In article ,
says...
I have a coax lead coming from the top of an ICOM ATU. This has a core
and a screen. It comes up through the deck to an insulated backstay.
Question : should I ignore the screen, and simply cut it back? Or
should I connect the screen at the ATU end to the ship's earth?

thanks


There have been a number of threads about your question. Try searching
google/groups.

BTW, in the following, "ground" = "earth".

The short and over simplified answer is to connect the shield braid
(screen) to the antenna tuner ground. At the antenna end, if feasable,
the shield could/should be connected to the stay on the other side of
the lower insulator.
But... The coax is likely to become part of the radiator and the
tuner/antenna will likely perform less well than with a more "ideal"
configuration.

Idealy the tuner should connect to the backstay with unshielded high
voltage wire (like spark ignition wire - I forget the exact
designation). This *will* be part of the radiating antenna and should
be kept clear of people, other wiring/electronics, and metal. This means
mounting the tuner near the antenna feed - and very near a good ground.
The ground from the tuner should be as straight and short as possible to
ship's ground and water ground.

Ferrite sleeves can be placed over the coax feeding the tuner (at the
tuner) to help minimize stray radiation from the line between the radio
and tuner.

Woody

In article et,
Woody wrote:

In article ,
says...
I have a coax lead coming from the top of an ICOM ATU. This has a core
and a screen. It comes up through the deck to an insulated backstay.
Question : should I ignore the screen, and simply cut it back? Or
should I connect the screen at the ATU end to the ship's earth?

thanks


There have been a number of threads about your question. Try searching
google/groups.

BTW, in the following, "ground" = "earth".

The short and over simplified answer is to connect the shield braid
(screen) to the antenna tuner ground. At the antenna end, if feasable,
the shield could/should be connected to the stay on the other side of
the lower insulator.
But... The coax is likely to become part of the radiator and the
tuner/antenna will likely perform less well than with a more "ideal"
configuration.

Idealy the tuner should connect to the backstay with unshielded high
voltage wire (like spark ignition wire - I forget the exact
designation). This *will* be part of the radiating antenna and should
be kept clear of people, other wiring/electronics, and metal. This means
mounting the tuner near the antenna feed - and very near a good ground.
The ground from the tuner should be as straight and short as possible to
ship's ground and water ground.

Ferrite sleeves can be placed over the coax feeding the tuner (at the
tuner) to help minimize stray radiation from the line between the radio
and tuner.

Woody

I would try and correct the above, but it is Sunday, and I don't work on
Sundays, and correcting the above would be an an hours of work........


Me advice is only as good as what you paid for it............

Followup to msg on Sun, 17 Oct 2004 11:20:20 GMT, Woody
:
(Original msg on bottom)

The name is GTO15, you can find it also on the WestMarine online
sales.

Therefo no shield but 15000 V insulated cable.

In case the non insulated part of the backstay is connected to ground,
better is to put some spaced insulated sticks to held the GTO15 about
7 cm far away from the backstay (hope you can understand my bad
english), where the cable goes down to the deck.

Ciao Manlio

dealy the tuner should connect to the backstay with unshielded high
voltage wire (like spark ignition wire - I forget the exact
designation)

Manlio Laschena
s/y Amarose
http://Delphi-Jedi.org

thanks everybody for your help. Much appreciated