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isolation confusion

S

stingray

Member
Dec 12, 2008
85
1
18
if i isolate the antenna from the mast where do i connect a ground wire to,
the antenna bracket itself or to the mast which is separate from the antenna?
i dont get it.
 

Check this out from the earlier thread on this issue. Sorry for the type-O in my original post below, if the word insulate used there confused anyone.

Marconi said:
If you do that Splash, you just be defeating the purpose. To isolate and then bypass the isolation makes no sense if the modification works.

Maybe you are trying to help prevent damages due to lightning. It is a problem to consider, but you are just defeating the purpose of the modification. Either way the coax is still vulnerable to lightning and you cannot get around that. Running the coax under-ground and making a coil at some point underground will help some maybe. There are other methods to consider also.

In this three prong antenna idea you're talking about, isolating is only a part of the solution you seek. The balun you are getting is another part, as is adding the GPK. Will just one idea work, will two work or does it take all three. Some have noticed gains just by isolating the GPK from the Earth.

I believe adding the balun with the other two mods makes the best sense, because of the way currents act in this case.

Good luck
Click to expand...
 
stingray said:
if i isolate the antenna from the mast where do i connect a ground wire to,
the antenna bracket itself or to the mast which is separate from the antenna?
i dont get it.
Click to expand...

ok, i'll play..... is it a hertz or a marconi type antenna? :p
 
stingray said:
if i isolate the antenna from the mast where do i connect a ground wire to,
the antenna bracket itself or to the mast which is separate from the antenna?
i dont get it.
Click to expand...
The ground wire is already there in the form of the shielding of the coax connected to the radio, that is your rf ground and a dc ground is only for safety such as to discharge lightning strikes which are very uncommon.

The best thing you could do even with a proper dc ground connection from the antenna would be to toss your coax out the window everytime a thunderstorm appoached for the ultimate safety factor.

But if you chose to isolate the antenna from the mast you're gonna want to add a choke in the feedline at the point of isolation to reduce cmc's from traveling down the coax and on top of that you're sure to need some type of ground plane radial system at the feed point of the antenna.
 
what i still am not getting is this- if i isolate the antenna from the mast,
where do i hook up a ground wire (if at all) because if the antenna is supposed to be isolated from the mast to keep the mast from being part of the antenna, what is the point of adding a ground wire that will be part of the antenna??? DO I ADD A GROUND WIRE TO AN ISOLATED ANTENNA IS WHAT I AM TRYING TO FIND OUT. does the earth ground help with noise or is the coax ground good enough?
 
half wave aluminum ground plane with radials. (antenna specialists mighty magnum 3). what will be the best way to install this thing. (i want to do it right ONCE)
 
mackmobile43 said:
The ground wire is already there in the form of the shielding of the coax connected to the radio, that is your rf ground and a dc ground is only for safety such as to discharge lightning strikes which are very uncommon.

The best thing you could do even with a proper dc ground connection from the antenna would be to toss your coax out the window every time a thunderstorm approached for the ultimate safety factor.

But if you chose to isolate the antenna from the mast you're gonna want to add a choke in the feedline at the point of isolation to reduce cmc's from traveling down the coax and on top of that you're sure to need some type of ground plane radial system at the feed point of the antenna.
Click to expand...

Whilst tossing the coax out of the window sounds like a good idea, one thing you have to watch out for is static electricity build up in the coax, one you could get a very high voltage jolt when yo pick the plug up, or even worse you could discharge the charge when you plug it back into the radio taking out the front end fets or transistors!

Better to ensure that the plug is grounded so any charge can drain away into the ground, or failing that touch the centre of the coax onto your earth rod. I have seen large sparks jumping out of a PL Plug to a cold water tap over 6 inches away! mind you that was during the storm itself.
Either way try not to get bitten it hurts!

:D
 
Some days things just don't come together to well with group discussions.

and this is one of those days!
 
"I have seen large sparks jumping out of a PL Plug to a cold water tap over 6 inches away! mind you that was during the storm itself."

in case no one ever told you playing benjamin franklin in a storm isnt very healthy .
but if you insist ......... have someone video it for youtube next time . :)
 
DX-DIGGER said:
Whilst tossing the coax out of the window sounds like a good idea, one thing you have to watch out for is static electricity build up in the coax, one you could get a very high voltage jolt when yo pick the plug up, or even worse you could discharge the charge when you plug it back into the radio taking out the front end fets or transistors!

Better to ensure that the plug is grounded so any charge can drain away into the ground, or failing that touch the centre of the coax onto your earth rod. I have seen large sparks jumping out of a PL Plug to a cold water tap over 6 inches away! mind you that was during the storm itself.
Either way try not to get bitten it hurts!

:D
Click to expand...
I look at it this way, "the lord giveth and the lord taketh away":D simple fact is I don't use an antenna that does not have a direct dc path to earth regardless of it's mechanical design and that's why I posted in another thread that when isolating the antenna from dc you could use a choke inline and simply dc ground the coax shield.
 

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