Vectronics VEC-1862 - Manual (Page 5)

VEC-1862 Instruction Manual Six-meter Yagi Antenna
5
[ ] Temporarily fasten each "L" bracket to an end of the hairpin inductor with #6
hardware. The coaxial feedline will be connected to these points later on.
[ ] Temporarily install the mast-mounting hardware (U-bolt can go on either way).
This completes initial mechanical assembly. Check all fasteners for tightness.
FEEDLINE INSTALLATION
For coax runs up to 70 feet, we recommend using RG8M (or mini-8) 1/4" diameter foam
coax. This light-weight cable is available through most amateur radio dealers and is
available in Radio Shack stores nationwide. RG8M performs well at 50-MHz and will
handle 150 Watts with a reasonable margin of safety. Use the following steps to prepare
your feedline:
[ ] Strip back the outer insulation 1" and prepare the two conductors as pigtails--as
shown in the diagram below.
RG8M
Lugs
Sealant
[ ] Install a lug on each pigtail (crimp-type lugs should be crimped and soldered).
Pigtail length should not exceed 1-1/4"--including the lug. Excessively-long
pigtails will detune the matching system.
[ ] Apply 2-3 thin coats of Seal-All

to the exposed braid to retard water migration into
the cable. If Seal-All is not available, use a rubberized contact cement or a silicon
sealer. Allow sealant to dry thoroughly before handling the feedline.
[ ] Connect each coax pig-tail to a feedpoint stud using the #6 hardware provided (do
not use Locktite on these connections). Note that the hairpin is installed on the
bottom (or earthward) side of the boom. When installing the VEC-1862, the hairpin
should be on the ground side and your coax should drop directly below the hairpin.
BALUN
The VEC-1862 driven element is balanced. In order to prevent unwanted radiation from
the feedline, we suggest installing a balun at the feedpoint. This need not be an elaborate
or expensive addition--you can make a simple and effective choke-type balun using the
feedline itself. To do this, form a 5-turn coil of RG8M just below the feedpoint using
about 6' cable. Tape the coils together tightly with electrical tape and secure them to the
mast. As an alternative, install three (3) FB43-5621 ferrite cores on the feedline at the
feedpoint. Be sure to secure your feedline to the mast with electrical tape to provide
stress relief at the feedpoint.