SWR / Power Meter
(210-0524)                 Operation                  Faxback Doc. # 33336

MEASURING STANDING WAVE RATIO

Follow these steps to measure your transmitter system's SWR.

1.  Set FUNCTION to CAL.

2.  Select a channel and press the transmit key on the transmitter.  Do not
    speak into the microphone while you make this measurement.

    Note:  If you use a CB that has side band modes, do not use the side
           band modes for this measurement.  If you have an amateur radio,
           use the CW mode to check the SWR.  See the ARRL Handbook,
           available at your local library, for more information about
           measuring SWR.

3.  While the signal transmits, rotate CALIBRATION until the meter's needle
    aligns with CAL.

4.  Set FUNCTION to SWR.

5.  Transmit a signal from the transmitter again, as in Step 2.

6.  Read the needle position on the SWR scale.

    If the transmitter's power is less than 20 watts, read the SWR L scale.
    For over 20 watts, read the SWR H scale.

    Refer to the next section to interpret the reading.

7.  Repeat Steps 2-6 for each channel or frequency you want to measure.

INTERPRETING THE READINGS

An ideal SWR reading is 1.0, or a meter reading of 1 on the SWR scale. This
measurement is possible only under laboratory conditions or with a dummy
load.  Actual antenna installations have higher readings. Use the following
chart to interpret the readings you obtain.

SWR               EFFICIENCY              INTERPRETATION

1.0 to 1.5        Excellent               The antenna cable and the antenna
                                          length match the transmitter's
                                          output requirements almost
                                          perfectly.

1.5 to 2.0        Very Good               The antenna, the cable and the
                                          transmitter operate very
                                          efficiently.

2.0 to 3.0        Acceptable              The antenna system easily puts
                                          out enough power for normal
                                          operation.

Above 3.0         Inefficient             Adjust your antenna or antenna
                                          mounting system to improve
                                          operation.

NOTE:  The SWR is different for different frequencies.  If you measure the
       SWR on several different channels or frequencies, you get different
       readings.  If you usually transmit on one channel more than the
       others, make your readings on the channel and fine-tune the system
       for that channel.  If you use all the channels without preference,
       make your readings on a channel centered within the band you use.
       For example, if you use all 40 CB channels, make your reading on
       Channel 19, because it is midway between Channel 1 and Channel 40.

The figures below the SWR values in the following chart indicate the
percentage of power that reflected back to the transmitter. For example, an
SWR reading of 1.5 also means that 4% of your signal power is lost.
However, 96% of the transmitter power is more than enough for almost all
applications.

SWR             1.0   1.1   1.2   1.5   2.0   2.5   3.0
REF POWER (%)   0     0.22  0.8   4.0  11.1  18.4  25.0

Improving the SWR Readings

There are three ways to improve your system's SWR.  Try the simplest first.

   Be sure you are using the cable recommended for your equipment.  If the
   manufacturer recommends a 50-Ohm cable, do not substitute another type
   that has a different impedance.

   Be sure that you mounted your antenna according to the manufacturer's
   instructions.  The angle and the base arrangement can affect the SWR
   reading.

   Adjust the length of your antenna according to the instructions provided
   by the manufacturer.  A change of 1/8 inch can make a measurable
   difference.

MEASURING POWER OUTPUT

Follow these steps to measure your transmitters power output:

1.  Set FUNCTION to POWER.

2.  Set RANGE to an appropriate position according to the transmitter's
    rated power.

    If you do not know the rated power, set RANGE to 2000W.

3.  If your transmitter is a single-sideband (SSB) or continuous-wave (CW)
    type, set the MODE switch to PEP to measure the peak-envelope power, or
    to AVG. to measure the average power.  See the ARRL Handbook, available
    at your local library, for more information on measuring power.

4.  Select a desired channel and transmit a signal.  Do not talk into the
    microphone during the measurement.

    If your transmitter is a single-side band type, to properly measure SSB
    output power connect a low-frequency oscillator to the transmitter, and
    input a 1000Hz-to-1500Hz tone signal from the oscillator.  This 
    procedure should be performed by a qualified technician.

5.  Read the needle position on the POWER scale.  The meter shows the
    forward power of the transmitter.

    When you set the RANGE switch to 20W, read the lower POWER scale.

6.  If the reading is extremely low within the selected range, set RANGE to
    a lower position and read the scale again.


(SP/EB 6/7/96)

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