My Elecraft KX1 companion: an EFHW trapped

My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
My Elecraft KX1 companion: an EFHW trapped antenna for
40/30/20m
by Phil - lundi, janvier 18, 2016
http://f5iyj.com/2016/01/my-elecraft-kx1-companion-an-efhw-trapped-antenna-on-403020m/
I've got an old Elecraft KX1 I love. It is a perfect transceiver when you go hicking or travelling.
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My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
I am lucky to have the internal ATU so I could fire a wire in a tree and let's the ATU do its work. But
with a maximum of 3W, it is better sometimes to set up an antenna which can radiate the full power you
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My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
have, without dissipating power in the ATU.
Because I have the 30m option, I will need an antenna for the 40-30-20m.
I will build an End Fed Half Wave antenna for different reasons:
1. you don't need a long feeder (less weight when traveling)
2. you can use it as an inverted Vee or a slopper
3. you feed the antenna from its end (you can use it from your hotel window as a slopper)
4. you can use a light fishing pole (which doesn't have to resist to the coax weight)
5. As a half wave antenna, you don't need radials
So let's build a light EFHW.
I've read a post from the SOTA reflector about traps made from a SMT capacitor and coils. I did some
experiments but shortly identified the capacitor needs to be reinforced by soldering it on a PCB as it
cannot survive to the tension due to the coil or the antenna wire.
So I was working around a PCB drawing when I saw at SOTABeams what I was looking for. Using a
toroid for the coil is a nice idea so to not reinvent the wheel, I ordered one 'Pico trap' from SOTABeams:
So let's build a trap for
30m and another one for 20m.
I have decided to build them just below the lowest edge of the band to reduce losses.
Using a Youkit Antenna analyzer makes coils adjustments easier:
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My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
First try: hum, a bit to high in frequency. I need to add 2 or 3 more turns on the coil.
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My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
Now it is better, just below 10.100 MHz
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My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
And the one for 20m, on 13.800 MHz:
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My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
I've got all what I need now to build my trapped 40/30/20m EFHW:
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My Elecraft KX1 companion: an EFHW trapped antenna for 40/30/20m - 01-18-2016
by Phil - f5iyj's ham shack - http://f5iyj.com
to be continued.
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