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

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

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.

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.

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.

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

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 @

"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

"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

"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