Hy-Gain DX-88, Инструкция по эксплуатации

Страница: 19 / 30

TUNING THE DX-88
VERTICAL ANTENNA
Decide if you want to tune the DX-88 vertical
for the 8 HF amateur bands or whether you
wish to tune it for reception on the
international shortwave broadcasting bands.
Also, if you choose the amateur band settings,
you must also choose a setting for either 80
meter CW (3500 - 3800 KHz) or 75 meter
"phone" (3700 - 4000 KHz). Although the
DX-88 may be tuned from 3500 to 4000 KHz
at the base of the antenna, the narrower 40
meter band (7000 - 7300 KHz) tracks along
with the same adjustment. The 5/8 inch tubing
near the tip of this antenna (dimension I)
should be set to 18 inches if you operate
mostly on CW on both 40 and 80 meters.
Dimension I should be set to 28 inches if you
operate mostly on phone on both 40 and 80
meters.
If you wish to use a tuner or matchbox to
cover all of the 80 meter band, choose either
the CW or phone setting and tune the long
capacitors to favor the right part of the 40
meter band. You may then switch the tuner to
the "thru" setting for 40-10 meters.
You may install the DX-88 on the ground, on
a rooftop or on a mast. If installed on the
ground, the supplied dimensions will be
accurate only if the GRK-88 ground radial kit
is used, or if a radial system is constructed
identical to the GRK-88. Each of the bands,
30 meters through 10 meters, may be tuned
individually to favor a particular part of each
band. On 30 meters, dimension H may be
lengthened to lower the resonance or
shortened to raise the resonance on each band.
On the other bands, more capacitance (tubing
pushed in) will lower the resonance, and less
capacitance (tubing pulled out) will raise the
resonance.
If installed on a rooftop, the supplied dimen-
sions will be accurate only if the RRK-88 roof
radial kit is used or if a radial system is con-
structed identical to the RRK-88. Each of the
bands, 30 meters through 10 meters, may be
tuned individually as described previously.
Also, each band may be tuned by adjusting
the lengths of the corresponding radials.
This may be easier to achieve on some roof
tops. Mast mounting is the same as roof top
mounting.
A radial system is always required with this
antenna. The only exception might be when
the antenna is installed on a saltwater beach
with a ground rod.
If you choose to tune the DX-88 for SWL
operation, you may optimize the antenna for 8
bands. Other bands of frequencies may still be
received by this antenna, but at reduced signal
strengths. Adjust dimensions A through T
according to these tables and graphs or from
the dimensions supplied in the examples. See
Figure 12.
EXAMPLE I - Amateur
The dimensions for this antenna to resonate
in the center of each amateur band are:
EXAMPLE 2 - SWL
The dimensions for this antenna to resonate
in the center of the 11, 13, 16, 19, and 31
meter SWL bands, and near the 49 and 90
meter SWL bands are: