up and a
very respectible signal even in the 2 Mhz band when she has lots of loading
coil inline (the tuner). This length of antenna is near 1/2 wavelength on
the 8 Mhz band. A 1/2 wavelength antenna, end fed at the bottom by a good
tuner, requires no ground at all to "get out" well. (The Metz VHF antenna,
for instance, is an end-fed 1/2 wave on 156 Mhz Marine VHF. It requires no
ground at all.) I sat at E-dock at Ashley Marina in Charleston, SC, and
talked to Hawaii, Australia, Japan and New Zealand on the 14 Mhz ham band.

Is the backstay grounded at the bottom end where it attaches to the
fiberglass? Most aren't. So, you only need one insulator, about 2' from
the top of the backstay to form the antenna. To feed the split
configuration, which is fantastic for a wideband antenna, put the tuner
between the two splits at the bottom, and run two, equal-length wires from
the tuner's high voltage output antenna terminal to the bottom end of both
port and starboard mountings. A good grounding strap to the battery
negative terminal the shortest path possible, completes the installation.
The longer backstay will easily outperform the short whips on the lower
frequency bands. Another great improvement when you are cruising is to
keep 100' of small cable attached to the ground terminal of the tuner.
Throw this cable off the stern with a small drag on its open end to make it
lay out in the sea behind the boat. This makes an AMAZING RF ground! Just
don't forget to coil the cable back up before entering any port and backing
into it under power. 100' of 1/4" or smaller stainless wire or
"copperweld" antenna wire that won't corrode is great. Tie the wire to any
handy handrail post or other tie point then run a slack wire to the ground
terminal on the tuner. Retune every time you change from trailing wire
ground to no-trailing-wire-ground condition as the impedance of the antenna
system changes a lot with changes in grounding condition. It's always a
good idea to push the tune button, even if the Icom is a happy camper....

Larry W4CSC
S/V "Lionheart"
Amel 41 ketch
WDB6254
MMSI 366920680

PS - you only get TWO chances to put the MMSI into the Icom. Follow the
instructions in the manual very carefully....
Call us on DSC HF...We'll do lunch!...(c;


  #8   Report Post  
bruce
 
Posts: n/a
Default SSB antenna

thanks for a very informative post, i've often wondered about using the
copper plate i use for a lightning ground as an rf ground. but tell me,
with the long wire, do you catch any fish?
ok, no hook, do the birds leave it alone?

cheers
bruce


On Fri, 23 Apr 2004 05:06:19 +0000, Larry W4CSC wrote in part:

Another great improvement when you are cruising is to
keep 100' of small cable attached to the ground terminal of the tuner.
Throw this cable off the stern with a small drag on its open end to make
it lay out in the sea behind the boat. This makes an AMAZING RF ground!
Just don't forget to coil the cable back up before entering any port and


  #9   Report Post  
bruce
 
Posts: n/a
Default SSB antenna

thanks for a very informative post, i've often wondered about using the
copper plate i use for a lightning ground as an rf ground. but tell me,
with the long wire, do you catch any fish?
ok, no hook, do the birds leave it alone?

cheers
bruce


On Fri, 23 Apr 2004 05:06:19 +0000, Larry W4CSC wrote in part:

Another great improvement when you are cruising is to
keep 100' of small cable attached to the ground terminal of the tuner.
Throw this cable off the stern with a small drag on its open end to make
it lay out in the sea behind the boat. This makes an AMAZING RF ground!
Just don't forget to coil the cable back up before entering any port and


  #10   Report Post  
Gary Schafer
 
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Default SSB antenna

On Fri, 23 Apr 2004 05:06:19 -0000, Larry W4CSC
wrote:

In any HF radio installation, the closer the antenna is to resonance (1/4
wavelength long or 1/2 wavelength long) at the desired operating frequency,
and the further it is located in the clear from CONDUCTIVE surfaces, the
better it operates.



Why do you think an antenna operates better if it is resonant?

Regards
Gary
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