jadmt

So there were three of us that tuned are antennas to well under 2 on 1 and 40 and we had great reception when we were 1 mile to say 300 yards from each other but when we got closer then say 300 yards we had issues copying each other. what would cause this. It made running on the trail tough.

psouza

It is difficult to design an AM receiver, at low price, that will have an AGC (automatic gain control) with enough dynamic range to operate under the conditions you describe. Some manufacturers will compensate for this shortcoming by adding a RF gain control that allows the operator to manually reduce the receiver gain at close range. Lower the RF gain, if you have the control for it, when close to others.

You are experiencing a normal but unfortunate byproduct of lower tier CB radio design. Spending more money on a radio is not a sure cure but your chances are better with a better radio. There is nothing you can change in your installation except (unlikely) trying a shorter antenna (lots shorter) for close in communication. Simply too much transmit power for your receivers. Ironic, after all the work to make the best antenna installation possible.

Late edit: You might try talking softer to one another (seriously). This will not lower the carrier power, but it will reduce the side band energy (where the audio information is) . This might help close in. Lower microphone gain if you're so equipped.

Phil

jadmt

thanks for the get back. we do have the cheapy cobra ultra 19 radio ($34) so no adjustments. would a better mic help? there were times when it would have been nice for spotting someone down a difficult obstacle from either behind or below but those were too close. thanks for your taking time to help.

psouza

If the signals all sound good from a distance, then the microphones are not a problem. The easiest and cheapest solution, for spotting, might be hand helds. That would solve the high distortion audio problem but add the trouble and complexity of "other things to worry about".

Finding a way to reduce receiver sensitivity or transmitter power output (or both) via a smaller, less efficient antenna is more practical than buying newer, better, radios. Buying different radios will not be a sure thing for you, since there is no way to tell before hand if the one you buy is any better than what you have.

I want to repeat...really give talking at a lower voice level a try and see if things improve. It's free!

I have seen, and experienced this problem first hand many times and as an ex pro radio tech....I learned to adapt and live with it.

Eye to eye contact and hand signals while spotting is the best way, in my opinion, especially for really technical sections any way. Warnings and advisories at a distance for things less difficult should be sufficient, depending on skill levels of those behind you. In other words, changing trail procedures may be easier than changing radios.

I don't see a better, cheap way.

Phil

KG6SLC

Let's look at an example, with which most of us are familiar, to help us understand what is happening here:

When using a PA(Public Address) amplifier if you hold the mike away from your face you can yell and the sound coming through the speakers will be accurately reproduced and can be understood. If you then hold the mike directly in front of your mouth and yell at the same level, the intensity of the sound going into the microphone directly in front of your mouth will cause the amplifier to be over driven and you will hear garbled sound.

In this example your voice can be compared to the CB transmitter (which always puts out the same power) and the mike, that receives your voice, can be compared to the CB receiver. At close range the strong signal is too much for the "front end" of the radio to accurately process and the result will be distorted/unintelligible sound.

In this example we are using audio to illustrate. The CB radio signal is RF or Radio Frequency. However the physics are similar. In fact, you can google antenna spacing for more information.

KG6SLC aka eugene

Mark Doiron

I've never experienced or heard of this with those I run with. Most of us use the Cobra 75 WXST. It certainly could be a reason to avoid certain radio models.

psouza

Very good functional example.

I use a WX75 and while I would not qualify it as a great radio, I have never had the front end overload on the trail.

Phil