2 Coil beam Setup on a chevy G20 van

[Hitman 043]

I have been running a 2 antenna beam setup with the front hot and rear grounded or capped for years with very low reflect. I've always run into problems with reflect and blowing boxes when I run 2 coil antennas (davemade&pony) coils between 6-7 ft. apart. I do fine when I keep the volts down, But when I volt anywhere between 15-21 volts I usually blow within minutes to a hour. I can have less than 1% reflect on the coils and still have this problem. Does anyone know how I can beat this? I forgot to mention that when I run the two 1/4 wave war stick beam setup (front hot) everything works fine and I can run up to 21.5 volts on my davemade driver and main box. I hope that someone can help me because it is getting to cold for me to keep climbing my old self on top of my van when I want to drop down the worldwide Maul. I would rather leave my ride around coils on.

Thanks in advance,
Hitman 043

 

[freecell]

how long are the shafts on the antennas?

 

[Hitman 043]

2 antenna beam setup with coils

The Shafts on both antennas are about 17 inches below the coil. I have tried shorter shafts but they really didn't work.
Hitman 043

 

[freecell]

the shafts need to be longer.

 

[Master Chief]

the shafts need to be longer.

Why? I know very little about dual antenna competition set-ups. So I'm watching intently. Please get into the advantages of grounding the rear as well as making it hot.

Also, the longer directors added to the front of the vehicle just doesn't seem to jive with a loaded 1/4 wave driven element and the horizontal ground plane (vehicle roof). How does that all work?

This should make a very interesting thread!

bob85, maybe you can post one of your famous drawings showing how it all works......that is if you understand it as well.

 

[excavator701]

antenna

im watching intently also i hope someone with a lot of knowledge answers to this thread because i also want to learn how to do the 2 antennas hot with low reflect!!!!!!!! i have tried before but failes never could get anything to work

 

[W5LZ]

How do you make it work? Simple, match impedances and use the correct 'phasing'/spacing/element lengths for a directional radiation pattern. How you go about doing that isn't exactly the simplest thing in the world, but certainly not all that difficult or mysterious.
Forget about using coax as the impedance matching 'devices' at the power levels you're talking about. Just isn't possible because ~no~ coax cable's electrical characteristics will handle it. Coax length for phasing? Sure, but you'd better match impedances before you start the phasing.
Doesn't much matter what 'kind' of element you use for the elements in the directional antenna, there are a couple of things that are always going to hold true. Such as the 'director' element needs to be shorter than the driven element, and the reflector element needs to be longer than the driven element, if only one element is driven. (Grounding the reflector element through a capacitor has the effect of shortening the element. Anybody ever thing about that?)
Something else to think about is that coils are 'lossy' when used in a radiating element. If the shortening affect of a coil is what you're after then that loss is acceptible, I guess. If that shortening isn't the whole idea, why use the coil, they certainly don't improve the radiation characteristics of an antenna. How much loss? Not a hell of a lot, but there is some there that does not get radiated as signal, which seems like the whole purpose in a 'shouting' contest. Ain't it?
The 'simplest' option is to throw lots of money at the problem. If you don't mind waiting till all of the ice dissapears, bring it on down here and I'll fix it. Don't forget that 'lots of money' thingy! I'm very receptive to lots of money...
- 'Doc