First Class Radio, Inc. - F.A.Q.'s

What is SWR

Standing Wave Ratio.  The SWR is the ratio of power being output from transmitter to the amount of power being reflected back from the antenna.  With a perfect antenna, there is no power reflected back, and therefore the SWR will always be 1.0:1  For more information, click here

How can I check the SWR.

To read the SWR, first you must calibrate the meter you are using. This should be done each time a reading is taken.  To calibrate the meter, set swr meter (or switch on radio) to "CAL" (or "FWD" on some models).  Key microphone, and adjust calibration knob so that needle goes rightmost to the "CAL" or "SET" indicator.  

Now that the meter is calibrated, you can read the SWR.  To take an SWR reading, set swr meter (or switch on radio) to "SWR". Key microphone, and note the reading on the meter.  This is your SWR. You CANNOT adjust the SWR from the radio/meter.  If your meter shows the SWR to be higher than desireable, adjustments must be made to the antenna system.

Generally, an SWR of less than 2.0:1 is acceptable.  1.0:1 is considered perfect, while an SWR higher than 2.5:1 is considered dangerous to the transmitter, and should be corrected before attempting to transmit on the antenna.

How can I set the SWR

In order to work properly, an antenna needs to be resonant on the frequency [band] you are operating.  Frequency and wavelength are directly in-proportional, meaning that as frequency increases, wavelength decreases.  This information can be used to easily and accurately tune your antenna.

For CB use, If the SWR is lower on channel 1 than it is on 40, make the antenna shorter.  Channel 40 is higher in frequency than channel one, so it's wavelength is shorter, thus requiring a shorter antenna.  Likewise, if the SWR is higher on channel 1 than it is on 40, make the antenna longer.  Only adjust in small increments, like 1/4 inch at a time.  Sometimes it is necessary to trim a bit off the whip. In this case, a bolt-cutter works well, just remember to wear safety glasses and take care, the small pieces can fly off with a lot of force. Cut from the bottom, in 1/4 inch increments.

How to figure coax lengths.

There is much confusion concerning the proper length of coax to use with your cb / ham setup.  In a perfect world, the length of coax does not matter, and should only be as long as needed. If your antenna is a pure 50 ohms, this rule holds true. However, this is rarely the case, and the general rule of thumb is to cut coax lengths to be 1/2 wavelength, or a multiple thereof.   For a typical CB installation, 1/2 wavelength is about 18 feet in free space.  However, the signal travels through coax at a different speed than in free space, and this speed differs depending on the coax.  The difference in speed at which the signal travels through the coax is referred to as the velocity factor, and can be found in the specifications for that type of cable.  For the velocity factor of other cables, click here.

For standard RG8, the velocity factor is 66%.  To determine the length of RG8 coax you should use, take the desired length (1/2 wavelength in this case) multiplied by the velocity factor:  18 x .66 = 12.  This means the actual length of coax you should use would be 12' of RG8.  

My radio isn't working.  What can I do?

Of course, there are too many possible problems to address in a simple FAQ.  The guide below is only intended to help you diagnose and correct the simplest problems.

First, ensure that the radio has power and is turned on.  Check fuse(s) if unit will not power up.
Turn "Volume" up to a comfortable level.
Turn "Squelch"  all the way to the left.
Turn "RF Gain"  All the way to the right
Turn "Mic Gain" or "Dynamike" All the way to the right.
Set "Delta Tune" or "Clarifier" to the 12 o'clock position.
Set "CB/PA" switch to CB.
Set "NB/ANL" to OFF if possible.
Set "S/RF-SWR-CAL" to S/RF

These settings might not be optimal, but should enable you to transmit and receive.  The meter on the front of the radio should move with incoming signals, or when you key the microphone.  If your radio still is not working,  you may try another microphone, as well as an external speaker.  Also, check and set (if possible) the antenna's SWR.  If the problem still exists, the unit most likely needs professional attention.