End fed half wave antenna 40/30/20m

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Last Updated: Tuesday, 08 December 2020 06:13

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For my SOTA activities, i recently bought a QRP transceiver QRP SW-3B, which is a three-band QRP CW only for 40/30/20 m.
So, i needed an antenna that would allow to use these 3 bands in SOTA portable activity.
Already having some experience with the EFHW antenna, i decided to build one for 40/30/20m.
The main advantages of this EFHW antenna are :
- easy to build
- multiband
- needs only one support, can be installed in line, inverted V,  zigzag.
- fed at its extremity, can be directed connected to the transceriver, without any coaxial cable.
- the radiating part is at the center
All these advantages are welcome for portable operations and make this antenna a perfect candidate for SOTA

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Cushcraft traps repairing.

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Last Updated: Friday, 28 February 2020 22:59

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I used the Cushcraft A3 et A4s yagis and soon or later, problems are appearing..
Here are the results of my investigations and repairing technic, that can be applied to other models and trades as well.
What is described here applies to a A4s triband antenna, but the reasoning can be made for any multi-band yagi or vertical.

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Universal K3NG rotor interface PCB

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Last Updated: Friday, 18 January 2019 14:58

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Description of a PCB, also called "shield" allowing to build a universal rotator interface based on the K3NG software. Only the AZIMUT function is supported.
This PCB has been thinked to be used either with a LCD display or an Ethernet shield to allow a remote usage via IP, and for a rotator using a variable resistor for the azimut value .  (HAM IV or CD44 in my case)

The board includes :
- a 5V/1A regulator
- a header to plug an Arduino UNO and an Ethernet shield
- a HE10 male connector for to LCD display with a ribbon cable 
- a 5 pin DIN connector (+ ground shell) to connect the rotator control box
- 2 connectors for the "Clockwise" and "Counterclockwise" pushbuttons
- a multi-turn ajustable resistor VR2 for the azimut calibration
- an ajustable resistor VR1  for the LCD contrast
- 3 transistors for the CW, CCW, and BRAKE commands (open collector outputs)

I still have some naked pcb boards left. If interested, please feel to contact me.

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