Posted by
Don Wilhelm-3 on
Nov 02, 2005; 6:27pm
URL: http://elecraft.85.s1.nabble.com/Counterpoises-for-KAT100-tp383349p383350.html
Gil,
For effective counterpoise operation, you should tune them to the proper
length. If you tune them in place, you will not have to worry about ground
effects and proximity to other objects detuning them. Cut them longer than
you think you will need. Yes, you can connect them to your single 6 ft.
wire as long as you include that wire in the tuning process.
If you have an antenna analyzer, or better yet, an old fashioned grid dip
meter, put the wires in place (disconnected from the KAT100) and find the
resonant frequency of the counterpoise wire (hint, it will be a half wave
'dipole' at double the operating frequency and should show resonance by a
dip or zero impedance - how to couple the meter into the wire is the main
problem to be solved here). Once you get them tuned, they should be
effective in providing a good RF Ground at the KAT100 ground connection
(where it should be).
Yes, the wires should be at least 6 to 8 feet high - in other words, keep
them out of reach for humans and pets - they will carry RF Current and have
high RF Voltage at the far end, so plan on using adequate insulators.
73,
Don W3FPR
> -----Original Message-----
> From:
[hidden email]
> [mailto:
[hidden email]]On Behalf Of Gil Stacy
> Sent: Wednesday, November 02, 2005 11:57 AM
> To:
[hidden email]
> Subject: [Elecraft] Counterpoises for KAT100
>
>
> Id like to pigtail counterpoises for 10, 30, 80 and 160 meters for my
> 200+/- wire which is configured as an endfed inverted U up about 65-70.
> The horizontal run is about 90; the down-turned end is about 50
> long, and
> stops about 15 from earth. The horizontal run is across a
> steel-shingled
> roof with a ridgeline up about 26 from earth. (If the 50' downturn is
> counterproductive, I could eliminate it, but the antenna doubles on my dx
> xtal radio set and seems to work better with this ant.)
>
> For the ¼ wave counterpoises, Id like to feed them to my KAT100 with a
> single wire 6 long. I would prefer to join the longer c.p.s to this
> single wire outside the window. Is this practical? I assume I would
> subtract the 6 from the calculated ¼ wavelength of each band and attach
> wires of respective lengths to the 6 wire. Ill probably pigtail the 10
> meter c.p. closer to the KAT100 inside the shack and keep it along the
> floorboard.
>
> C.P. height: Resources indicate a preferred height of 6-8 above
> ground.
> Is this a minimum or could I lay the 80 and 160 meter c.p.s on top of my
> roof? I will not be able to lay out the 160 meter c.p. in a
> straight line
> in any event.
>
> Tnx es 73, Gil NN4CW
>
>
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