SWR readings

"If SWR on channels 1, 19 & 40 is below 2.0 your radio can be operated safely" What does operated safely consist of?


Anyway I slapped on a shorter antenna (2ft not tunable) and im getting great readings on ch. 1 & 19 (1.4), however ch.40 is greater (2.9) than channel 1 indicating my antenna is to "long". what do i do to go about reducing the conductor length or should i just say eff it and leave it?

safely means without blowing the transistors in your cb. You are trying to send out a signal without much voltage being reflected back. If you are reading a 2.9 on channel 40 try a different antenna or location. my range is from a 1.2-1.5 from 1-40 with a 3 ft magnamount on my roof.

from what i have read, my higher reading on ch.40 means my antenna is too long, but i only have a 2ft antenna. cant get much shorter than that right?

If i remember correctly, isnt there a way to trim the antenna? since it is not tunable.

If your ant is a fiberglass stick wound with copper wire, you can take off the cap, pull up a small amount of wire ( 1 - 2 turns ), and clip off 1/8 to 1/4 inch. Check your new result and repeat if need. WARNING start slow and be conservative, if you cut too much off you are scr*w*d . Go to www.firestik.com and check out the FAQ and tech sections. Short antennas are less able to have low swr at both 1 and 40 than longer ones. Anything less than 2.0 to 1 will be ok.

crookedxj said:

"If SWR on channels 1, 19 & 40 is below 2.0 your radio can be operated safely" What does operated safely consist of?


Anyway I slapped on a shorter antenna (2ft not tunable) and im getting great readings on ch. 1 & 19 (1.4), however ch.40 is greater (2.9) than channel 1 indicating my antenna is to "long". what do i do to go about reducing the conductor length or should i just say eff it and leave it?

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First, 'safely' means, anytime you want with no damage to your radio. A high SWR means you have a good deal of your power being reflected back down the coax, and into the radio.


First step in reducing your SWR is making sure you have the antenna, and the radio chassis grounded well. You don't say what kind of mount the antenna uses, but running a ground wire to a frame ground, then running one from the radio chassis to the frame may bring down the SWR.

Now 2.9 on 40 isn't a problem if you are only using up to channel 20. Remember if you are running illegal power, your readings may not be accurate anyway. Most methods of turning up a CB's power open up or remove filtering stages, and cause a very wide(frequency wise) signal. Some of this sloppy signal will reflect back causing a higher reading.

w_howey said:

Now 2.9 on 40 isn't a problem if you are only using up to channel 20.

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Cool I thought this was correct but just wanted to make sure. I dont use it over ch.20.
Thanks for the replies.

while were on this subject, where are you guys runnin your cable into the cab from a magnet mount? i need to buy a antenna for my new c.b.

I ran mine through a big rubber grommet that is next to the left taillight. It doesn't have a hole, but you can put one in then silicone it back up and pop the grommet back in.

A friend of mine drilled through his roof to mount his antenna. It never leaked but the noise from it banging on trees would drive you CRAZY!

HarveOut-

crookedxj said:

...
Anyway I slapped on a shorter antenna (2ft not tunable) and im getting great readings on ch. 1 & 19 (1.4), however ch.40 is greater (2.9) than channel 1 indicating my antenna is to "long". what do i do to go about reducing the conductor length or should i just say eff it and leave it?

Click to expand...

As measured with what?

1.4 what?, what is the Rx?

Just wondering what people are using...

MFJ-269 or stop wasting time, just use it how it is.

--ron