Amateur Radio Station N4EKV
Antenna Tuners

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Balanced-L homebrew antenna tuner

  • Homebrew balanced-L antenna tuner.
  • Covers 160-10m. Designed specifically for balanced feedlines.
  • Inductors are cut from 100-turn 92uh B&W coil stock.
  • 20-500pf variable capacitor available new from Henry Radio. Can be switched from input to output of circuit with knife switch to match hi-Z and low-Z loads. (Builder's note: This cap is total overkill considering the wimpy input balun!)
  • Input balun consists of 17-turns of RG-58/U coax on an F-240-77 ferrite core available from CWS.
  • Base is a hardwood award plaque sourced from a trophy store for $15.
  • Nickname: "Frankie" after the V-shaped arcing contacts in the old Frankenstein movie.
  • Rear view.
  • Read L. B. Cebik, W4RNL's thoughts on Balanced-L Antenna Tuners
  • More Balanced L antenna tuner builder's notes

  • The removable "drawer" that allows band changes to be made via changing allicator clip positions on the coil.
  • Note "parking" terminals for the idle set of gator clips.

  • Front view of the coil assy, note the aluminum tabs that contact the rest of the circuit when the drawer is replaced.
  • The contacts are simple but effective: Braided wire rests on top of a 1/4" foam strip that is affixed just behind the tuner's front face above the 3 knobs. Upon replacing the drawer, the four aluminum tabs trap the braided wires agains the foam. Contact!
  • It took me quite a while to chart out clip and knob settings were when I first got this tuner! The high Q means that you have to retune every 25-50Khz on the lower bands.. but RFI suppression is great and the efficiency is unbeatable.
KW-107 Antenna Tuner

  • KW-107 SUPERMatch antenna tuner.
  • Z-Match circuit, very nice controls.
  • Rated at 100W contrary to the name. There was a KW-109 model that was supposedly rated for 1KW.
  • Inside view (where's the beef?)

  • LDG AT-11MP 200W auto tuner.
  • Works pretty well but I prefer the Antec for my doublet. The AT-11MP is destined for my mobile setup.
  • OOS (sold this equipment).

  • Ten-Tec AC5 tuner.
  • Link-coupled circuit.
  • 10W max.
  • Designed with no cover to allow easy access to gator clips.
  • Ten-Tec AC5 Antenna Tuner Operating Instructions PDF
  • Top view (Macro pic, 650K!).
  • Two AC5s. Note differences in rotor shafts and knobs. Original AC5 box and Ten-Tec AC5 manual.
  • Interesting tuner test done by W0RSP.
  • Now deployed at my office QRP station feeding a 200ft horizontal loop via TV twin lead up 35ft. Tunes 1:1 on all bands 6-40m and gets great reports!
  • Email Ten-Tec and tell then you want a 20W version for your new Argonaut V!

Rigs & Amps        Telegraph Keys

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