Car Radio Repair: Adjusting the Antenna Car Radio Repair: Adjusting the Antenna

What You'll Need
SWR Meter

One of the most important jobs in car radio repair is adjusting the antenna to work just right. Correct adjustment will ensure that the correct frequencies can be caught and sent to the radio for clear output through the speakers. The key lies in setting the Standing Wave Ratio (SWR) right for lower and higher channels on the radio. It seems like a complicated process, but with the right instructions, the job can be easily done. Follow this guide to learn how to adjust the antenna when doing a car radio repair. This guide will also teach you how to understand specific SWR readings and different antenna mechanisms. The tools and materials needed for the job are given below. 

Step 1 – Mount the Antenna

The first step is to connect the antenna to the radio. Mount the antenna and connect its coaxial cable to the radio. Do this by running it through the SWR meter. That is, first connect the coaxial cable into the front input of the SWR meter and then use a patch cable from the back of the meter and connect it into the radio. 

Step 2 – Pick a Channel to Check 

The trick is to first pick a channel that has a low radio frequency. For a low frequency channel, 1 or 2 for example, check the SWR meter reading. The reading on the meter for this low channel should be below 1.5. If it is below 1.5, you don’t need to adjust anything now. Then, change to a channel with a higher frequency and observe the reading on the meter. It should still be below 1.5 for the antenna to be adjusted and functioning well. If the reading on the meter is higher than 1.5, move to the next step. 

Step 3 - Adjust the Antenna 

This is the most important part of this type of car radio repair. Adjust the antenna’s length to be either shorter or longer than its current length. If the SWR reading you got on the low frequency channel was higher than 1.5, make the antenna’s length longer. If the reading was high on the high frequency channel, make the antenna’s length shorter. That’s the rule. Keep doing that until the reading on the meter is right. 

Step 4 – Learning How to Adjust the Antenna Well 

Some antennas come with locking rings. It is best to unwind the rings first. You should loosen the locking rings one by one and move the antenna up. If the antenna comes with a setscrew mechanism, just loosen the setscrew and raise the antenna as much as you want. Once you get the desired length, tighten the setscrew.  

Step 5 – Finishing the Job 

After you’ve done all the adjustments, check the reading on the SWR meter again. Keep repeating the process until the correct reading is reached for both lower and higher frequency channels.

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