SSB Antenna connection
 

Dear Folks,

What is the recommended wire to connect my insulated backstay to my
AT-120 tuner ? I see references to GTO15 for this purpose in American
publications, but no-one here in the UK seems to know what GTO15 is.
Could someone please suggest an equivalent, or at least a description !

Also if the ground connection has to be broad copper strip because RF
won't run down a wire like a conventional dc current, how can the
antenna be wire ? Doesn't RF have to run along the cable to the base of
the antenna and then up the antenna wire itself ? I'm confused !

Thanks for your help.

Steve

SSB Antenna connection
 

As has been mentioned on other posts, GTO15 is basically spark plug wire,
that is, high voltage wire. Looking at mine it seems to have a fairly thick
nylon jacket around the tinned wire core and then a thinner black plastic
outer sheath. I would think you could use high quality spark plug wire,
something with the equivalent of 16 or 22 gauge tinned wire core surrounded
by silicone insulation.
Don't know the answer to your second question.

"Steve (another one)" wrote in message
...
Dear Folks,

What is the recommended wire to connect my insulated backstay to my
AT-120 tuner ? I see references to GTO15 for this purpose in American
publications, but no-one here in the UK seems to know what GTO15 is.
Could someone please suggest an equivalent, or at least a description !

Also if the ground connection has to be broad copper strip because RF
won't run down a wire like a conventional dc current, how can the
antenna be wire ? Doesn't RF have to run along the cable to the base of
the antenna and then up the antenna wire itself ? I'm confused !

Thanks for your help.

Steve

SSB Antenna connection
 

GTO-15 wire's full name is "Gas Tube Sign and Ignition Cable". It's rated
for 15,000 volts and has a stranded copper 14 gauge (4110 circular mils)
core. It is single conductor, not coax. There are 19 very fine strands if
wire, a layer of high voltage insulation, and an outer covering of sunlight
resistant PVC. It's used for the high voltage portion of neon signs and for
oil burner ignition cable. It also happens to work very well for connecting
an antenna tuner to an insulated backstay.

Spark plug wire has a much lighter duty core and is often not sunlight
resistant. Most spark plug wires don't even have a metal wire core. They use
a resistance material to suppress RF noise. The resistance is usually
anywhere from 1000 to 4000 ohms per foot. You wouldn't want to use this for
antenna lead wire.

Ancor Marine Grade Products sells a 25 foot (7.62 meter) spool of GTO-15 as
part number 150102. If your local marine supplier doesn't carry GTO-15 wire
then check with a neon sign supply house.

Rusty O

PS: As to the second part of your question. There have been very long
'discussions' on this group about antennas and grounds. Mostly name calling
and opinions with very few facts. I don't wish to start another one.

SSB Antenna connection
 

PS: As to the second part of your question. There have been very long
'discussions' on this group about antennas and grounds. Mostly name calling
and opinions with very few facts. I don't wish to start another one.

Well I think most of the arguments and name calling revolved around proper
methods to get an "good" RF ground.
I don't think there is much argument that you need foil for the RF ground
and something like GTO15 for the antenna connection. As to why you need 2
inch wide foil for the ground lead when circular wire works for the antenna
connection, I think that is a basic physics question that someone probably
can answer.

It is possible to get spark plug wire with wire core. Racers do not like
the carbon resistance wire and they don't care about noise on their radios.
I would agree that some extra cover over top of the spark plug wire is
probably a good idea although high quality silicone wire is pretty tough.

"Rusty O" wrote in message
ink.net...
GTO-15 wire's full name is "Gas Tube Sign and Ignition Cable". It's rated
for 15,000 volts and has a stranded copper 14 gauge (4110 circular mils)
core. It is single conductor, not coax. There are 19 very fine strands if
wire, a layer of high voltage insulation, and an outer covering of
sunlight
resistant PVC. It's used for the high voltage portion of neon signs and
for
oil burner ignition cable. It also happens to work very well for
connecting
an antenna tuner to an insulated backstay.

Spark plug wire has a much lighter duty core and is often not sunlight
resistant. Most spark plug wires don't even have a metal wire core. They
use
a resistance material to suppress RF noise. The resistance is usually
anywhere from 1000 to 4000 ohms per foot. You wouldn't want to use this
for
antenna lead wire.

Ancor Marine Grade Products sells a 25 foot (7.62 meter) spool of GTO-15
as
part number 150102. If your local marine supplier doesn't carry GTO-15
wire
then check with a neon sign supply house.

Rusty O

PS: As to the second part of your question. There have been very long
'discussions' on this group about antennas and grounds. Mostly name
calling
and opinions with very few facts. I don't wish to start another one.

SSB Antenna connection
 

Make sure that you have the real ignition wire and not the wireless wire
type.

Leanne


"Gordon Wedman" wrote in message
news:jqLsc.17107$SQ2.9150@edtnps89...
As has been mentioned on other posts, GTO15 is basically spark plug wire,
that is, high voltage wire. Looking at mine it seems to have a fairly
thick
nylon jacket around the tinned wire core and then a thinner black plastic
outer sheath. I would think you could use high quality spark plug wire,
something with the equivalent of 16 or 22 gauge tinned wire core
surrounded
by silicone insulation.
Don't know the answer to your second question.

SSB Antenna connection
 

Gordon,

Yes, you can get spark plug wire with a real wire core. These days it's not
very common. Like you say, racers use it to get a higher powered spark to
their engine. However, most non-racer's cars today have electronic ignition
systems that require the use of resistance wires. Replacing these wires with
non-resistance wires may actually damage the ignition system.

Rusty O

SSB Antenna connection
 

In article ,
"Steve (another one)" wrote:

Dear Folks,

What is the recommended wire to connect my insulated backstay to my
AT-120 tuner ? I see references to GTO15 for this purpose in American
publications, but no-one here in the UK seems to know what GTO15 is.
Could someone please suggest an equivalent, or at least a description !

Also if the ground connection has to be broad copper strip because RF
won't run down a wire like a conventional dc current, how can the
antenna be wire ? Doesn't RF have to run along the cable to the base of
the antenna and then up the antenna wire itself ? I'm confused !

Thanks for your help.

Steve


Others have covered the GTO-15 question, very well.

There are a number of reasons that copper strap is used for RF Grounding
in the Maritime Radio Installations. One being, that it is desireable
for the RF Ground to have the lowest possible Impedance at the
transmitted frequency.

Two being, that it is desirable that the surface area of the RF Ground
System be as large as practicable, to maximise coupling to the seawater.

Three being, That RF flows on the surface of the conductor, and more
surface area means lower impedance on the Ground.

The antenna wire isn't supposed to couple into the seawater, but into
the ethos, so it should have the least surface area as can practically
handle the RF Current of the transmitter and be tuned to resonance by
the tuner, and as low of resistance as practicable, so that RF Current
can propagate along it's length.

Bruce in alaska Gary S. can chime in anytime on this.....
--
add a 2 before @

SSB Antenna connection
 

"Steve (another one)" wrote in message
...
Dear Folks,

What is the recommended wire to connect my insulated backstay to my
AT-120 tuner ? I see references to GTO15 for this purpose in American
publications, but no-one here in the UK seems to know what GTO15 is.
Could someone please suggest an equivalent, or at least a description !

Also if the ground connection has to be broad copper strip because RF
won't run down a wire like a conventional dc current, how can the
antenna be wire ? Doesn't RF have to run along the cable to the base of
the antenna and then up the antenna wire itself ? I'm confused !

Thanks for your help.

Steve

Steve, you have asked about two distinctly different forms of connection
that require equally different conductors. Additionally, within your
grounding questions there also are two different issues, addressed below:

1. RF feedline from ATU to antenna.

This should be coaxial cable with dialectric and shielding designed for RF.
Never improvise with something such as spark plug wires.

2.(a) Grounding: RF

This does not have to be wide surface area copper, but doing so will not
hurt, and it will allow the combination-use of the RF ground connection to
serve as a lightning protection ground. RF ground does not require a dc-
connection to ground, and is often designed to use capacitive coupling to
ground for sailing vessels and other marine applications where isolation for
galvanic protection is adviseable.

2. (b) Grounding: Lightning protection

Also does not require a dc-connection to ground, but may not use low valued
capacitors such as would be acceptable for RF ground. Lightning protection
DOES require the widest surface area possible, this provides a lower
impedance path to ground. But your radio and auto-tuner and other equipment
are most importantly bonded to each other, and that may be of any standard
braid, #8 wire, etc. Only the single connection of all your bonded equipment
to ship's ground must be of the highest surface area possible. If more than
one connection from bonded equipment to ground must be made, then each of
those connections should be wide surface area conductors.

Hope this helps,

Jack Painter
Virginia Beach, VA

SSB Antenna connection
 

"Jack Painter" wrote in message
news:SR2tc.76990$pJ1.75446@lakeread02...

1. RF feedline from ATU to antenna.

This should be coaxial cable with dialectric and shielding designed for
RF.

Imagine what 2 meters of coax with a capacity of 200pF ( a "load" of about
200 ohms at 4 MHz) does to a high impedance (several kOhms at 4MHz) antenna
connection: right... almost short circuit it to ground.
NEVER use coax between the ATU and the antenna.

Never improvise with something such as spark plug wires.
GTO15 is not sparkplug wire.

2.(a) Grounding: RF

This does not have to be wide surface area copper,

The ground connection has to be as low impedant as possible. Copper strip
has a lower impedance than copper wire with the same cross-section.

Meindert

SSB Antenna connection
 

"Jack Painter" wrote in message
news:SR2tc.76990$pJ1.75446@lakeread02...
"Steve (another one)" wrote in message
...
1. RF feedline from ATU to antenna.

This should be coaxial cable with dialectric and shielding designed for
RF.
Never improvise with something such as spark plug wires.

2.(a) Grounding: RF

This does not have to be wide surface area copper, but doing so will not
hurt, and it will allow the combination-use of the RF ground connection to
serve as a lightning protection ground. RF ground does not require a dc-
connection to ground, and is often designed to use capacitive coupling to
ground for sailing vessels and other marine applications where isolation
for
galvanic protection is adviseable.


NO NO NO coax from ATU to antenna, even inside a metal ship! Use GTO wire.
In an emergency repair in the Aleutians I used HV cable from a television
flyback transformer to the CRT anode once and it worked until the ship got
back to civilization. I have corrected many poor performing backstay
installations by replacing RG-8, 214, etc coax running from the ATU to the
backstay with GTO. What a difference in receive and transmit performance.

Use the widest copper foil you can find, at least 3" for the RF ground path.
The wider the better! Smaller sizes and round wire is too high impedance for
proper HF RF grounding.

Flat braid may be used is you have to use it, putting more that one flat
braid in parallel usually helps.
Doug K7ABX

SSB Antenna connection
 

Doug wrote:
"Jack Painter" wrote in message
news:SR2tc.76990$pJ1.75446@lakeread02...

"Steve (another one)" wrote in message
...
1. RF feedline from ATU to antenna.

This should be coaxial cable with dialectric and shielding designed for

RF.

Never improvise with something such as spark plug wires.

2.(a) Grounding: RF

This does not have to be wide surface area copper, but doing so will not
hurt, and it will allow the combination-use of the RF ground connection to
serve as a lightning protection ground. RF ground does not require a dc-
connection to ground, and is often designed to use capacitive coupling to
ground for sailing vessels and other marine applications where isolation

for

galvanic protection is adviseable.



NO NO NO coax from ATU to antenna, even inside a metal ship! Use GTO wire.
In an emergency repair in the Aleutians I used HV cable from a television
flyback transformer to the CRT anode once and it worked until the ship got
back to civilization. I have corrected many poor performing backstay
installations by replacing RG-8, 214, etc coax running from the ATU to the
backstay with GTO. What a difference in receive and transmit performance.

Use the widest copper foil you can find, at least 3" for the RF ground path.
The wider the better! Smaller sizes and round wire is too high impedance for
proper HF RF grounding.

Flat braid may be used is you have to use it, putting more that one flat
braid in parallel usually helps.
Doug K7ABX


Thanks for these comments, sorry if was a FAQ, I did search first. I
have since asked the same question of Icom UK and their suggestion was
to use the centre conductor of RG213u - having stripped off the outer
shielding. Someone else told me they cut back the centre conductor of
RG213u and used only the shielding which seems very odd as it would have
little insulation.

Anyway, thanks again, I think I now understand the issues and can
assemble something.

Steve

SSB Antenna connection
 

http://www.shipstore.com/ss/html/ANC/ANC150110.html

"Jack Painter" wrote

What is the recommended wire to connect my insulated backstay to my
AT-120 tuner ? I see references to GTO15 for this purpose in American
publications, but no-one here in the UK seems to know what GTO15 is.

SSB Antenna connection
 

"Meindert Sprang" wrote in message
...
"Jack Painter" wrote in message
news:SR2tc.76990$pJ1.75446@lakeread02...

1. RF feedline from ATU to antenna.

This should be coaxial cable with dialectric and shielding designed for
RF.

Imagine what 2 meters of coax with a capacity of 200pF ( a "load" of about
200 ohms at 4 MHz) does to a high impedance (several kOhms at 4MHz)
antenna
connection: right... almost short circuit it to ground.
NEVER use coax between the ATU and the antenna.

Hi Meindert, I don't understand your reasoning there, sorry. And Doug too,
who referenced a steel ship, which is my reference as well. I have seen
hardline (still 50ohm coax) in shipboard installations using the same Sunair
ATU that I use, connected to the wire HF antennas. It appears (to me) no
different that the ungrounded dipole that I feed with coax from my land
station tuners. I have also fed a longwire with that same tuner/coax
combnation, however the longwire was a grounded antenna, and not simlar to a
insulated backstay of a sailboat.

Best regards,

Jack Painter
Virginia Beach,VA

SSB Antenna connection
 

In article SR2tc.76990$pJ1.75446@lakeread02,
"Jack Painter" wrote:

1. RF feedline from ATU to antenna.

This should be coaxial cable with dialectric and shielding designed for RF.
Never improvise with something such as spark plug wires.


Bzzzt, Wrong answer, would you like to try for what's behind Door No. 3??


Coaxial Cable is the WRONG Stuff to be feeding and EndFeed Longwire
Antennas with, even should you not ground the shield, which would be
disasterous in any case.
What is needed is good old GTO15, which like others have
plainly stated, High Voltage - Super High Isulation Wire. In a pinch
I have used the Center Insulation and Feedwire from RG8 or similar
coax with the shiled and jacket stripped off, but this is still not as
good as GTO15.
Yes there are a bunch of Installers who ran around using Hardline
to feed USCG MF/HF SunAirs Antenna Systems from their AutoTuners a few
years back, but the folks who had to maintain those systems 24/7 up
here in alaska, ripped all that **** out and replaced it with
conventional PhospherBronze Antenna Wire with insulators, when it was
determined that the original installations were STONED DEAF compared to
a one transistor radio.
How do I know this you ask? I was the FCC Resident Field Agent
for Southeastern Alaska, and watched it all happen.


Bruce in alaska
--
add a 2 before @

SSB Antenna connection
 

"Bruce in Alaska" wrote in message
"Jack Painter" wrote:

who referenced a steel ship, which is my reference as well. I have seen
hardline (still 50ohm coax) in shipboard installations using the same
Sunair
ATU that I use, connected to the wire HF antennas. It appears (to me) no
different that the ungrounded dipole that I feed with coax from my land
station tuners. I have also fed a longwire with that same tuner/coax
combnation, however the longwire was a grounded antenna, and not simlar to
a
insulated backstay of a sailboat.

Coaxial Cable is the WRONG Stuff to be feeding and EndFeed Longwire
Antennas with, even should you not ground the shield, which would be
disasterous in any case.
What is needed is good old GTO15, which like others have
plainly stated, High Voltage - Super High Isulation Wire. In a pinch
I have used the Center Insulation and Feedwire from RG8 or similar
coax with the shiled and jacket stripped off, but this is still not as
good as GTO15.
Yes there are a bunch of Installers who ran around using Hardline
to feed USCG MF/HF SunAirs Antenna Systems from their AutoTuners a few
years back, but the folks who had to maintain those systems 24/7 up
here in alaska, ripped all that **** out and replaced it with
conventional PhospherBronze Antenna Wire with insulators, when it was
determined that the original installations were STONED DEAF compared to
a one transistor radio.
How do I know this you ask? I was the FCC Resident Field Agent
for Southeastern Alaska, and watched it all happen.

Bruce, I am asking why there is apparently such difference between feeding
an ungrounded dipole with coax from an ATU (my shore station) and feeding an
insulated (hence ungrounded) backstay from an ATU? I work Alaska bareback
in the summertime with that setup and I just can't understand what GTO-15
does that hardline doesn't. If you could explain or reference a document
that specifies the reasoning I would try to correct my misunderstanding.

Thanks,

Jack Painter
Virginia Beach, Va

SSB Antenna connection
 

Bruce, I am asking why there is apparently such difference between feeding
an ungrounded dipole with coax from an ATU (my shore station) and feeding
an
insulated (hence ungrounded) backstay from an ATU? I work Alaska bareback
in the summertime with that setup and I just can't understand what GTO-15
does that hardline doesn't. If you could explain or reference a document
that specifies the reasoning I would try to correct my misunderstanding.

Thanks,

Jack Painter
Virginia Beach, Va

If I can jump in, the quick answer is that the coax is approximately the
same impedance as the center of your ungrounded dipole, at least at the
frequency for which it is resonant. Thus, from the perspective of the
transmitter and the antenna, the transmission line is "invisible." I'm
exaggerating, of course.

In the case of a backstay used as an antenna, the feedpoint impedance can be
anywhere from a small fraction of an ohm at low frequencies to thousands of
ohms where it approximates a half-wavelength. In those cases, the coax will
most certainly not be invisible and will most likely either burn up or
greatly attenuate your signal (incoming as well as outgoing, actually).

If you tried to end-feed your half-wavelength dipole with coax, you would
see a similar problem because the impedance at the ends is in the thousands
of ohms range.

Hope that helps.

Chuck

SSB Antenna connection
 

"Jack Painter" wrote in message
news:pxstc.52$9h.43@lakeread02...

Hi Meindert, I don't understand your reasoning there, sorry. And Doug
too,
who referenced a steel ship, which is my reference as well. I have seen
hardline (still 50ohm coax) in shipboard installations using the same
Sunair
ATU that I use, connected to the wire HF antennas.

A backstay antenna is relatively short compared to the wavelength. It
therefore has a high impedance. To match it to the 50 ohm of the
transceiver, the impedance has to be transformed by an L-circuit with the
capacitance at the low impedant side to ground and the inductance from the
low impedance "hot" side to the antenna. If you would use coax at the high
impedant antenna side, you get a terrible mismatch. The capacitance of this
pice of coax adds to the L circuit at the wrong side, effectively giving you
a PI circuit which is unable to match the high impedant backstay to the 50
ohms of the transceiver.

It appears (to me) no
different that the ungrounded dipole that I feed with coax from my land
station tuners.

Theoretically no. But your land dipole is probably much longer than a
backstay and therefore has a lower impedance. By the way, does your coax
connect directly to the dipole or do you have a balun (with a possible
impedance transformation wich makes the coax have less influence)?

Meindert

SSB Antenna connection
 

"Meindert Sprang" wrote in message
...
"Jack Painter" wrote in message
news:pxstc.52$9h.43@lakeread02...

Hi Meindert, I don't understand your reasoning there, sorry. And Doug
too,
who referenced a steel ship, which is my reference as well. I have seen
hardline (still 50ohm coax) in shipboard installations using the same
Sunair
ATU that I use, connected to the wire HF antennas.

A backstay antenna is relatively short compared to the wavelength. It
therefore has a high impedance. To match it to the 50 ohm of the
transceiver, the impedance has to be transformed by an L-circuit with the
capacitance at the low impedant side to ground and the inductance from the
low impedance "hot" side to the antenna. If you would use coax at the high
impedant antenna side, you get a terrible mismatch. The capacitance of
this
pice of coax adds to the L circuit at the wrong side, effectively giving
you
a PI circuit which is unable to match the high impedant backstay to the 50
ohms of the transceiver.

It appears (to me) no
different that the ungrounded dipole that I feed with coax from my land
station tuners.

Theoretically no. But your land dipole is probably much longer than a
backstay and therefore has a lower impedance. By the way, does your coax
connect directly to the dipole or do you have a balun (with a possible
impedance transformation wich makes the coax have less influence)?

Meindert,

Thanks very much, that was a lightbulb going off (duh) that the backstay on
less than a 70' yacht is going to have a seriously short antenna WRT
wavelength! My wires and dipole are of course half wave devices and at
desired frequencies do not even require a tuner at all. And yes I do use a
1:1 Balun (isolation only on the tunes dipole, 4:1 on random wires). And
just because the specs of my Sunair Coupler _could_ deal with any wire 30'
or longer, that would be a frivolous effort to try to tune, say 2182khz on
so short a wire with 50ohm coax. It does work mediocre on an 80' wire but I
am still somewhat surprised that any sailing vessel could get much
performance (if any do) on MF from a (relatively short) backstay antenna.
Closer to the 1/2 wavelength, I would think that coax would be more
appropriate to the ATU-to-Antenna match than this GTO-15. Correct? And a 4:1
balun would in other cases make the match even more feasable, as well as the
desirable electrical isolation from noise that a Balun can provide.

73

Jack Painter
Virginia Beach, Va

SSB Antenna connection
 

"Chuck" wrote in message ...
Bruce, I am asking why there is apparently such difference between
feeding
an ungrounded dipole with coax from an ATU (my shore station) and
feeding
an
insulated (hence ungrounded) backstay from an ATU? I work Alaska
bareback
in the summertime with that setup and I just can't understand what
GTO-15
does that hardline doesn't. If you could explain or reference a document
that specifies the reasoning I would try to correct my misunderstanding.

Thanks,

Jack Painter
Virginia Beach, Va

If I can jump in, the quick answer is that the coax is approximately the
same impedance as the center of your ungrounded dipole, at least at the
frequency for which it is resonant. Thus, from the perspective of the
transmitter and the antenna, the transmission line is "invisible." I'm
exaggerating, of course.

In the case of a backstay used as an antenna, the feedpoint impedance can
be
anywhere from a small fraction of an ohm at low frequencies to thousands
of
ohms where it approximates a half-wavelength. In those cases, the coax
will
most certainly not be invisible and will most likely either burn up or
greatly attenuate your signal (incoming as well as outgoing, actually).

If you tried to end-feed your half-wavelength dipole with coax, you would
see a similar problem because the impedance at the ends is in the
thousands
of ohms range.

Hope that helps.

Chuck, as with Meindert's answer, yes that helps, thank you.

I do end-feed a long wire as I said earlier, but it uses a 4:1 Balun, and
additionally, has one side of that Balun shorted to ground. This is a
noise-limiting design, and while the nice folks at Radio Works (Portsmouth,
Va) maintain that it cannot possibly work this way (their Baluns), the CG
aircraft I worked in Ecuador with it thought otherwise. So does it's
designer, whose name slips my mind at the moment but he was a primary
contributer to "Proceedings", and a Phd in EE with many patented antenna
designs. Anyway, it would be interesting to see some modelling done with
backstay antennas using various feedline approaches. I suspect the
difference varies greatly with wavelength, height above ground (water),
angle, and frequency.

73,
Jack Painter
Virginia Beach, Va

SSB Antenna connection
 

On Fri, 28 May 2004 18:58:25 -0400, "Jack Painter" wrote:


good stuff by Meindert snipped

Thanks very much, that was a lightbulb going off (duh) that the backstay on
less than a 70' yacht is going to have a seriously short antenna WRT
wavelength! My wires and dipole are of course half wave devices and at
desired frequencies do not even require a tuner at all. And yes I do use a
1:1 Balun (isolation only on the tunes dipole, 4:1 on random wires). And
just because the specs of my Sunair Coupler _could_ deal with any wire 30'
or longer, that would be a frivolous effort to try to tune, say 2182khz on
so short a wire with 50ohm coax. It does work mediocre on an 80' wire but I
am still somewhat surprised that any sailing vessel could get much
performance (if any do) on MF from a (relatively short) backstay antenna.
Closer to the 1/2 wavelength, I would think that coax would be more
appropriate to the ATU-to-Antenna match than this GTO-15. Correct? And a 4:1
balun would in other cases make the match even more feasable, as well as the
desirable electrical isolation from noise that a Balun can provide.

73

Jack Painter
Virginia Beach, Va


Jack, I too wonder about the matching of (short) backstay HF antennas.
The thing that occurs to me is that trying to match the ATU to the antenna
isn't really the goal. The ATU *IS* the matching network. By feeding the
backstay with a coax, the excess capacitance (due to the coax) is just
another reactance the ATU must try to "tune out". Using coax is equivalent
to conncting shunt capacitors from there to ground.
My opinion is that the lead, whatever it is, between the ATU and the
*real* antenna, becomes part of the antenna. To me it makes sense
to use something like GTO-15 between the ATU and backstay.
We also must remember that matching the ATU to the backstay is only
part of the job. The ATU must present a proper impedance to
the transceiver. If the antenna is a horrible match, and the ATU
runs out of "range", then the impedance presented to the transceiver must
suffer also.
Be nice to put a network analyzer on a backstay and see what it
really looks like, eh? Be an opportunity to experiment with
different grounding schemes also. I'm convinced that salt water
is the best possible ground....coupling/connecting to it is the challange.
My 2-bits worth...
Norm B

SSB Antenna connection
 

"engsol" wrote in message
...
On Fri, 28 May 2004 18:58:25 -0400, "Jack Painter"
wrote:

good stuff by Meindert snipped

Jack, I too wonder about the matching of (short) backstay HF antennas.
The thing that occurs to me is that trying to match the ATU to the antenna
isn't really the goal. The ATU *IS* the matching network. By feeding the
backstay with a coax, the excess capacitance (due to the coax) is just
another reactance the ATU must try to "tune out". Using coax is equivalent
to conncting shunt capacitors from there to ground.
My opinion is that the lead, whatever it is, between the ATU and the
*real* antenna, becomes part of the antenna. To me it makes sense
to use something like GTO-15 between the ATU and backstay.
We also must remember that matching the ATU to the backstay is only
part of the job. The ATU must present a proper impedance to
the transceiver. If the antenna is a horrible match, and the ATU
runs out of "range", then the impedance presented to the transceiver must
suffer also.
Be nice to put a network analyzer on a backstay and see what it
really looks like, eh? Be an opportunity to experiment with
different grounding schemes also. I'm convinced that salt water
is the best possible ground....coupling/connecting to it is the challange.
My 2-bits worth...
Norm B

Hi Norm, I'm still learning to use EZNEC http://www.eznec.com/ modelling
software, but I will ask a friend who works with it often to run some
typical backstay offerings and see how it portrays various configurations.

Best,
Jack Painter
Virginia Beach, Va

SSB Antenna connection
 

In article ulztc.40$Y21.34@lakeread02,
"Jack Painter" wrote:

"Bruce in Alaska" wrote in message
"Jack Painter" wrote:

who referenced a steel ship, which is my reference as well. I have seen
hardline (still 50ohm coax) in shipboard installations using the same
Sunair
ATU that I use, connected to the wire HF antennas. It appears (to me) no
different that the ungrounded dipole that I feed with coax from my land
station tuners. I have also fed a longwire with that same tuner/coax
combnation, however the longwire was a grounded antenna, and not simlar to
a
insulated backstay of a sailboat.

Coaxial Cable is the WRONG Stuff to be feeding and EndFeed Longwire
Antennas with, even should you not ground the shield, which would be
disasterous in any case.
What is needed is good old GTO15, which like others have
plainly stated, High Voltage - Super High Isulation Wire. In a pinch
I have used the Center Insulation and Feedwire from RG8 or similar
coax with the shiled and jacket stripped off, but this is still not as
good as GTO15.
Yes there are a bunch of Installers who ran around using Hardline
to feed USCG MF/HF SunAirs Antenna Systems from their AutoTuners a few
years back, but the folks who had to maintain those systems 24/7 up
here in alaska, ripped all that **** out and replaced it with
conventional PhospherBronze Antenna Wire with insulators, when it was
determined that the original installations were STONED DEAF compared to
a one transistor radio.
How do I know this you ask? I was the FCC Resident Field Agent
for Southeastern Alaska, and watched it all happen.

Bruce, I am asking why there is apparently such difference between feeding
an ungrounded dipole with coax from an ATU (my shore station) and feeding an
insulated (hence ungrounded) backstay from an ATU? I work Alaska bareback
in the summertime with that setup and I just can't understand what GTO-15
does that hardline doesn't. If you could explain or reference a document
that specifies the reasoning I would try to correct my misunderstanding.

Thanks,

Jack Painter
Virginia Beach, Va



The fellow that followed your post did a good job in his reply.
The thing that get most of the rookie marine installers in trouble
is that they think of an antenna and tuner as if it only worked
at one frequency. They design the system for that frequency and think
they have a good system. Well it does work for one frequency but when
they try another band, things go very wrong and things just don't work
anymore. This is exactly why tuned counterpoises are an absolute JOKE
in the Marine Radio Service, but we still see them touted as the
greatest thing since canned beans. A good antenna system for a Marine
Radio Installation needs to be as efficent as possible across the whole
MF/HF Spectrum. Given a Wood or Plastic hull, this is a very daunting
challenge for the worlds best RF Engineer, let alone the SuperHam turned
Instant Expert Marine Radio Installer in a day. What is required is:
1. The Best RF Coupled Ground system one can afford to install onboard.
2. No compromise on the RF Ground System.
3. It is the RF Ground that makes the Radio work.
4. An antenna that is long enough to have a reasonable antenna
effeicency at the lowest frequency that the radio will operate at.
(this means about 75 Ft or more for 2182 Khz)
5. No compromise on the installation because of the wifes astetic
senseabilities. (build it to work, not just look good)
There are more but I think you get the idea. Just because you can
get a signal report on 12 Mhz during the day from the other coast
doesn't mean squat, about how good your Radio system is really doing.
If the band is open a 10watt TX on a dummyload can be heard on the other
coast. What makes a good system is carefully planning the installation
of the RF Ground System and then not compromising the antenna length
because you can't figure out how to install what is needed to make the
system work. All autotuners did for the industry is allow any fool to
install something that looks good, but radiates about as well as a wet
noddle. Back when all the tuners were setup by the installing Tech, he
had to actually make the system work, or he didn't get paid. Now there
is a novel thought.

Ok now I'll get off my soapbox......

Bruce in alaska
--
add a 2 before @

SSB Antenna connection
 

All --

Please comment on the following:

What about using copper tubing as an RF ground connection? Since the
current flows on the surface, a tube seems to be the most space efficient
way to get a large surface area. PI*R seems to say that a 1" copper tube
would be as effective as a 3" or so copper foil.

Any thoughts?

Thanks,
Dave.

"Bruce in Alaska" wrote in message
...
In article ulztc.40$Y21.34@lakeread02,
"Jack Painter" wrote:

"Bruce in Alaska" wrote in message
"Jack Painter" wrote:

Major snippage

SSB Antenna connection
 

Did you ever try to route copper tube through all the nooks and almost
inaccessible places that you have to run the foil in a boat in order to
connect the radio, antenna tuner, and dyna-plate? I can form a coat
hanger to stick through a small crack, tape it to the foil and pull the
foil through the crack. Can you do that with copper tube. Copper tube
may give the same surface area, but installation on most boats would be
a nightmare.
Kelton
s/v Isle Escape

Dave Morschhauser wrote:
All --

Please comment on the following:

What about using copper tubing as an RF ground connection? Since the
current flows on the surface, a tube seems to be the most space efficient
way to get a large surface area. PI*R seems to say that a 1" copper tube
would be as effective as a 3" or so copper foil.

Any thoughts?

Thanks,
Dave.

"Bruce in Alaska" wrote in message
...

In article ulztc.40$Y21.34@lakeread02,
"Jack Painter" wrote:


"Bruce in Alaska" wrote in message

"Jack Painter" wrote:

Major snippage

SSB Antenna connection
 

This addresses a question I thought I saw on this group not long ago. I
apologize for not being able to post this in a timely way. I also apologize
if this information has already been posted.

The question was whether it was necessary to provide an RF ground for the
transmitter in addition to the RF ground provided at the ATU. I believe the
answer is generally no.

First, whether there is any direct connection between the transmitter case
(i.e., the outer shield of the coax connecting the transmitter to the ATU)
and the ground terminal at the output of the ATU is entirely coincidental.
Well, not really coincidental. It would be better to say that such a direct
connection is not required. A good many ATU designs utilize inductive
coupling to the transmitter, or to the antenna, and a direct connection in
those cases is purely optional.

The common marine ATUs, however, rely on a form of L-matching circuit in
which there IS a direct connection between input and output "grounds". And
so the transmitter case winds up being connected directly to the ATU ground
terminal and, therefore, to the vessel's RF ground system, whatever that
might be.

We need to keep in mind that the proper functioning of an antenna, tuner,
transmission line, and transmitter, whether on a boat or off, does not
require as a matter of theory that the transmitter case be connected to RF
ground.

As a practical matter though, the transmitter and the transmission line to
the tuner are both in the very near field of the antenna. This is especially
true on a boat. RF from the antenna can travel along the outer shield of the
coax, along microphone, speaker, and power cables and get back inside the
transmitter with difficult-to-predict consequences!

Getting to the real point, now. So sometimes, we need to do things like run
a copper foil (low impedance) RF ground connection from the transmitter case
to the boat's RF ground system. Sometimes it will help, sometimes it can
make matters worse. Sorry. Also, the system is likely to behave differently
at different frequencies. There are ways to test for these currents and
often ferrites can be used in the lines to choke problem currents.

Finally, caution should be exercised in relying on copper foil to provide
lightning protection. It would vaporize like an old-fashioned fuse with any
significant current flow. It would be fine, however, for draining off charge
accumulations from masts and wire rigging.

Hope this helps.


Chuck

SSB Antenna connection
 

"Jack Painter" wrote in message
news:luPtc.221$Y21.126@lakeread02...
Thanks very much, that was a lightbulb going off (duh) that the backstay
on
less than a 70' yacht is going to have a seriously short antenna WRT
wavelength!

Precisely! :-)

My wires and dipole are of course half wave devices and at
desired frequencies do not even require a tuner at all.

Aha, there's the catch..

And yes I do use a 1:1 Balun (isolation only on the tunes dipole, 4:1 on
random wires). And
just because the specs of my Sunair Coupler _could_ deal with any wire 30'
or longer, that would be a frivolous effort to try to tune, say 2182khz on
so short a wire with 50ohm coax. It does work mediocre on an 80' wire but
I
am still somewhat surprised that any sailing vessel could get much
performance (if any do) on MF from a (relatively short) backstay antenna.

It all depends on proper tuning. Your 4:1 balun might not be enough on short
wires. Try a 9:1 balun. But anyway, it is always betten not to use a low
impedant cable like coax between a tuner and an antenna.
This might explain your wonder about the ability of vessels to get good
performance. At a vessel, the cable run from tuner to antenna is mostly (I
hope :-) ) short and made of GTO15 or similar stuff. If you, on the other
hand, use coax to the antenna, even with a 4:1 balun which is not
transforming high enough, you have a problem tuning it properly.

If you have the chance, try a balun (1:1) directly after the tuner, better
yet, use a symmetrical tuner, and feed a dipole with open line (two wires,
spaced 3" apart). This will give you:
A) better tuneability and B) better surpression of man-made noise. To
prevent the feeders from radiating, you could add a common-mode choke in the
feeder (sometimes called a current-balun).

Closer to the 1/2 wavelength, I would think that coax would be more
appropriate to the ATU-to-Antenna match than this GTO-15. Correct?

Only if you feed the 1/2 in the low impedance point, which is halfway in the
middel. Since this is impractical on a boat, feed it at the endpoint. But at
the endpoint of a 1/2 wave, the impedance is very high so you need the least
capacitance you can get at the antenna feedpoint. So GT15 is ok, but keep it
1" away from any grounded or other conductive area (like strapping the GTO15
to the uninsulated lower part of the backstay with tie-raps... BAD
PRACTICE).

Meindert
PE1GRV

SSB Antenna connection
 

"engsol" wrote in message
...
On Fri, 28 May 2004 18:58:25 -0400, "Jack Painter"
wrote:


good stuff by Meindert snipped

:-)

Jack, I too wonder about the matching of (short) backstay HF antennas.
The thing that occurs to me is that trying to match the ATU to the antenna
isn't really the goal. The ATU *IS* the matching network. By feeding the
backstay with a coax, the excess capacitance (due to the coax) is just
another reactance the ATU must try to "tune out". Using coax is equivalent
to conncting shunt capacitors from there to ground.

Precisely

My opinion is that the lead, whatever it is, between the ATU and the
*real* antenna, becomes part of the antenna.

Indeed, it will radiate as much as the antenna does. Therefore it is best to
place the ATU immediately at the feed point of the backstay. The best
practical place would be directly below deck, underneath the backstay. Every
effort to keep the GTO15 as short as possible is best.

Meindert

SSB Antenna connection
 

"Chuck" wrote in message ...
This addresses a question I thought I saw on this group not long ago. I
apologize for not being able to post this in a timely way. I also
apologize
if this information has already been posted.

The question was whether it was necessary to provide an RF ground for the
transmitter in addition to the RF ground provided at the ATU. I believe
the
answer is generally no.

The best place for grounding is at the ATU. Grounding the TX is not
necessary then. If you only ground the TX, high RF currents will flow on the
outside of the coax from ATU to ground and as a result the coax will radiate
too.

Meindert
PE1GRV

SSB Antenna connection
 

The question was whether it was necessary to provide an RF ground for the
transmitter in addition to the RF ground provided at the ATU. I believe the
answer is generally no.

Well as I mentioned previously, Icom's printed literature on
antenna/transciever installation recommends grounding the transmitter to the
same ground ("boat ground") as the tuner using foil. Of course the Icom
tech that I contacted about this said not to ground the radio so everyone is
confused about this..................

"Chuck" wrote in message ...
This addresses a question I thought I saw on this group not long ago. I
apologize for not being able to post this in a timely way. I also
apologize
if this information has already been posted.

The question was whether it was necessary to provide an RF ground for the
transmitter in addition to the RF ground provided at the ATU. I believe
the
answer is generally no.

First, whether there is any direct connection between the transmitter case
(i.e., the outer shield of the coax connecting the transmitter to the ATU)
and the ground terminal at the output of the ATU is entirely coincidental.
Well, not really coincidental. It would be better to say that such a
direct
connection is not required. A good many ATU designs utilize inductive
coupling to the transmitter, or to the antenna, and a direct connection in
those cases is purely optional.

The common marine ATUs, however, rely on a form of L-matching circuit in
which there IS a direct connection between input and output "grounds". And
so the transmitter case winds up being connected directly to the ATU
ground
terminal and, therefore, to the vessel's RF ground system, whatever that
might be.

We need to keep in mind that the proper functioning of an antenna, tuner,
transmission line, and transmitter, whether on a boat or off, does not
require as a matter of theory that the transmitter case be connected to RF
ground.

As a practical matter though, the transmitter and the transmission line to
the tuner are both in the very near field of the antenna. This is
especially
true on a boat. RF from the antenna can travel along the outer shield of
the
coax, along microphone, speaker, and power cables and get back inside the
transmitter with difficult-to-predict consequences!

Getting to the real point, now. So sometimes, we need to do things like
run
a copper foil (low impedance) RF ground connection from the transmitter
case
to the boat's RF ground system. Sometimes it will help, sometimes it can
make matters worse. Sorry. Also, the system is likely to behave
differently
at different frequencies. There are ways to test for these currents and
often ferrites can be used in the lines to choke problem currents.

Finally, caution should be exercised in relying on copper foil to provide
lightning protection. It would vaporize like an old-fashioned fuse with
any
significant current flow. It would be fine, however, for draining off
charge
accumulations from masts and wire rigging.

Hope this helps.


Chuck

SSB Antenna connection
 

I know that one has to be careful that a suffucuent DC ground is
provided in addition to the RF ground. Otherwise high currents
can be drawn though the RF ground with bad results. I personally
have never heard of no grounding the radio to the RF ground. If
you look at the manual for most any HF rig you will see that it
requires an earth ground to a stud on the back of the rig. Seems
to me that connecting this to the RF counterpoise makes sense.

Doug, k3qt
s/v Callista

"Gordon Wedman" wrote in message
news:mYIuc.10643$ig5.6123@edtnps89...
The question was whether it was necessary to provide an RF ground for the
transmitter in addition to the RF ground provided at the ATU. I believe
the
answer is generally no.

Well as I mentioned previously, Icom's printed literature on
antenna/transciever installation recommends grounding the transmitter to
the
same ground ("boat ground") as the tuner using foil. Of course the Icom
tech that I contacted about this said not to ground the radio so everyone
is
confused about this..................

"Chuck" wrote in message
...
This addresses a question I thought I saw on this group not long ago. I
apologize for not being able to post this in a timely way. I also
apologize
if this information has already been posted.

The question was whether it was necessary to provide an RF ground for
the
transmitter in addition to the RF ground provided at the ATU. I believe
the
answer is generally no.

First, whether there is any direct connection between the transmitter
case
(i.e., the outer shield of the coax connecting the transmitter to the
ATU)
and the ground terminal at the output of the ATU is entirely
coincidental.
Well, not really coincidental. It would be better to say that such a
direct
connection is not required. A good many ATU designs utilize inductive
coupling to the transmitter, or to the antenna, and a direct connection
in
those cases is purely optional.

The common marine ATUs, however, rely on a form of L-matching circuit in
which there IS a direct connection between input and output "grounds".
And
so the transmitter case winds up being connected directly to the ATU
ground
terminal and, therefore, to the vessel's RF ground system, whatever that
might be.

We need to keep in mind that the proper functioning of an antenna,
tuner,
transmission line, and transmitter, whether on a boat or off, does not
require as a matter of theory that the transmitter case be connected to
RF
ground.

As a practical matter though, the transmitter and the transmission line
to
the tuner are both in the very near field of the antenna. This is
especially
true on a boat. RF from the antenna can travel along the outer shield of
the
coax, along microphone, speaker, and power cables and get back inside
the
transmitter with difficult-to-predict consequences!

Getting to the real point, now. So sometimes, we need to do things like
run
a copper foil (low impedance) RF ground connection from the transmitter
case
to the boat's RF ground system. Sometimes it will help, sometimes it can
make matters worse. Sorry. Also, the system is likely to behave
differently
at different frequencies. There are ways to test for these currents and
often ferrites can be used in the lines to choke problem currents.

Finally, caution should be exercised in relying on copper foil to
provide
lightning protection. It would vaporize like an old-fashioned fuse with
any
significant current flow. It would be fine, however, for draining off
charge
accumulations from masts and wire rigging.

Hope this helps.


Chuck

SSB Antenna connection
 

In article ,
"Dave Morschhauser" wrote:

All --

Please comment on the following:

What about using copper tubing as an RF ground connection? Since the
current flows on the surface, a tube seems to be the most space efficient
way to get a large surface area. PI*R seems to say that a 1" copper tube
would be as effective as a 3" or so copper foil.

Any thoughts?

Thanks,
Dave.

"Bruce in Alaska" wrote in message
...
In article ulztc.40$Y21.34@lakeread02,
"Jack Painter" wrote:

"Bruce in Alaska" wrote in message
"Jack Painter" wrote:

Major snippage



I don't know who taught you your math but 1" cooper tubing doesn't even
come close to the surface area per length of 3" copper foil. It isn't
the DC amps that you need to worry about it is the Impedance of the
connection between the RF Ground System and the Ground stud on the
Antenna Tuner. Lower impedance better Rf Ground. It is the Ground
that makes the Antenna work.

Bruce in alaska
--
add a 2 before @

SSB Antenna connection
 

In article mYIuc.10643$ig5.6123@edtnps89,
"Gordon Wedman" wrote:

Well as I mentioned previously, Icom's printed literature on
antenna/transciever installation recommends grounding the transmitter to the
same ground ("boat ground") as the tuner using foil. Of course the Icom
tech that I contacted about this said not to ground the radio so everyone is
confused about this..................

The only people who seem to be confused are those folks who don't have
much experience in MF/HF Marine Radio Antenna System installation and
design. those of us who have been doing this work for more than 30
years have had this figured out for 28 of them. I know one of the Lead
Engineers @ Icom America in Seattle, and he is a great engineer, but has
very little Field Experience in Antenna System Design. When he used to
work for SEA, he was really good at the design of the CPU's that control
the radio's, but it was the SEA Chief Engineer that had 40 years in the
design of antennas for Maritime Radio uses. Marine Antenna design is
fast becoming a Lost Art.

Bruce in alaska
--
add a 2 before @

SSB Antenna connection
 

In article ,
"Meindert Sprang" wrote:

The best place for grounding is at the ATU. Grounding the TX is not
necessary then. If you only ground the TX, high RF currents will flow on the
outside of the coax from ATU to ground and as a result the coax will radiate
too.

Meindert
PE1GRV

One small caveat that I would make to the above is:

If the RF Ground should prove to be of maginally high in impedance at
the Tx Frequency, then the transmitter, if it is not connected to
that RF Ground by anything but the coax, the transmitter will then be
part of the antenna system, as it will tend to float above the RF Ground
by the impedance at the Antenna Tuners Ground Stud. This can cause the
radio to do very strange things, and on occasion can cause RF Burns
when the operator transmits with the ground connected mic hanger
disc in his palm. Alot more common in, the old days of, fixed tuned
channelized antenna tuners. Autotuners just aren't as efficent at tuning
the antennas as the fixed tuner cannelized tuners.

Bruce in alaska
--
add a 2 before @

SSB Antenna connection
 

"Bruce in Alaska" wrote in message
...
In article ,
"Dave Morschhauser" wrote:

All --

Please comment on the following:

What about using copper tubing as an RF ground connection? Since the
current flows on the surface, a tube seems to be the most space
efficient
way to get a large surface area. PI*R seems to say that a 1" copper
tube
would be as effective as a 3" or so copper foil.

Any thoughts?

Thanks,
Dave.

"Bruce in Alaska" wrote in message
...
In article ulztc.40$Y21.34@lakeread02,
"Jack Painter" wrote:

"Bruce in Alaska" wrote in message
"Jack Painter" wrote:

Major snippage



I don't know who taught you your math but 1" cooper tubing doesn't even
come close to the surface area per length of 3" copper foil. It isn't
the DC amps that you need to worry about it is the Impedance of the
connection between the RF Ground System and the Ground stud on the
Antenna Tuner. Lower impedance better Rf Ground. It is the Ground
that makes the Antenna work.

Pi*D is circumference, or Pi2R.

1" pipe exceeds the surface area of 3" strap. As totally impractical as
copper pipe would be as a bonding conductor in almost any application, it
would make an excellent RF ground connection on shore facilities where it
would offer several times the surface area of a solid ground rod half it's
diameter. Copper pipe is commonly filled with conductive salts which leech
through holes in the pipe to maintain high conductivity in ground rod
installations.

Best regards,

Jack Painter
Virginia Beach, Va

SSB Antenna connection
 

"Meindert Sprang" wrote in message
..
Much snippage...
..
Only if you feed the 1/2 in the low impedance point, which is halfway in
the
middel. Since this is impractical on a boat, feed it at the endpoint. But
at
the endpoint of a 1/2 wave, the impedance is very high so you need the
least
capacitance you can get at the antenna feedpoint. So GT15 is ok, but keep
it
1" away from any grounded or other conductive area (like strapping the
GTO15
to the uninsulated lower part of the backstay with tie-raps... BAD
PRACTICE).

Meindert
PE1GRV

Is the 1" just a rule of thumb or is there some engineering calculations to
support this distance? I see many sailboats with 1" varnished wooden dowels
or even plastic hair curlers with cable ties used to keep the GTO15 off the
uninsulated backstay wire. I have a feeling wider spacing would be even
better.Comments please.
Doug K7ABX

SSB Antenna connection
 

"Doug" wrote in message
link.net...

"Meindert Sprang" wrote in message
..
So GT15 is ok, but keep it 1" away from any grounded or other conductive
area (like strapping the
GTO15 to the uninsulated lower part of the backstay with tie-raps... BAD
PRACTICE).

Meindert
PE1GRV

Is the 1" just a rule of thumb or is there some engineering calculations
to
support this distance?

It is more a rule of thumb. At 1" the extra capacity caused by the wire
close to the backstay is low enough not to have any bad influence on the
high impedant line.

Here's some math: two wires, 1 mm in diameter, 25.4mm (1") spaced apart, 1
meter long form a capacitor of 0.35pF, which is hardly noticable at HF
frequencies (15kOhm at 30MHz).
The same wires, 1mm apart, form a capacitor of 9pF. With solid insulation
between them, the capacity goes up by a factor of 2 to 10, depending on the
type of insulation used. Coax, for instance, has a typical capacitance of
100pF/meter.

So 1" is a rule of thumb. For SI minded people, 1cm would probably do fine
too.

Meindert

SSB Antenna connection
 

In article .net,
"Doug" wrote:

"Meindert Sprang" wrote in message
..
Much snippage...
.
Only if you feed the 1/2 in the low impedance point, which is halfway in
the
middel. Since this is impractical on a boat, feed it at the endpoint. But
at
the endpoint of a 1/2 wave, the impedance is very high so you need the
least
capacitance you can get at the antenna feedpoint. So GT15 is ok, but keep
it
1" away from any grounded or other conductive area (like strapping the
GTO15
to the uninsulated lower part of the backstay with tie-raps... BAD
PRACTICE).

Meindert
PE1GRV

Is the 1" just a rule of thumb or is there some engineering calculations to
support this distance? I see many sailboats with 1" varnished wooden dowels
or even plastic hair curlers with cable ties used to keep the GTO15 off the
uninsulated backstay wire. I have a feeling wider spacing would be even
better.Comments please.
Doug K7ABX



The 1" is a "Rule Of Dumb", that does allow for some decoupling, but
doesn't really decouple the antenna for the parallel Grounded backstay.
One can calculate the capacative interaction between the two, or one
can just use the "Rule of Dumb" and let the antenna tuner correct for
the extra capacitance. Just understand that most autotuners will not
like the extra capacitance on the output, and this will tend to widen
out the 1/2 wavelength tuning problems that all endfeed autotuners have.

Bruce in alaska
--
add a 2 before @

SSB Antenna connection
 

In article RI1vc.2576$Y21.814@lakeread02,
"Jack Painter" wrote:

Pi*D is circumference, or Pi2R.

1" pipe exceeds the surface area of 3" strap. As totally impractical as
copper pipe would be as a bonding conductor in almost any application, it
would make an excellent RF ground connection on shore facilities where it
would offer several times the surface area of a solid ground rod half it's
diameter. Copper pipe is commonly filled with conductive salts which leech
through holes in the pipe to maintain high conductivity in ground rod
installations.

Best regards,

Jack Painter
Virginia Beach, Va

Jack my boy you need to go back to school and refresh your geometry.

Pi*D is circumfrence This is true. Now what is the outside surface
area for one inch of length of 1" dia copper pipe?
Lets see 3.1416*1"=3.1416 3.1416*1" length = 3.1416 Square Inches.


Now lets look at 3" copper foil.....ok for Inch of length
we have 3.0 inches square inches of surface area on the front
side and 3.0 square inches of surface area on the back side.
That makes a total of 6 Square Inches of surface area per 1"
of length. We will ignore the thickness of the foil, just because
it isn't significant for the terms we are discussion here.

Now which has more surface area per linear inch?

3.1416 Square Inches for the copper tubing........

or

6 square Inches for the 3" foil........

Hmmmmmmm, wonder what could be the answer.........

If you like, you could think of the copper tubing as being flattened
into a bar and measure it again and it still wouldn't approch a 3" foil
for surface area.

You don't get to include the inside surface area of the tubing, because
RF flows on the outside surface only, but even if you did, you would
still come up a bit short on surface area when compared to 3" copper
foil.

We aren't talking about Shoreside systems on this thread as the original
poster specificly asked about shipboard installations. You observations
about copper pipes being used for Grounding Rods in MF/HF systems
instead of solid copper has some merit, but most RF Grounded Antenna
Systems in the Maritime Mobile Radio Service use a 1/4 Lambda Radial
Grounding System designed for the lowest Frequency that the antenna will
be used on, with interspeced radials cut for 1/4 Lambda at the other
major operating bands. These type antennas really fell out of favor
in the 30's and 40's for Non RF Grounded Antennas like the Rhombics
that Pt. Reyes, CA (KMI) used. They had a set of Phased Rhombics that
could be steered to any point from due South to due North, on 4, 6, 8,
12,16, and 22 Mhz. No Grounding required, and a Frontend smoking signal
everywhere in the Pacific.



Bruce in alaska
--
add a 2 before @

SSB Antenna connection
 

"Bruce in Alaska" wrote
"Jack Painter" wrote:

Pi*D is circumference, or Pi2R.

1" pipe exceeds the surface area of 3" strap. As totally impractical as
copper pipe would be as a bonding conductor in almost any application,
it
would make an excellent RF ground connection on shore facilities where
it
would offer several times the surface area of a solid ground rod half
it's
diameter. Copper pipe is commonly filled with conductive salts which
leech
through holes in the pipe to maintain high conductivity in ground rod
installations.

Jack my boy you need to go back to school and refresh your geometry.

Pi*D is circumfrence This is true. Now what is the outside surface
area for one inch of length of 1" dia copper pipe?
Lets see 3.1416*1"=3.1416 3.1416*1" length = 3.1416 Square Inches.


Now lets look at 3" copper foil.....ok for Inch of length
we have 3.0 inches square inches of surface area on the front
side and 3.0 square inches of surface area on the back side.
That makes a total of 6 Square Inches of surface area per 1"
of length. We will ignore the thickness of the foil, just because
it isn't significant for the terms we are discussion here.

Now which has more surface area per linear inch?

3.1416 Square Inches for the copper tubing........

or

6 square Inches for the 3" foil........

Hmmmmmmm, wonder what could be the answer.........

If you like, you could think of the copper tubing as being flattened
into a bar and measure it again and it still wouldn't approch a 3" foil
for surface area.

You don't get to include the inside surface area of the tubing, because
RF flows on the outside surface only, but even if you did, you would
still come up a bit short on surface area when compared to 3" copper
foil.

C'mon ol' salt, you should know the inside of copper pipe is electrically
identical to both sides of copper strap when a bonding connection is made to
either. Skin effect of electrical current is felt equally on both in _that_
condition. Electromagnetic induction on a material from one outside
direction sees skin effect on the outside surface only of a closed
structure, cabinet, pipe, etc. But we are not talking about EMF's. We are
talking about a bonded connection that has RF voltages, and during tuning
applications, RF current applied directly to the conductor. Respectfully, my
geometry and description of the conductor skin-effect condition are both
correct, and 1" pipe exceeds the surface area of 3" strap.

Best regards,

Jack Painter
Virginia Beach, Va

SSB Antenna connection
 

"Jack Painter" wrote in message
news:p3lvc.5786$Y21.4832@lakeread02...
C'mon ol' salt, you should know the inside of copper pipe is electrically
identical to both sides of copper strap when a bonding connection is made
to
either. Skin effect of electrical current is felt equally on both in
_that_
condition.

No it isn't. Consider a massive rod of 1". RF flows at the outside due to
skin effect. No remove the innards of the rod, leaving, say 1/16" of wall.
Why would current suddenly flow at the inner surface? It isn't, for the same
reason it was on the outside when the rod was massive.

Besides, heavy coils in radio stations are all tubes and cooled by running
water through them. Due to the skinn effect, the water is not 'touched' by
the RF.

Electromagnetic induction on a material from one outside
direction sees skin effect on the outside surface only of a closed
structure, cabinet, pipe, etc. But we are not talking about EMF's.

Yes we are. And EMF is exactly the reason why the electrons start to repell
eachother. And the only place where they are as far apart as possible is on
the outside of the tube.

Meindert