Hy-Gain LJ-204BA Instructions

Starkville, MS 39759 USA

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INSTRUCTION MANUAL

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LJ-204BA

4-Element 20-Meter

HF Beam

General Description

The Hy-Gain Model 204BA-S is a close
spaced, 4-element, 20-meter beam. The
204BA-S is ideal for the 20 meter DX'er with
limited space or for your local club for field
day use. It is equipped with Hy-Gain's
exclusive Beta Match, rugged boom-to-mast
brackets and stainless steel hardware for all
electrical and most mechanical connections. It
is designed to fit mast sizes from 1 1/4" to 2
1/2" and can be rotated with Hy-Gain's CD­45 II or HAM IV Rotators.

WARNING

When installing your antenna system,
take extreme care to avoid any accidental
contact with powerlines or overhead
obstructions. Failure to exercise this care
could result in serious or fatal in

Dimensions are included to scale this antenna
to the new 17 m (18 MHz) band. All
electrical specifications are identical to those
shown below.

.

*Gain, Front-to-Back Ratio, and Beamwidths verified by the MININEC 3' Computer code along with radiation

attern measurements of full size antennas on Hy-Gain's test range.

Preparation for Assembl

y

Assembly of the Boom

FOR OUR OVERSEAS CUSTOMERS: The
United States uses American units of measure­ment. Please see the last page of this manual
for assistance in identifying the hardware and
components used with this product.

Choose a large, clear area to assemble the
204BA-S. The area must be at least 26'x 37' (8
m x 11.5 m). When unpacking your antenna,
check inside of all tubing for parts. To
conserve space, these smaller articles are
sometimes put inside larger pieces. Check all
parts against the parts list to ensure no parts
are missing.

All tubing supplied with the 204BA-S tele­scopes together. Make all measurements to the
given dimensions, plus or minus, no more than
one eighth (1/8) inch.

Select the two formed boom clamps (Item 6
and 7) and loosely assemble onto the two
center boom sections (Item 16), using four of
the 1/420 x 3/4" bolts (Item 28), 1/4-20 nuts
(Item 33), and 1/4" lockwashers (Item 32), and
two of the 5/16-18 x 2 3/4" bolts (Item 35),
5/16-18 nuts (Item 40), and 5/16" lockwashers
(Item 39). Refer to Figure 1.

If available, drive a temporary mast into the
ground in the center of a large, clear area. At­tach the two cast aluminum brackets (Item 1)
to the temporary mast at a convenient height,
using two of the 5/16-18 x 3 1/2" bolts (Item

36), 5/16-18 nuts (Item 40) and 5/16"
lockwashers (Item 39).

Attach the boom assembly to the cast brackets
on the temporary mast using four of the 5/16­18 x 5" bolts (Item 37), 5/16-18 nuts (Item

40), and 5/16" lockwashers (Item 39). Tighten
all hardware. Refer to Figure 1.

Install the two outer boom sections (Item 5) as
shown in Figure 2. Tighten these two bolts at
this time. Install the two black caplugs during
final assembly.

Driven Element Detail Reflector-Director Deta il

Figure 3 Element-to-Boom
Brackets

Assembly of the Driven Element

prop

and Beta Match

Select a set of large sized element-to-boom
brackets (Item 4) and loosely assemble on the
Reflector end of the boom, approximately 31
5/8" from the center of the boom-to-mast
bracket. Refer to Figure 3, 4, and 7.

NOTE: The following steps will have to be
done first for one side of the boom, then
repeated for the other side.

Select the parts listed in Figure 4 and Detail
A and assemble them as shown. The beta
shorting clamp should be flush with the ends
of the beta rods. After attaching your coax
cable to the feedpoint, tighten all hardware

NOTE: Do not allow the beta rods or coax
cable leads to touch the element-to-boom
bracket.

Check to see that the Driven Element will lie
in a plane parallel to the earth, then tighten
the anchor screws (Item 27) in the bracket

Select the DE1 section of tubing. Slip the
thick walled end (end with extra strength
tubing inside) of the DE1 into a Driven
Element insulator as shown in Figure 3. Slip
the insulated end of the DE1 into the bracket
assembled on the boom. Tighten the bolts to
hold the element securely, but do not tighten
the anchor bolts (in the center of the bracket)

Select a # 16 tubing clamp (Item 22) as
shown in Figure 5.

NOTE: Figure 5 shows all the clamps and the

er way to align them on the tubing.

Slip the #16 tubing clamp (Item 22) over the
end of the DE1 section. Select the DE2
section and slip the unswaged end into the
DE1 section. Adjust to the dimension shown
in Figure 7, then tighten the clamp securely.

Installation of Tubing Clamps

Select the proper si ze tub ing cl amp as shown
in the chart. When installing the clamps, place
the clamp near the tube end with the top of
the clamp over the slot in the tube as shown in
Figure 5.

After adjustment of the t ubin g lengths, ti ghten
the clamp with a nut dri ver, s ocket , or op en
end wrench until the tubin g will not twist or
telescope.