Tuning The Antenna For Optimum Swr - Midland 8001 XT Manual Del Usario

direction of the body of the vehicle. For all pratical purposes, however, the radiation pattern
is nondirectional. The slight directional characteristic will be observed only at extreme
distances. A standard antenna connector (type SO 239) is provided on the transceiver for
easy connection to a standard PL 259 cable termination. If the transceiver is not mounted
on a metal surface, it is necessary to run a separate ground wire from the unit to a good
metal electrical ground in the vehicle. When installed in a boat, the transceiver will not
operate at maximum efficiently without a ground plate, unless the vessel has a steel hull.
Before installing the transceiver in a boat, consult your dealer for information regarding an
adequate grounding system and prevention of electrolysis between fittings in the hull and
water.

TUNING THE ANTENNA FOR OPTIMUM SWR

Since there is such a wide variety of base and mobile antennas, this section will strictly
concern itself to the various types of mobile adjustable antennas. Because the antenna
length is directly related to the channel frequency, it must be tuned to resonate optimally
all 40 channels of the transceiver. Channel 1 requires a longer antenna than Channel 40
because it is lower in frequency. Due to the various methods of adjusting antennas for
proper SWR we have chosen what we think is the optimum method:
A. Antennas with adjustment screws (set screws).
1. Start with the antenna extended and tighten the set screw lightly enough so that the
antenna can be lightly tapped with your finger for easy adjustment.
2. Set your transceiver to Channel 2.0. Press the PTT (push-to-talk) switch, and tap
the antenna (making it shorter). The SWR meter will show a lower reading each time
the antenna is tapped. By continuing to shorten the antenna you will notice the SWR
reading will reach a low print and then start rising again. This means that you have
passed the optimum point for Channel 20. Adjust the antenna and again follow the
procedure above.
B. Antennas which must be cut to proper length.
1. Follow the same procedure as above, but adjust the length by cutting 2/3 mm increments
until a good match is obtained.
2. Be very careful not to cut too much at a time, as once it is cut, it can no longer be
lengthened.
3. The whip is easily cut by filling a notch all the way around and breaking the piece off
with pliers.
If you are having difficulties in adjusting your antenna, check the following:
A. All doors must be closed when adjusting the antenna.
B. Make sure the antenna base is grounded.
C. Check your coaxial cable routing (it may be pinched when routed into the car).
D. Try a different location on your car (keeping in mind the radiation pattern you wish).
E. Is the antenna perfectly vertical?
F. Try a different location in your neighbourhood. Stay away from large metal objects when
adjusting (metal telephone or light posts, fences etc.)
WARNING: The transceiver will operate into a SWR of 2 to 1 indefinitely and sustain a
SWR of 20: 1 for a maximum of 5 minutes at rated operating conditions.
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