Element Assembly
To take advantage of the broadband nature of
the TH7DX, use the supplied dimensions as
shown in Figure 6. If assembled correctly, the
VSWR will be below 2:1 on any frequency on
these 3 bands. However, if you wish to
optimize the TH7DX for the DX portions of
these 3 bands, use the following "DX setting"
for the RDE-2 and FDE-2 dimensions:
RDE-2 = 33" (83.8 cm)
FDE-2 = 42" (106.7
Use 10-meter trap, Part Number 878749, and
15 meter trap, Part Number 878637, in this
assembly. Make sure all insulators and trap
caps are firmly seated.
NOTE: The drain holes and slots should be
facing the ground and the trap labels should
be on the boom side of the trap. Also, on all
tubing attached to traps, make sure all slots
are facing the ground and the small drain
holes are aligned with the slots. See Figure 5.
The DX setting will result in minimum
VSWR at 14.150, 21.260 and 29.000 MHz.
However, VSWR near 14.350 and 29.700 may
be slightly above 2:1. The front-to-back ratio
and gain will not change.
The following steps will be in singular form.
Do each element assembly step, first for one
side of the boom and then for the other side.
The dimensions shown in Figure 6 are in
English units on the right side and metric on
the left side. After each. element is assembled
to the boom, tighten the eight (8) 1/4"-20 x
3/4" bolts (Item No. 34). After all elements
are assembles, make sure that they all lie in a
horizontal plane, then tighten the anchor bolt
Front Driven
Select the FDE-1 section (1 1/4" x 35") and a
driven element insulator (see Figure 3). Slip
the DE insulator on the unslotted end of the
FDE1, then slip the insulated end of the FDE-
1 into the bracket which is 20 inches to the
left of the mast bracket. Tighten the eight (8)
bolts to hold the element in place.
Install a No. 16 tubing clamp on the slotted
end of the FDE-1 and insert the unslotted end
of the FDE-2 (11/8" x 48") to the dimension
shown in Figure 6. Tighten the No. 16 tubing
clamp securely and recheck the FDE-2
Assemble the remainder of the Front Driven
Element in the same manner using
dimensions from Figure 6. Use Figure 5 and
Detail A as guides.
Rear Driven Element
Select the RDE-2 section (1 1/4" x 48") and a
driven element insulator. Slip the DE
insulator on the unslotted end of the RDE-1,
then slip the insulated end of the RDE-1 into
the bracket which is 35 inched to the right of
the mast bracket. Make sure the insulator
seats completely onto the tube and into the
bracket. Tighten the eight (8) bolts to hold the
Install a No. 16 tubing clamp on the slotted
end of the RDE-1 and insert the unslotted end
of the DRE-2 (11/8" x 36") to the dimension
shown in Figure 6. Tighten the No. 16 tubing
clamp securely and recheck the RDE-2
dimension. Assemble the remainder of the
Rear Driven Element in the same manner
using dimensions from Figure 6. Use Figure 5
and Detail A as guides. Use the same traps as
on the Front Driven Element.
10-Meter Reflector Element
Select the R2-1 section (7/8" x 55") and slip
the unswaged end of the R2-1 completely into
the bracket (Item No. 83) assembled on the
boom 58 1/2" inches to the right of the RDE.
Tighten the eight (8) bolts to hold the element
onto the boom
Assemble the remainder of the 10-meter
reflector as shown in Figure 6 using No. 6
tubing clamps. Tighten all element tubing
clamps with the slots facing the ground and
recheck all dimensions.
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