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Page 67
CHAPTER NINE
SECTION 9.0
OPTIONAL 6M PASSIVE ELEMENT KIT
While the DB18 has a 3 element 6m Yagi that is standard, the spacing is a bit wide so gain is compro-
mised and there is reduced front-to-rear. For the average 6m user, this configuration works just fine,
with gain of 6.2 dBi and front-to-rear of 4 dB. Adding the optional 6m passive elements creates a nice-
ly performing 4 element Yagi, with gain of 10.1dBi and front-to-rear of 30dB. As with any fixed length
element, there is a limit to the effective frequency range— you can expect the optional 6m passive
elements to function well in 50.00 MHz to 50.400 MHz frequency range, but there will be no 180 de-
gree or bi-directional mode for the DB18 when operating on 6m. In addition, you will need to rotate it
like a traditional Yagi for this band only.
The passive element consists of three sections of polished aluminum—a single 58” long x 1/2” OD cen-
ter piece with plastic insulator, and two 36” long x 3/8 OD sections that telescope into each side of the
1/2” OD aluminum. The 1/2” aluminum has slotted ends, so that a stainless steel hose clamp can se-
cure the two sections firmly together.
Using a measuring tape as shown in
figure 9.02
, measure the 3/8” aluminum pieces and mark with a
permanent ink pen the length required for the 6m passive element as shown in
table 9.01
.
Telescope the 3/8” aluminum sections into each end of the 1/2” aluminum section. Place the stainless
steel hose clamps (PN 60-6000-60) over the slotted portion of the joint as shown in
figure 9.03
. Tight-
en enough to hold the pieces in place but loose enough to adjust if needed. Measure the overall length
of the 6m passive element as shown in
figure 9.04
. If the element is the required length, tighten the
stainless steel hose clamp firmly on each side.
PREPARING THE 6M PASSIVE ELEMENT
6m
Passive
element
Total
Element length
3/8” Aluminum length to
reach total length
(per side)
D1A
112 inches / 284.5 cm
27 inches / 68.58 cm
FIG. 9.01
FIG. 9.02
FIG. 9.03
FIG. 9.04