SHould this be grounded or not?
 

Should a dual band open stub j pole like the one arrow makes be
grounded or not? Seems like someone told me no j polls should be
grounded according to their nec program. The website says it can be
grounded or not.
If it should not, then how do you protect from lightening?

Should a dual band open stub j pole like the one arrow makes be
grounded or not? Seems like someone told me no j polls should be
grounded according to their nec program. The website says it can be
grounded or not.
If it should not, then how do you protect from lightening?
=================================================
Earthing any antenna does not protect against a lightning strike.
The best way to protect equipment attached to any antenna is to disconnect
the feeder near the radio equipment , keeping the feeder metal connections
away from any other metal.

When I go away from home expecting 'static' activity and lightning ,I always
disconnect the antenna feeders and 'park' the connectors inside a plastic
box

However ,earthing an antenna does help preventing static charge build-up .
Hence following a feeder disconnect ,before reconnecting it to radio
equipment , I briefly 'touch' the feeder connection(s) to earth.
My double ZEPP or Doublet wire dipole with balanced ribbon feeder has 2 ea
composite 47 kOhms resistor at the matching unit (tuner if you wish)
connected to chassis/earth.

Frank GM0CSZ / KN6WH

But what if something happens and your away from home, like a freak
thunderstorm?

Should a j pole like this be grounded or not?

On 25 Jan 2005 14:11:30 -0800, wrote:

But what if something happens and your away from home, like a freak
thunderstorm?

Should a j pole like this be grounded or not?

It should be grounded for lightening (for RF there is no need). Also
A spark gap or similar device should be on the coax as the fed element
is not grounded (all the arrow OSJs). It is sufficient to bond its
mounting to the metal mast (or tower) and the mast to the earth
ground.

Allison

On Tue, 25 Jan 2005 21:34:44 GMT, "Highland Ham"
wrote:

Should a dual band open stub j pole like the one arrow makes be
grounded or not? Seems like someone told me no j polls should be
grounded according to their nec program. The website says it can be
grounded or not.
If it should not, then how do you protect from lightening?
=============================================== ==
Earthing any antenna does not protect against a lightning strike.
The best way to protect equipment attached to any antenna is to disconnect
the feeder near the radio equipment , keeping the feeder metal connections
away from any other metal.

When I go away from home expecting 'static' activity and lightning ,I always
disconnect the antenna feeders and 'park' the connectors inside a plastic
box

However ,earthing an antenna does help preventing static charge build-up .
Hence following a feeder disconnect ,before reconnecting it to radio
equipment , I briefly 'touch' the feeder connection(s) to earth.
My double ZEPP or Doublet wire dipole with balanced ribbon feeder has 2 ea
composite 47 kOhms resistor at the matching unit (tuner if you wish)
connected to chassis/earth.

Frank GM0CSZ / KN6WH



You don't put the end of the cable in a pickle jar filled with water?

73
Gary K4FMX

Gary Schafer wrote:

You don't put the end of the cable in a pickle jar filled with water?

Totally ineffective. The proper way earth your cable is into the nearest
available plant-pot.

People did this in the days of Mr Marconi and aspidistra plants, so it
must be all right... maybe you'd better talk to the plant first, to make
sure the pot is filled with genuine earth.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian White, G3SEK wrote:
Gary Schafer wrote:


You don't put the end of the cable in a pickle jar filled with water?

Totally ineffective. The proper way earth your cable is into the nearest
available plant-pot.

People did this in the days of Mr Marconi and aspidistra plants, so it
must be all right... maybe you'd better talk to the plant first, to make
sure the pot is filled with genuine earth.

I've heard of using an "artificial ground". Is this where you fill the
pot with vermiculite or styrofoam?

Roy Lewallen, W7EL

Roy Lewallen wrote:
Ian White, G3SEK wrote:
Gary Schafer wrote:


You don't put the end of the cable in a pickle jar filled with water?

Totally ineffective. The proper way earth your cable is into the
nearest available plant-pot.
People did this in the days of Mr Marconi and aspidistra plants, so
it must be all right... maybe you'd better talk to the plant first, to
make sure the pot is filled with genuine earth.

I've heard of using an "artificial ground". Is this where you fill the
pot with vermiculite or styrofoam?

Exactly. You're really getting the hang of it now.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

I think I just had an ephihony,

A regular j pole uses a shorted stub, so, If the regular j pole was
grounded, no need to cround the coax?

On 26 Jan 2005 05:45:12 -0800, wrote:

I think I just had an ephihony,

A regular j pole uses a shorted stub, so, If the regular j pole was
grounded, no need to cround the coax?

Ah not quite. The coax shold be grounded also. See the PolyPhaser
site about lightining protection. It makes little difference as to
the type of antenna from a practical standpoint of lightining
protection.

The key issue around lightining is what are best described as sneak
paths. Due to the imense current (in excess of 10,000 Amps) even a
fraction of an ohm resistance difference between the strike point and
ground allows a significant voltage to develope (10,000A*
0.1ohm=1000V). I might add that in that example a resistance of 0.1
ohm is likely an unrealisticly low number. Also since it's a pulse
of energy it induces currents just like the magnetic field in a
transformer or generator so even nearby conductive objects can have
currents and voltages induced on them. This gives rise to those sneak
paths. So this means if you want tp prevent a lightining hit (or
near miss!) from finding its way into the shack you will have to pay
attention to details. This includes phone and power lines. I've
not gone into a lot of explanation here and I've glossed over much
as well so please research it deeper.

As side note: I've been hear missed three times and all three times
the greatest destruction came via the phone lines! I've lost phones,
computers because the spike was propagated from the phone to the
computer that was connected to it via an external modem. This can
give an idea of sneak paths. To truly effect a Lightining protection
plan you have to address the antenna system (antenna, tower,
feedlines), the power system (what the radio runs off of) and the
phone system (you may have a computer with DSL, cable modem
or Phone modem connected to the radio). It's not difficult but,
attention to small details and following known guidelines is
important. Oh and don't scrimp, a good system is cheap compared
to damaged electronis or a house fire.

Allison
KB1GMX