Troubleshooting Uplink

[SkiPatrolRadio]

Greetings everyone. I am one of the people responsible for communications for our local volunteer first response agencies. We pay for a dispatch service which provides us with repeater service and site maintenance. Over the last few years, the quality of our transmissions from all of our field radios (the lower power portables especially) has degraded across all agencies. Our dispatch provides points the finger back at us saying it is our radios - that we need to replace batteries and that all the tests they do are fine. It is not perfect from the mobiles either but better given their higher power output. I want to approach this methodically and gather the appropriate data to get to the root of the issues. I am buying a simple tester to test the output of our portables. However, anything else anyone things would be good to gather the appropriate data.

It's a very simple analog VHF system in the 154 mhx range. We do operate in a fairly mountainous area so terrain and line of site are issues but, as I said, it did work fine and has degraded over time. I maintain there is an issue with the Rx antenna, cabling, etc but dispatch maintains they've tested it and it's fine. I really don't care where the issue lies I just want to find it and remedy it. Thanks.

I also have a USB SDR if anyone has any suggestions on test / monitoring programs and setups. Thanks.

 

[WA0CBW]

When was the last time you PM'd the radios and how old are the batteries? A VHF watt meter and dummy load would let you test the portable radios power output.
bb

 

[SkiPatrolRadio]

Batteries may be old on some. What other PM would you recommend other than replacing batteries? Thanks.

 

[WA0CBW]

I would check the antennas. Either a return loss measurement or a simple field strength measurement should weed out most of the bad ones. You may need to provide a "refresher" class on correct radio usage. Over time users can get sloppy in how they speak into the microphone or holding the radio other than vertical when transmitting. I once worked a complaint of poor performance where the users were carrying their ring of access keys on the radios antenna. Other than the normal "PM" of frequency, sensitivity, and power that should capture most of any problems.
bb

 

[speedway_navigator]

The repeater site could have had an increase in the noise floor over time which would affect coverage. Ask them if they have done an effective sensitivity test.

Portable antennas take a beating, that's a cheap fix.

Are there other users on your tower? Are they having problems?

Is this weather related or constant? I lose the county east of me on my scanner after a heavy rain or snow like we had this week, the signal comes back after 3 or 4 days. Since my scanner is inside I suspect a minor coax leak on their end.

A mobile antenna NMO mount can collect water over time which affects performance.
One of these adapters comes in handy for checking coax loss from the radio to the antenna.

https://www.theantennafarm.com/catalog/comet-ad-10n-4370

 

[wa8pyr]

The repeater site could have had an increase in the noise floor over time which would affect coverage. Ask them if they have done an effective sensitivity test.

The RX alignment on the repeater could be off; how long has it been since the repeaters and/or base radios got a preventive maintenance check? It should be done on a repeater or base station at least annually; in a proper PM check the tech should put a service monitor on the system and follow the alignment procedures in the service manual. Mobile and portable radios should get a PM check at least every other year (depending on how much they get beat around), and preferably annually.

 

[Project25_MASTR]

Ask the dispatch service for the results of the annual repeater PM. The results should include, frequency error, deviation, power output, loss through the duplexer, desense, site noise and if possible, a sweep of the antenna and feedline. If they are unable to provide it, they have zero footing to tell you the problem is your equipment (having someone come in and perform a basic function check on your equipment would be good supporting evidence).

 

[ladn]

In addition to the physical equipment checks others have mentioned, it would be beneficial to look at other users at (or near) your radio site and in your operational area. Are there any new users or frequency changes? Or have any users at (or near) your radio site made hardware changes such as a new antenna?

 

[speedway_navigator]

having someone come in and perform a basic function check on your equipment would be good supporting evidence

I've wondered if there was a viable business in auditing radio shop performance. I'm going to bring it up at our next advisory board meeting.
I had complaints about poor paging from an FD and noticed how poorly it sounded on my radio. The service shop said nothing was wrong but when paging went out during a CAD cut over they found an external PA had gone bad.
Even though no one complained after the PA was removed and the existing xmtr was feeding the antenna the county went ahead and bought an new PA.

 

[TampaTyron]

Speedway,
I have often asked that question myself. In working with many, many shops over the last several years (about 3-4 different ones a month), I have found that most believe they are the best in the area and that all other local shops are terrible. Additionally, they are not interested in learning new things or investing in new equipment. My take on this is that they likely would not pay for someone to tell them where they are lacking...... TT

 

[speedway_navigator]

I guess the marketing thrust would be an auditing service to the end user along the lines of Regan's 'trust but verify' thinking.

 

[TampaTyron]

Similar to "......Xxx brand radio customer, wondering if your local radio shop is doing all they can for you....?" Or "....Xxx brand radio customer, wondering how much better your radio system could be....?"
TT

 

[Project25_MASTR]

Ever since I worked for a large shop I've been thinking a auditor (check the quality of the jobs, etc) would be a great thing. Especially since the norm has become, grab some LMR400, a cheap mobile duplexer and repeater, throw it up and call it good mentality of most of your RCA, Bearcom, Crosspointe type shops with the techs only truly trying to diagnose issues if "it's not making power".