K6ARK Antenna Kit
17 Feb 2022 Ralph AB1OP
K6ARK Adam is an active SOTA QRP operator. He has developed a small QRP Antenna (Matching) Kit currently sold on Amazon. The kit comes with your choice of either a Male or Female BNC connector as the feed point.
On his web site he has instructions of how to build the kit in one of three different configurations;
1) 49:1 UnUn for EFHW End Fed Half Wave
2) 9:1 UnUn for EFRW End Fed Random Wire
3) 1:1 BalUn for a Dipole.
Website: https://k6ark.com/
My Build: A 9:1 UnUn for EFRW antenna
I decided to purchase a male BNC kit. I need to modify the kit
to handle the maximum power my Xiegu G90 can produce (20W). I will build it as a 9:1 UnUn for a EFRW antenna to take advantage of the G90 built in ATU.
to handle the maximum power my Xiegu G90 can produce (20W). I will build it as a 9:1 UnUn for a EFRW antenna to take advantage of the G90 built in ATU.
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| K6ARK Kit (Male BNC Version) |
K6ARK Adam suggested for G90 use, adding an FT82-43 toroid to nest the FT50-43 toroid into. The combined toroids would increase the power handling to 30 Watts.
Adam offered to send me additional 26 AWG magnet wire since the kit supplied 28.25 inches of wire. I had plenty on hand from other projects. I calculated I need at least 36 inches, I cut off 40 inches from my stock as insurance.
Replaced the 3/4 inch heat shrink tubing supplied in the kit with a 1 inch diameter piece of heat shrink tubing and added some additional small diameter pieces to tubing as needed.
I also purchased some 2mm banana connectors to attach the radiating and counterpoise wire elements.
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| Additional pieces to modify kit for my G90 The female BNC was used as a heat sink when soldering the male BNC Notice the 3.5X reading glasses |
Following K6ARK instructions from his website I was able to complete the kit.
I did have to bring out the "helping hands" to hold on to the PCB while soldering.
a) Soldered the radiating and counterpoise leads to the PCB and pulled the leads thru the strain relief holes provided in the PCB.
b) Wind the 10 turns, twist a tap, wind 20 turns on the combined toroids.
c) Burned off the enamel on the three toroid leads. Arrange the leads to match the holes in the PCB and solder.
d) Tilt the toroid windings and solder the male BNC to the PCB.
e) Shrunk Tubing over the assembly to cover and protect the windings.
f) soldered 2mm banana connectors on the short wires for antenna and counterpoise wires.
I also soldered 2mm banana connectors on a 41 foot 26 awg wire for the antenna and on a 17 foot 26 awg wire for the counterpoise. I shrunk red HS tubing on the antenna connectors and black HS tubing on the counterpoise connectors.
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| Complete EFRW antenna on a 1/2" PVC wire winder The short PVC sections can be detached and used as insulators |
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| HB EFHW compared to K6ARK EFRW Green spool of support cord and UHF(PL-259) to BNC(female) adapter is common to both |
HB EFHW consists of
a) 49:1 UnUn based on a ft140-43 toroid in project box with a female BNC.
b) ~66 feet of 18 awg wire on a 9" spool.
c) 25 foot RG-8X coax with BNC male to male.
d) Large insulator to tie antenna wire to support cord.
e) UHF(PL-259) to BNC(female) adapter.
f) 100 foot spool of strong cord for support line.
K6ARK EFRW consists of:
a) 9:1 UnUn based on a combined ft50-43 & ft83-43 toroids on a male BNC kit.
b) 41 feet 26 awg wire.
c) 17 feet 26 awg wire.
d) 1/2" PVC wire winder, one of the short pieces can be detached and used as an insulator to tie the antenna wire to support cord.
e) UHF(PL-259) to BNC(female) adapter.
f) 100 foot spool of strong cord for support line.
In Conclusion: With Adam K6ARK antenna matching kit you have the smallest, lightest feed point connector possible, you can leave the heavy coax cables and large gauge antenna wire in your shack. If portable QRP operation is your thing whether atop a mountain summit, sitting of a park bench or just hanging out in your backyard you will enjoy using this kit.
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