SWR shows the efficiency of the CB antenna in giving away the power generated by the radio to the atmosphere.
Achieving Low SWR holds great importance in CB system. If you are thinking…
HOW YOU WILL ACHIEVE THE LOW SWR READING?
Don’t Worry! After reading this guide completely you will be able to get low reading, it doesn’t matter which antenna you are using.
Let’s begin! These 15 minutes will validate your high SWR results. But before all this you need to have
- Appropriately installed antenna system (mount, coax and antenna) that is compatible with the type of radio you own and there should be no shorts or other defects in the system.
- A perfectly working CB radio.
- SWR meter (internal or external)
- A defined length of jumper coaxial cable having PL-259 connectors at both extremes.
Maximum Time 4 minutes
First remove the coaxial cable from its jack on the CB radio. Connect it to the SWR connector that is labeled as “Antenna” or “Ant”. Now, connect the jumper cable to the rear side of the CB radio on one end and to the SWR meter connector labeled as “Transmitter” or “Xmit” on the other end.
Maximum Time 2 minutes
Once everything is in place and you are in an open area with your car’s doors locked, tune your radio into the lowest channel that your radio broadcasts. Don’t forget to bring the radio to the AM mode before beginning the tests.
Maximum Time 3 minutes
Now that you are tuned into the channel 1 on CB radio, bring the SWR meter’s switch in the Forward (FWD) position and key up the switch on the microphone. This will keep it in the transmit mode. Sustain this mode; use the Set or Adjust knob to bring the needle to the set position. Once the needle reaches that point, turn the switch to Reference (REF) position. This will give you your SWR measurement for channel 1.
Maximum Time 3 minutes
Next tune into channel 19. Turn the switch to the Forward (FWD) position, key up the microphone switch and repeat the above mentioned process to make the needle reach the set position. Finally bring the switch to Reference (REF) position and take the reading. Complete the remaining steps and you have your SWR measurement for channel 19. If your radio and antenna are highly compatible, meter needle will show very limited or no movement and that is a good sign.
Maximum Time 3 minutes
Now tune into the last channel of the CB channel 40. Repeat the same process described above to get the needle to the set position. After that, move the switch to the point marked ‘Reference (REF)’ and mark the reading. Unkey the microphone switch and note the SWR reading for the channel 40.
Now you are ready to get ON AIR on your CB system.
What readings speaks to you
1.0 to 1.5
|Antenna length & Cable match up CB radio need totally.|
1.6 to 1.9
|Needs improvements but still adequate mostly it is due to vehicles variables.|
2.0 to 2.9
|It cause can damage your CB Radio, mostly due to selecting wrong CB antenna mounting location.|
|Extreme harmful for your radio in this range. It can be due to incorrect assembled stud, poor ground, faulty coax and antenna or SWR meter.|
How you can achieve Low SWR reading
- Confirm that you have mounted your CB Antenna according to the manufacturer’s instructions (User Manual).
- Be sure that your cable is not damaged & you are using the type of cable recommended for your equipment.
- Connection of wires should be strong with SWR meter & Radio.
- You can achieve best results by adjusting antenna length slightly.
Long Antenna Adjustment
In case, SWR meter show on all channels is 3.0 or above, there are some serious issues with your coax in the form of shorts or opens, or you have not mounted your antenna correctly. Never try to operate your radio with such a high SWR.
If the SWR on channel 40 is of higher value than that on the lowest channel, the length of your antenna is longer than the standard and it needs to be shortened. If your antenna has a tunable tip, you can simply screw it down to decrease antenna length. Otherwise you can manually shorten it by trimming off the wire by small bits up to a specific limit.
Short Antenna Adjustment
When the SWR on the lowest channel is higher in value than that on the highest channel, the length of your antenna is shorter than the standard size. It needs to be readjusted.
When the SWR meter reading on the channel 1 is higher in value than that on the channel 40, the length of your antenna is shorter than the standard size. It needs to be readjusted. Such readings often are obtained when the antenna system does not have enough ground planes to stand on. Here slight increase in length can help. It is done by adding antenna spring between the whip and the mount. Quick disconnect also helps in quite the same way. If dual (co-phased) antennas or special no-ground-plane antennas are installed, they can also remove this deficiency but that is used in rare cases.
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