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Author Topic: cha emcomm ii counterpoise  (Read 396 times)

K5BOU

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cha emcomm ii counterpoise
« on: March 18, 2021, 08:21:46 PM »

I/m about to install my Chameleon emcomm II. Hight end will be around 18 ft.
1) how low from the ground need to be the match box
2) does is better to have multiples counterpoise and if yes how long or only one
3) I will use 100 ft coaxial.
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WB6BYU

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Re: cha emcomm ii counterpoise
« Reply #1 on: March 19, 2021, 10:13:35 AM »

Quote from: K5BOU

I/m about to install my Chameleon emcomm II. Hight end will be around 18 ft.
1) how low from the ground need to be the match box



As high as possible will probably give best results.

Obviously, if it is more than 18 feet than it is no longer the low end
of the antenna.

Ground losses increase as you lower the feedpoint.  You have to
weigh that against installation convenience.  That's a personal
decision.


Quote

2) does is better to have multiples counterpoise and if yes how long or only one



The best counterpoise is probably a wire the same length as the
radiator running in the opposite direction and elevated at about
the same height.  Basically a dipole. 

Or one such counterpose / radial cut to 1/4 wavelength for each
band you want to use and elevated in the same manner.  They
don't have to run straight off the back, but can angle as needed
to tie to available supports.

That assumes that a primary objective is radiated signal strength.
Other operators may have different priorities.



Quote

3) I will use 100 ft coaxial.



That should, at least, reduce the stress on your tuner by lowering
the SWR it sees (due to losses in the feedline).


A couple of the local ARES operators use that antenna, and they
seem to really like it.  On one recent operation, however, they
complained that band conditions were so bad that the net control
couldn't hear them.  Those using portable dipoles didn't have that
problem, however...

One of them did observe that, when he mounted the antenna as
a dipole at 20 feet, it worked a whole lot better!

KH6AQ

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Re: cha emcomm ii counterpoise
« Reply #2 on: April 02, 2021, 12:31:21 PM »

What is your CHA EmcommII mounted on? A conductive mast, a non-conductive mast, a building?



Manual  https://static.dxengineering.com/global/images/instructions/cha-emcomm-ii.pdf

Documentation   https://www.dxengineering.com/parts/cha-emcomm-ii/documentation

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KN6SU

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Re: cha emcomm ii counterpoise
« Reply #3 on: May 09, 2021, 09:26:43 AM »

Quote from: K5BOU









Quote

3) I will use 100 ft coaxial.


That should, at least, reduce the stress on your tuner by lowering
the SWR it sees (due to losses in the feedline).


I think the OP mentioned the 100'  coax feedline because he was thinking that the braid could function as a counterpoise (as it can) and may have been wondering what might be an optimal coax length for that purpose. Of course I could be wrong about the OP's reason for mentioning it.
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