Re: Home-brew magnetic loop
Charles W. Powell
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Not a problem Jim. I have sent this enough times that I just need to copy and paste. This tunes and radiates well on 17 & 20 meters. Tunes well and radiates fair on 30 meters. Tunes well and radiates poorly on 40 meters. 9’ is a good length for 15-17, with some compromise on 20 meters, and 6’ is a good length for 10-12 meters, with a compromise on 15. Coupling loop is 20% of the full sized loop.
Chas - NK8O
Dimensions and materials
12’ LMR-400 for the main loop
2.4’ of copper tubing
Capacitor salvaged from an old Denton tuner that no longer worked
Electrical box for the capacitor
Various SO-239 connectors
1/2” schedule 40 PVC
Station in a bag (18” long)
Antenna parts in the bag
Laid out, ready to assemble
The base, assembled. I now use a shorter extension for better stability.
Laying out the main loop.
And connecting the capacitor. Shield only. Inner connector is not used.
Ready to make QRM from Riverside Park, Scottsbluff NE
And the rest of my station - KX3/PX3, Macbook Air, 4.6 Ah LiFePO4 battery
Me with the loop
Capacitor detail. Ideally, an butterfly or vacuum variable is superior.
Coupling loop mounting details. This is “new and improved” over the one pictured above.
12 gauge wire was used, soldered to the tubing after crimping, and the whole assembly pulled in as tight as possible.
SO-239 then soldered into place on the center post, and held with a screw and nut on the “ground" side.