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B. TUNING YOUR ANTENNA WITH AN SWR METER
Using an SWR meter is the most accurate way to tune an antenna. Connect the
SWR meter as close as possible to the back of the transceiver. Use a double male
connector or a very short piece of RG58/U with connectors on each end.
Place the adjustable whip halfway into its receptacle. Set your transceiver to Channel
20. Measure the SWR following instructions supplied with the meter. After the first
measurement, move the whip down 1/8 to 1/4 inch and repeat ALL the steps again.
If the SWR is lower, continue the process moving the whip down 1/8 to 1/4 Inch at a
time until'the lowest reading is obtained. If the SWR is higher, raise the whip 1/4 to ½
inch the first time and 1/8 to 1/4 inch thereafter until the lowest SWR is obtained.
Note, if the reading continues falling but you have reached farthest point down that you
can go with the whip, the whip may be too long. To verify this, put the Channel Dial to
Channel 1 and measure the SWR. Next, put the channel dial to Channel 40 and
measure the SWR.
IF THE SWR WAS LOWEST ON CHANNEL 1 AND HIGHEST ON 40 THE WHIP
SECTION IS TOO LONG.
Carefully cut 1/4 to 3/8 inch from the whip section and re-measure Channels 1, 20,
and 40. If the SWR is still lowest on Channel 1 continue trimming the whip by
removing 1/8 to 1/4 inch at a time until the lowest SWR is obtained on Channel 20.
DO NOT GET OVERANXIOUS. YOU CANNOT REPLACE A SECTION ONCE IT IS
CUT OFF.
If you exceed slightly the best tuning for Channel 20, the whip may be raised 1/8 to
1/4 inch at a time to obtain the best SWR on Channel 20.
WARNING: DO NOT CUT THE WHIP USING THE "POWER OUTPUT METER
TUNING METHOD" YOU MUST USE AN SWR METER TO ACCURATELY DETERMINE
THE SWR.
Every six months or so, re-check the SWR. Car washes, road grim, and chemicals
can effect the mechanical connections of an antenna and corrode them. This corrosion
can cause poor electrical connections and lead to high SWR. The correction of this
problem is usually accomplished by cleaning of the metal connection parts with a
wire brush.
