Slide the bars onto the 3/16” rod driven element tips and the 1/4” Driven Element Block Rods
.
Position the Shorting Bars as per the DIMENSION SHEET. Then align the bars and rods with each other
and tighten the setscrews.
9. Refer to Hardware Drawing. Attach the square 18” RISER TUBE to the boom-to-mast plate using two 8-32 x
1-1/4” screws and locknuts. The large holes at the top of the riser are slightly off-center and should be
oriented away from the boom-to-mast plate and closer to the centerline of the boom.
10. The boom to mast plate is normally mounted at the balance point, about 15’ 10” from rear of boom. Since
the feed line represents significant weight it is best to have it attached and fastened along the boom with
cable ties before final mounting the plate. Use two 1-1/2" U-bolts and the stainless nuts and lock washers
provided. DO NOT OVER TIGHTEN. 2” U-bolts are provided for mounting the antenna to your mast.
11.
Install a small “U” shaped rod into the top side of the rear 1” boom section and the front 1-1/4” boom section.
Secure with keepers.
12. Install the two turnbuckles into the top of the riser with open ends of the hooks “UP”. Adjust threads until just
one or two show inside turnbuckle body. Adjust the boom with supports until the middle is 4” to 6” LOWER
than the ends. Attach one end of the Dacron cord to the rear U clip by taking two wraps through the “U” and
finishing with two half-hitches or a square knot. Adjust to leave 2” to 4” of cord after knots. Attach the other
end of the cord to the front clip in the same way. Equalize excess cord at the riser tube and cut. Take rear
cord end and make two wraps through rear turnbuckle eye, then pull line taut and knot as above. Repeat for
front cord and turnbuckle, balancing tension.
13. Now support antenna at the boom-to-mast plate. This tensions the cord and helps the knots to take a set. If
possible, let this process extend overnight. Then adjust turnbuckles so boom ends bow up slightly (and
equally). A few days on the mast should leave the boom straight. Cut excess lengths from cord, leaving 2” to
4”. To prevent fraying melt ends with heat or flame and tape back to main line.
THIS COMPLETES THE ANTENNA ASSEMBLY.
INSTALLATION AND STACKING INFORMATION
A. Never mount the antenna with a metallic mast or crossboom in the element plane: pattern and
performance will deteriorate.
FOR HORIZONTAL POLARIZATION, the antenna may be mounted to a
metallic vertical mast or a horizontal NON-METALLIC / NON-CONDUCTIVE crossboom . If mounted to a
horizontal crossboom, route the feedline forward to the boom-to-mast plate, loop down, and bring back to
crossboom at least 6” beyond element tips. Antenna pairs are typically stacked one above the other in
horizontal polarity.
H plane stacking distance is 13 to 14.5 ft.
See Stacking Reminders, below.
B
. To optimize the performance from this high quality antenna, always use high quality coax and
connectors, as old, corroded, or poor quality materials are common sources of SERIOUS performance
losses.
C.
If possible, test the antenna, connectors and feedline BEFORE installing to your mast or tower. At
6 feet or more the antenna will exhibit VSWR
similar to
higher mounting heights. Set antenna on a ladder or
temporary mast. Check for continuity and that the match is close to the rated specifications. It should be
1.5:1 or better from 144 to 146 MHz. Remember, the 2M18XXX is tailored for the lower half of two meters
where horizontal polarity and Single Side Band (SSB) / CW are the common modes.
C. STACKING REMINDERS:
1. All driven element blocks MUST be oriented to the same side of boom.
2. All boom-to-mast plates MUST be mounted at the same point on the boom.
3. Feed / phasing lines MUST be of equal electrical length or multiples of 1 wavelength in order to
maintain equal phasing in the array. Improper phasing can severely deteriorate performance.
DESCRIPTION
QTY
2M18XXX ASSEMBLY MANUAL
Содержание 2M18 series
Страница 4: ...2M18XXX DIMENSION SHEET...
Страница 5: ...2M18XXX ASSEMBLY DETAILS...
