INTRODUCTION
Your CB/Ham Field-Strength SWR Meter helps you tune your CB or amateur radio system for the best performance.

CB and amateur radio systems work best when the antenna system's impedance matches the transmitter's output impedance as closely as possible. The meter's standing wave ratio (SWR) function helps you trim your antenna to the precise length you need for the maximum transmitted power.

The meter's field strength function helps you position your antenna for the best coverage and determine the effectiveness of changes you make to your antenna, antenna cable, and transmitter.

Measuring SWR shows you how much of your radio's transmit power is reflected from the antenna back into the antenna cable, generating heat and wasting power. With this information, you can adjust the length of your antenna or antenna cable so your antenna and radio combination can produce the maximum power they are capable of producing.

To connect this meter to your CB or amateur radio and your antenna, you need coaxial cable ( 50 ohm such as rg-8x) with a PL-259 connector on both ends . The cable must reach from the back of the meter to your radio's antenna jack.

Follow these steps to connect the meter to your radio and antenna.

1. Turn off your radio. Then disconnect the antenna from the radio and plug it into ANTENNA on the back of the meter.

2. Plug the coaxial cable into the radio's antenna jack and into TRANSMITTER on the back of the meter.

1. Set CALIBRATION/FS/SWR on the front of the meter to CALIBRATION/FS.

2. Turn on your radio. Then select a channel or frequency on your transmitter and hold down its transmit key. Do not speak into the microphone.

Notes: An SWR reading will be different for different frequencies (channels). If you transmit on one channel more often then any other, select that channel. If you transmit on several channels, choose a frequency in the middle of the range of channels you use. (For example, if you transmit on all 40 CB channels, choose Channel 20, because it is midway between Channel 1 and Channel 40.)
If you use a CB that has sideboard modes (SSB), do not select any of these modes. (Use only AM for SWR measurements).
If you have an amateur radio, select the continuous wave (CW) or tuning mode to check the SWR.

3. While you hold down the transmit key, rotate the meter's knob until the needle points to CAL.

4. Release the transmit key, then set CALIBRATION/FS/SWR to SWR.

5. Press the transmit key again, then read the SWR by noting the needle's position on the upper SWR scale. A meter reading of 1 on the upper scale is ideal.
The figure shown between the upper and lower scales on the meter (% REF POWER) indicates the percentage of power that is wasted through reflection of the signal from the antenna back into the antenna cable. For example, an SWR reading of 1.5 also means that 4% of your signal power is lost. However, 96% of the radio power is more than enough for almost all applications.

6. Repeat Steps 1-5 for each channel or frequency you want to get an SWR reading for.

An ideal SWR reading is 1.0, but this reading is usually possible only under laboratory conditions or with a dummy load. Actual antenna installations have higher readings. The information below will help you interpret the readings you get.

SWR / Efficiency / Interpretation

1.0 to 1.3 Excellent The antenna cable and the antenna length match the transmitter's output requirements almost perfectly. (Most desireable for power applications)

1.3 to 1.8 Very good The antenna, the cable, and the transmitter operate very efficiently.

1.8 to 2.2 Acceptable The antenna, the cable, and the transmitter operate with some loss. If possible, adjust your antenna or antenna mounting system to improve.

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

There are several ways to improve the SWR of your radio/antenna combination. Try these first.

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

Confirm 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 as little as 1/8 inch can make a measurable difference.

Your meter can measure the low levels of radio frequency (RF) generated by a radio transmitter. You can use these measurements to map the transmitting direction and coverage pattern of your antenna, or to compare your radio and antenna's efficiency before and after an adjustment. You do not need to connect the meter to the antenna or the radio to measure field strength.

It takes two people to measure field strength. For an accurate measurement, you will need to map the site around your antenna. Then, while someone presses the radio's transmit key, you will need to walk around the site around your antenna with the meter, marking the readings you see.

Several photocopies of the template

36 objects such as rocks or weighted pieces of paper

25 feet of rope or strong cord

Calculator

Pencil

Compass

Make sure there is at least 25 feet of open space in all directions around your antenna.

Before you use the meter to measure field strength, you should mark the site around the antenna in a pattern that will help you make the measurement.

An easy way to do this is to map the area around your antenna.

The template shows an imaginary circle around an antenna, with the circle divided by 18 spokes representing imaginary straight lines measured from the center of the circle to 36 points spaced equally around the circle. Each straight line is 25 feet in length. Four equidistant concentric circles are drawn between the center and the outside circle. The circles are numbered from 1 (the circle closest to the center) to number 5 (the outside circle). The numbers on the template (1-5) are a guide to show your where to mark the field strength level the meter displays as you measure.

Hint: To help measure to a circular path around the antenna, tie a slip knot in a 25-foot piece of rope or strong cord, slide the knot loosely around your antenna then use the rope as a guide as you walk around the antenna.

1. Starting at the antenna, use a compass to find due north. Then walk due north and stop about 15 to 25 feet away from the antenna.

2. Use an object such as a rock or a weighted piece of paper to mark where you are standing.

3. Walk around the antenna in a circle, using more objects to mark 35 more evenly spaced marks on the path.

Hint: You can quickly find the space to leave between each mark by using a calculator. Measure the diameter of the marked circle (from one side of the circle to the other). Then, divide the diameter by 11.46.

IMPORTANT: Be sure to follow any radio service regulations that limit the amount of time you can transmit without a break or station identification.

1. Use supplied antenna for the meter.

2. Set CALIBRATION/FS/SWR to CALIBRATION/FS.

3. To calibrate the meter, have your helper select a channel or frequency on your transmitter and hold down its transmit key. Tell the helper not to speak into the microphone.

Then, while the helper holds down the transmit key, walk around inside the marks you made using the steps in "Preparing the Antenna Site" above, covering as much area inside the circle as you can. As you walk, watch the meter's needle. If it moves to the right of 5 on the FIELD STRENGTH scale, rotate the knob on the front of the meter until the needle lines up with 5 on the scale.

Notes: If you use a CB that has sideband modes (SSB), do not select any of these modes. (Use only AM for field strength measurements).

If you have an amateur radio, select the continuous wave (CW) or tuning mode to check the field strength.

4. To measure field strength, as the helper continues to hold down the transmit key, move to the marked spot on the circle due north of the antenna, then watch the meter's needle.

Note the reading on the FIELD STRENGTH scale and place a dot on the template corresponding to the reading at that point.

5. Move to each marked spot along the circular path then repeat Step 4 for each one, taking another reading and recording that reading on the template.

You can use field strength measurements to monitor the effectiveness of changes you make to your radio and antenna while you make them. Changes you might make include:

Installing a new antenna or antenna cable

Adjusting the length of an antenna

Changing the antenna mount on your vehicle

Adjusting your radio's transmitter

IMPORTANT: Be sure to follow any radio service regulations that limit the amount of time you can transmit without a break or station identification.

1. Use supplied antenna for the meter.

2. Set CALIBRATION/FS/SWR to CALIBRATION/FS.

3. To calibrate the meter, have your helper select a channel or frequency on your transmitter and hold down its transmit key. Tell the helper not to speak into the microphone.

Then, while the helper holds down the transmit key, walk around and adjust the meter's knob until the meter's needle moves to 3 on the FIELD STRENGTH scale.

Notes: If you use a CB that has sideband modes (SSB), do not select any of these modes. (Use only AM for field strength measurements).

If you have the amateur ratio, select the continuous wave (CW) or tuning mode to check the field strength.

4. Have the helper release the transmit key, then make a change to your radio or antenna (such as adjusting the antenna or transmitter or adding a new antenna).

5. When the change is completed, have the helper hold down the transmit key again while you watch the meter's needle.

If the field strength reading is higher, you have probably improved the power output and efficiency of your radio and antenna. If the field strength reading is lower, repeat Steps 4 and 5.

Note: If you move the physical location, or change the transmission direction, of your antenna, you might have to recalibrate the meter and measure the field strength again.