are gamma matches excellent lightning protectors ?

[BOOTY MONSTER]

i was re-reading a article about dc grounded antennas over at Industrial Communication Engineers, LTD. and i guess i never paid attention to the last paragraph ...

Special Publications | Technical Publication #80

"If your in the market for an antenna and wish to enjoy a bit of protection select the ones offered that use capacitor or link feed systems. Capacitor feed systems such as gamma matches are excellent feed systems and lightning protectors as well. They isolate the center conductor and force lightning into the shield."

is this true ?

 

[Se7en]

i was re-reading a article about dc grounded antennas over at Industrial Communication Engineers, LTD. and i guess i never paid attention to the last paragraph ...

Special Publications | Technical Publication #80

"If your in the market for an antenna and wish to enjoy a bit of protection select the ones offered that use capacitor or link feed systems. Capacitor feed systems such as gamma matches are excellent feed systems and lightning protectors as well. They isolate the center conductor and force lightning into the shield."

is this true ?

sounds right to me. someone else elaborate, please?

 

[Robb]

Dunno Booty. I do know when a strike occurs it will get most everything around it too. If a bolt occurs from the base of a cloud and travels 1/2 mile or more to get to a car; there isn't much that is going to stop it. Least of all any insulation on coax or an antenna. If there is a metal sign on the side of the road - or even a small tree or bush - when a vehicle gets struck it often catches some of that discharge too. Lightning is some serious business, and I don't take chances with it at any time.

 

[Captain Kilowatt]

I think there is actually a misuse of terms in that article. A yagi antenna fed with a gamma match is still a DC ground antenna because all the elements are connected to ground in the middle as opposed to a series fed antenna where nothing is grounded like a simple 1/4 wave vertical. The gamma match itself simply presents a series capacitor that is in series with the feedline and offers nothing in the way of protection in the event of lightning strikes.Think about it, if a couple kilowatts is enough to blow a gamma match what is a few million watts from a lightning strike going to do? A mere 1/16 of an inch of nylon or polyethylene tubing is no match for a strike.

 

[mackmobile43]

I think BM has a fresh prescription filled.

 

[Captain Kilowatt]

I think BM has a fresh prescription filled.

Actually I was beginning to think he had one that needed to filled.:laugh:

 

[RatsoW8]

"Capacitor feed systems such as gamma matches are excellent feed systems and lightning protectors as well. They isolate the center conductor and force lightning into the shield."

Is this guy stoned, drunk or both?

 

[BOOTY MONSTER]

going to get my prescription filled when my pharmacist gets home from work later

hey CK , would it make more sense if the author said open circuit antenna rather than dc grounded antenna ?
the thin insulator gamma insulator (like you mentioned) is why i asked .

 

[Captain Kilowatt]

going to get my prescription filled when my pharmacist gets home from work later

hey CK , would it make more sense if the author said open circuit antenna rather than dc grounded antenna ?
the thin insulator gamma insulator (like you mentioned) is why i asked .

I guess it's all just a matter of what you really want to call it. Open circuit feed sounds like it has a problem while perhaps calling it "DC blocked feed" would more properly define what it really is. In any event what it really is is a small piece of plastic tubing that the author claims is capable of fending off the effects of a lightning strike.

 

[mackmobile43]

I guess it's all just a matter of what you really want to call it. Open circuit feed sounds like it has a problem while perhaps calling it "DC blocked feed" would more properly define what it really is. In event what it really is is a small piece of plastic tubing that the author claims is capable of fending off the effects of a lightning strike.

But doesn't a gamma match act as a capacitor that isn't charged until rf is placed into it?

And when overloaded by an electrical charge has to be discharged into a ground source at the opposite end of the coax?

 

[Captain Kilowatt]

But doesn't a gamma match act as a capacitor that isn't charged until rf is placed into it?

It doesn't take much to charge up a few tens of picofarads with 27 MHz.

And when overloaded by an electrical charge has to be discharged into a ground source at the opposite end of the coax?

That's usually the way it works. :laugh:

 

[mackmobile43]

and when that happens the static charge moving across the 2 parts of the gamma creates an arc and that has it's own frequency and that resulting drain of electrons creates a nasty noise in the receiver at the opposite end of the coax so I would say no BOOTY MONSTER a gamma match will not decrease any noise conditions.

 

[Captain Kilowatt]

Well Mack, that only happens the first time and then the radio is VERY quite so maybe it does work to reduce noise once it gets broken in.

 

[mackmobile43]

Well Mack, that only happens the first time and then the radio is VERY quite so maybe it does work to reduce noise once it gets broken in.

Agreed shall we call it the voice of GOD?

 

[Captain Kilowatt]

Voice of God. Hammer of Thor. Take your pick.