TK-780 Reception/Squelch Issues

[WelderGuy24]

Currently installing two-ways in our fleet of Excavators/Dozers/Pickups/Semi's, I have roughly 15 units to install and am about a third of the way through this process. We are an excavating company with our own channel (159.xxx) that contracts for a class 1 railroad using their channels when on site (AAR 160.xxx). We have about 8 NX-210 portables, and now this winter I'm installing roughly 15 mobiles in our equipment, 1 TK-760HG, 5 TK-780H, 10 TK-780, and 2 TK-7180H (all purchased used). I'm also installing NMO mounts in the center of the roofs (PCTEL-NMO58U) and using 1/4 wave (PCTCN1520) and 5/8 wave (Larson NMO150C) antennas.

So here's the issue I'm having. 2 of the 4 excavators (CAT 329E's and F's) I've installed 780's in, and 1 dozer (CAT D6K) have constant static. On our own channel we run 127.3 PL tone, the squelch stays closed but green receive led stays on, then on the AAR channels that use no tone it's just constant static. I've tried swapping radios, antennas, checked SWR, nothing changes. On the NX-210's in the software I can adjust squelch level, as well as the TK-7180's. I just swapped a 7180 in this dozer and had no issues, set squelch level down to 1 and worked great. I've searched all over in the KPG-49D version 4.02 and I can't find any option or setting for squelch level. Am I missing something here?

 

[buddrousa]

If I remember it is under test mode tab and work to it you should find it.

 

[WelderGuy24]

Man this forum rocks, the wealth of help and knowledge here is amazing. So I enabled panel test and panel tuning as well as setting test freqs 1 and 2 to my main two channels used, went into panel tuning mode on radio, set to my test channel, cycled through to wide and narrow squelch and set about 20 above when squelch muted (1-256, muted about 180, set to 200) and saved.

Now, is there any rhyme or reason to any of these values? What about any of the other options? And do I have to do this for every radio individually? Or can I now read this radio with KPG-49D and then send to others and these settings will follow?

Again, thanks so much for the help.

EDIT: Attached page from service manual with map of tuning mode, but cant find anything in the manual about the values or definitions of the other options.

 

[mmckenna]

Now, is there any rhyme or reason to any of these values?

Sort of/not really.
There are a lot of variables involved. The noise may be coming directly from the machine, and that's going to vary. Some vehicles have higher RF noise levels than others. It will also vary depending on the alignment of the radio.

What about any of the other options?

I caution against making any changes to the radios via the front panel mode. Without the proper test equipment it is -very- easy to screw things up with the radio. That can cause the radio to not work correctly, or cause interference to other users on other frequencies.

And do I have to do this for every radio individually?

You may need to.

Or can I now read this radio with KPG-49D and then send to others and these settings will follow?

The information in the "Panel Tuning" mode is part of the test mode. That information is specific to each radio alignment and is not carried over via programming software. Each radio is going to have different alignment values based on component tolerances. You absolutely do not want to copy that information over from radio to radio. The software won't do that, luckily.

EDIT: Attached page from service manual with map of tuning mode, but cant find anything in the manual about the values or definitions of the other options.

Right. It's alignment info and that varies from radio to radio. There is no one setting that applies to every radio. To do this level work, you need a couple of costly pieces of test equipment and the knowledge to use them. If you believe the radios are not working correctly, or if the are older radios, it's always a wise idea to have a competent radio shop (not some amateur radio operator) put each radio on their bench and realign them to factory specs. The FCC license your company holds requires the radios to work within specific parameters. The only way to make sure of that is to use a service monitor. A new service monitor will run you about $40,000. It's really worth paying a competent radio shop to do this for you. Usually bench time runs in the $85-$100/hour. A good tech can align a radio in an hour or less.

 

[wwhitby]

FWIW, I used to have a TK-780 in my car, and I found it had a very hot receiver. I liked the sensitive receiver, but It would break squelch like you have experienced in drive throughs, toll booths, passing digital billboards, near vehicles using cheap strobe lights, some nearby vehicle's ignition systems and other RF emitters. Even some electronics operated close to the radio would break squelch, so I always suspected it was coming in through the radio and not the antenna. Since I don't have access to test equipment, I wasn't able to check its tuning to see if the sensitivity was set too high.

I replaced it with a 7180 and haven't had that problem. Unlike the 7180, the 780's squelch Level is set in the test mode, but I wouldn't mess with that unless you have test equipment. And, as mmckenna correctly said, its not the same from radio to radio.

For me, I had learned to live it with and shut the radio off temporarily until I passed by the emitter, or ignore it for a few seconds. But in your situation, it would be impossible to do. Most likely, its the electronics of the heavy equipment that are causing the problem. I also suspect that the interference is coming in through the radio, and not the antenna. I'm not a heavy equipment guy, but can you check the grounding on the excavators and the dozer? Can you also speak to your Caterpillar service rep about the problem? You could try a ground wire from the radio's body to a verified ground, but that may not work. I hate to say it, but you may have to end up replacing the 780s in the excavators and dozer with another model like the 7180 or a newer series.

 

[DeoVindice]

FWIW, I used to have a TK-780 in my car, and I found it had a very hot receiver. I liked the sensitive receiver, but It would break squelch like you have experienced in drive throughs, toll booths, passing digital billboards, near vehicles using cheap strobe lights, some nearby vehicle's ignition systems and other RF emitters. Even some electronics operated close to the radio would break squelch, so I always suspected it was coming in through the radio and not the antenna. Since I don't have access to test equipment, I wasn't able to check its tuning to see if the sensitivity was set too high.

I replaced it with a 7180 and haven't had that problem. Unlike the 7180, the 780's squelch Level is set in the test mode, but I wouldn't mess with that unless you have test equipment. And, as mmckenna correctly said, its not the same from radio to radio.

For me, I had learned to live it with and shut the radio off temporarily until I passed by the emitter, or ignore it for a few seconds. But in your situation, it would be impossible to do. Most likely, its the electronics of the heavy equipment that are causing the problem. I also suspect that the interference is coming in through the radio, and not the antenna. I'm not a heavy equipment guy, but can you check the grounding on the excavators and the dozer? Can you also speak to your Caterpillar service rep about the problem? You could try a ground wire from the radio's body to a verified ground, but that may not work. I hate to say it, but you may have to end up replacing the 780s in the excavators and dozer with another model like the 7180 or a newer series.

For what it's worth, one mine I worked at ran NX-900s (why would an operation in rough terrain use a single-site 800 MHz conventional system? I don't know either) in a variety of CAT heavy equipment built about 1990-present with no issues. There were a bunch of TK-980s in storage but only a handful on service.