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Random / long wire antenna

Random wire antenna, a.k.a. long wire antenna

Both a 9:1 unun and a 1:1 RF choke is used for the random wire antenna.

9:1 unun and RF current choke:

  • 9:1 unun - an attempt to impedance match random / long wire antenna - transforming 50 ohm impedance to 450 ohms.
    For more info on ununs, search the web for: 9:1 unun or 1:9 unun.
  • RF current choke - to reduce or eliminate feedline radiation due to common mode current flow.
    For more info on RF current chokes, see the "ugly balun" web page.
Choke and unun are mounted on a ChoiceDek Foundations Beach House Grey composite deck trim board (3/4" x 11-1/4" x 3').  The choke and unun were not mounted too close to each other to prevent any unwanted electro-magnetic coupling. Ground cable with tent stake is bolted to Diamond SP1000 lightning surge protector (installed between choke and unun).

Current antenna setup:  ~55' of 14 AWG stranded insulated wire (oil and gasoline resistant), driven vertically ~7' then horizontally sloping slightly 7' to 15' above the ground to suspended insulator end.  Single counterpoise wire (radial) on the ground roughly parallel underneath the aerial (about 25' long using similar wire).  Tunes up ok (SWR <1.7) on most bands from 80m to 10m - adjusting length of either aerial or counterpoise may be required for optimizing the desired operating band(s).

9:1 unun (unbalanced to unbalanced 50 to 450 ohm) impedance transformer:

1st version - KO6PY now has this project I made

10 turns of 14 AWG enameled wire (trifilar winding) on Amidon T200-2 core, using a Amidon AB200-10 kit.

2nd version

6 turns of 14 AWG enameled wire (trifilar winding) on A-094033 / MP-225026-2 core (the eyelet is used as a wire strain relief, and the actual antenna contact is to the wing nut).

The plastic boxes shown are Cantex 4" x 4" x 2" electrical junction boxes. Stainless steel hardware is used for the antenna and ground connections.

HF 1:1 RF current choke

The plastic box shown is Cantex 6" x 6" x 4" electrical junction box.

Choke inside view:

20' of JSC mini-8/U #3060 wound around a 4" ABS pipe coupling.  Inset photo is close-up of connector on right side.

Choke outside label:

Coax connection sealed with silicon wrap.

HF 1:1 RF current air choke

To eliminate feedline radiation - intended for 15 or 20 meters (1st version).

11 to 12 turns of RG-58/U coax on a 3.5" diameter PVC pipe coupler, ~ 13' of coax, connector-to-connector:

Cable tie wraps holding the coax in place: