Very occasionally the K3 ATU will not find a good match and you may be
able to do better by setting the tuning elements yourself. That is the
case for my 70' endfed wire on 160m. The ATU will match it on all other
bands though.
To tune the elements manually select "LC Set" in the Config:KAT3 menu.
73,
Drew
AF2Z
On 12/12/20 12:55, Walter Underwood wrote:
A random-length wire is usually chosen to avoid a half-wavelength on the
frequencies you’ll be using. A more accurate term is non-resonant end-fed
antenna.
Avoiding half-wavelengths means the impedance will not be 5000 Ω or greater,
but it will be pretty high. Or low. The SWR on the feed line will be large and
a high impedance feed point is pretty sensitive to surrounding objects
(capacitance).
So:
1. Keep the coax short and low loss.
2. At the antenna, connect some sort of counterpoise or RF ground to the shield
of the coax. This can be a ground rod, a radial system, or a wire laying on the
ground. If you don’t do that, the RF ground will be the coax and everything
connected to it, including your K3.
3. After that, tell the ATU to tune it and wait for it to find a solution.
4. If it won’t match, change something. Maybe the length of the wire, maybe the
position, maybe the counterpoise.
If this is a long-term setup, a common mode choke near the rig is a good idea.
Even with a counterpoise, some of that RF energy is going to be on the shield.
For field deployments with the KX3, I run with no feed line at all. The antenna
wire and counterpoise wire are connected directly to the KX3 with a double
binding post adapter.
wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)
On Dec 12, 2020, at 9:41 AM, Mister Mike <[email protected]> wrote:
What is the best way to do this? I am not familiar with automatic tuners.
TIA,
Michael, W1RC
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