Noob needs help getting radios up and running

[watglen]

Hello All,

New to this. I installed 4 -
Uniden PRO520XL 40-Channel CB Radio with
K40 K-30 35-Inch 300 Watts Stainless Steel Magnet Mount CB Antenna
In several mobile machines.
I have limited reception in a couple machines, no reception in one.
When the machines are parked close together, you can carry on a conversation, but when the machines are 1000 feet apart or more, reception is gone entirely.

Can anyone explain this?
As far as the install goes, all I did was unbox everything, build mounts, and mount the radio. Antenna is magnetic. Everything is wired out of the box so all there is to do is hook up power, screw in the mic and antenna. Too simple to screw up.
I did not tune the antenna, whatever that means.

Thanks for your help in advance.

Ken

 

[KB4MSZ]

Wow, there are a lot of variables possible here. What machines are you referring to? Maybe with this situation it would be best to take some photos of the various aspects of the setups, especially with respect to the antennas and how/where they are installed. While tuning the antennas is important, no portion of the antenna element can be in contact with any metal surfaces on these "machines". A short video would be even better.

Until you acquire a bit more information on this it would be a good idea to NOT TRANSMIT until you have some input from others on your setup. Transmitting into an improper antenna load can destroy the output circuit of a radio.

 

[WA0CBW]

What make and model CB antenna did you get? Did you have to put a connector on the cable? Did you pinch or crush the cable getting it into the vehicle? How did you power the radios? Direct to battery? Cigarette lighter plug?

 

[watglen]

Answer some questions for you, the antenna is the K40 model from amazon, detailed in the OP. Everything was prewired and pre-assembled. It was all plug and play
Power is from direct wire into 12V on the machine.
Specifically, one unit is in a farm tractor, one unit is in a steel tracked machine like a bulldozer
I have a unit in a bulldozer and another in an excavator. So 3 on steel tracks and 1 on tires.

I didnt realize you could damage the units by using them.
As far as antenna location, just on the roof of the cab or someplace similar



One thing I do see is the display light come alive when another cb presses the mic button. May not be any audio, but the lights indicate there is something being sent and received. ???

 

[mmckenna]

Yeah, your post raises a lot of questions that are not answered. Filling in some of the details would -really- help us help you. As it stands, anything would be a total guess.

What sort of "machines" are we talking about?

Where are the antennas mounted on the "machines"?

Where are you getting power for the radios? Exactly how and where is it connected?

What sort of environment are you working in? Is this outdoors, in a factory, flat terrain, canyons, hills????

Pictures are worth a thousand words, but even some better descriptions would help.

 

[jassing]

Do you have squelch turned up or down? Turning the squelch up too much would account for not receiving.
Tuning your antenna will improve transmit, but you'd need a good SWR meter.
Does it happen if the equipment is running as well as off?

 

[mmckenna]

And make sure the RF Gain knob is turned UP all the way (clockwise). That will impact receiver performance.

 

[chief21]

One thing I do see is the display light come alive when another cb presses the mic button. May not be any audio, but the lights indicate there is something being sent and received. ???

Check to see that the PA switch is NOT engaged.

 

[jassing]

and ch 9 switch is off.

 

[RFI-EMI-GUY]

Answer some questions for you, the antenna is the K40 model from amazon, detailed in the OP. Everything was prewired and pre-assembled. It was all plug and play
Power is from direct wire into 12V on the machine.
Specifically, one unit is in a farm tractor, one unit is in a steel tracked machine like a bulldozer
I have a unit in a bulldozer and another in an excavator. So 3 on steel tracks and 1 on tires.

I didnt realize you could damage the units by using them.
As far as antenna location, just on the roof of the cab or someplace similar



One thing I do see is the display light come alive when another cb presses the mic button. May not be any audio, but the lights indicate there is something being sent and received. ???

Assuming these are all negative ground 12V powered machines. Make sure the negative lead for the radio goes to a ground point on the chassis, not the battery .

 

[Retroradio]

What’s the SWR. Its a good plan to check the SWR with an external meter.

 

[watglen]

Here is one installation. The power and ground is tapped into the wiring for the AM/FM radio. I am still playing with the radios to better understand what they are doing. For sure if you are near each other you can talk back and forth loud and clear.

Thanks for all the replies. Just understanding what the dials should be set to helps a lot.

Ken

 

[RFI-EMI-GUY]

Having the coax wrapped around the antenna whip is not a good idea. I also note that you have high tension lines nearby. If you park these vehicles a mile or more from each other with the engines off, do the radios sound fine?

The radios need to be grounded to the sheet metal or frame nearby, not into some music radio ground loom.

 

[kb7gjy]

Also a word for later on. The microphones on these radios are NESTORIUS for getting dust in them and when you talk all that is hear is a unintelligible noise. Also these little CBs don't last very long in a dirty or shaking environment (Maybe a season).

I have had to take care of CBs in some dump trucks (both on road and off road) and road building equipment.

Just a FYI.

 

[mmckenna]

Uh, yeah….

So, as RFI-EMI-GUY said, unwind that coax from the antenna. That isn't doing you any good. If you cannot reterminate the cable with a proper connector and -just- the amount of cable you need, then you should neatly fake it out somewhere away from the antenna.

The antenna will require a ground plane. That means a sheet of conductive metal under them. Sticking the antenna down on the little bracket isn't helping you either.

Power for the radio should ideally come off the battery. Tapping into existing wiring is a good way to introduce noise into your system. If at all possible, run the positive lead to the battery positive post (assuming it's a 12 volt system?) and ground the negative lead to the tractor frame/body.

Fix those things, turn your RF gain up clockwise as far as it will go, adjust your squelch so it's just on the edge and give it a try.

And I agree with the idea about trying this with the engine shut off. Could be lots of RF interference coming from other sources in the tractor.

 

[mmckenna]

Oh, and move the CB antenna away from that other antenna.
Also, might be hard to tell from the photo, but that CB antenna looks a little short. Is that the original length from the factory, or did someone lop the top off it?

 

[watglen]

Oh, and move the CB antenna away from that other antenna.
Also, might be hard to tell from the photo, but that CB antenna looks a little short. Is that the original length from the factory, or did someone lop the top off it?

That is the factory length. The package description is 35"

I will try some of these suggestions and see what happens.

One question, does the channel matter to range? I have all the radios tuned to Channel 1.

 

[mmckenna]

That is the factory length. The package description is 35"

OK, that's fine, just making sure. 35" is kind of short for an efficient antenna on CB, but you should still be getting better performance than what you are seeing.

One question, does the channel matter to range? I have all the radios tuned to Channel 1.

No, not if the antenna is tuned correctly. You may find more noise on some channels, avoiding those would help, but still, I don't think that's your issue.

 

[FiveFilter]

Get a $25 SWR meter and check that important antenna factor. I had to cut a little shorter my 35-inch K30 antenna placed on the roof of a car in order to tune it to that car. The SWR should be at 1.5 or lower for best performance. The SWR can change some on each machine the antenna is placed on. As said, place the antenna on as much sheet metal as you can find in order to provide the best ground plane possible on each machine. You should be able to get maybe three miles or so from that antenna. A taller antenna, such as a 62-inch K40 or Wilson 1000, can improve on that.