[SECC] Upcoming activity

[Jay Pryor]

P.S.  How far apart are the elements?

- Jay, K4OGG

At 02:27 PM 2/6/2001, Gary Breed wrote:
> > Gary,
> >
> > Is the 2L 40 full sized or ??? Details ???
> >
> > TU !
> > 73 Billy AA4NU
>______________________________________________
>
>Here it is...Gary, K9AY
>
>
>Antenna description:  K9AY 2EL 40M Beam
>
>Boom: 18 ft. 2" OD x .093" wall
>
>Elements: 52 ft long; each side of center is 7 ft 1-1/2" tubing (insulated
>from boom), a 2-1/2" diam. loading coil (10-12 turns), 20 ft graphite
>fishing pole with 3/16" braid inside, less trimming and overlap.
>
>Weight: 25-30 lbs. max. No boom truss needed, not much element droop.
>
>Tuning: CW band, min. SWR at 7020, 1.5:1 at 7065, 2:1 about 7090.
>
>Matching: Direct feed with approx 50 deg. electrical length 25 ohm line (2x
>RG-8), driven element is theoretically 18 +j14 ohms. No balun - feedline is
>taped to boom, to the mast and routed on the inside of the tower. I think
>it's well enough isolated.
>
>Tune up procedure:  Started with EZNEC model.  "Disassembled" antenna in
>EZNEC to see that the reflector would be resonant by itself at about 6990
>kHz at 50 ft and driven element somewhat lower in frequency (remeber, it's
>inductive).
>
>Each element was assembled and raised on a rope and pulley for tuning.
>Loading coils were adjusted for desired resonance.  Loading coils lightly
>taped to allow future adjustment.
>
>Entire antenna was assembled and hoisted pointing upward until the reflector
>was about 20 feet off the ground.  The driven element was adjusted for 1:1
>match at 7025, which took four iterations of hoisting and lowering.  The
>match was 1:1, which inferred that the reflector was already tuned properly
>(Murphy cut me a break!).
>
>Mounted horizontally on the tower at 35 ft., the 1:1 match was at 7000.
>Raising the antenna to 75 feet raised the frequency to 7020 with about 1.1:1
>SWR.
>
>A few comments:
>
>1. Pre-tuning using modeled dimensions works well (I've done this before).
>2. Tuning with antenna at low height and pointing upward works well.
>3. Fiberglass or graphite crappie poles are great antenna elements (I did
>this before, too).
>4. I missed slightly on reflector tuning, but the error is on the side of
>gain rather than pattern -- I'll take it like it is!
>
>
>
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