XTL Missing Some Encrypted Messages. Why?

[kb1fys]

XTL radios missing some encrypted messages. What settings am I missing?

I have several XTL 1500, 2500, 5000 series that are missing some ADP encrypted transmissions, especially worse while scanning. There has to be something I'm missing unless the tuning on these radios are so far off.... The programming is the same as several other XTL series radios that seem to work fine. The keys are correct, the modulation is correct, the NAC codes are right. Is there any other settings that anyone can think of that would cause this? Firmware upgrades that you know of that fixed this issue?

 

[K2NEC]

Conventional or trunking?

 

[kb1fys]

Conventional or trunking?

Conventional

 

[K2NEC]

Though these radios have an acceptable drift that they can go out of alignment, the XTL series are getting up there in age. Do you know when the last time they got any service was?

I'm assuming your signal is strong? If the radio misses the HDU which tells it which key to use, it could also cause a delay in decoding audio.

 

[kb1fys]

Thanks for the input so far. Yes the signal strength is good. I am not sure when the last time they were serviced. I'm leaning towards them being out of alignment to be the main problem here.

 

[n3obl]

I second the alignment as it’s required especially with p25 signals. Further out of alignment causes reception issues.

 

[wa8pyr]

I second the alignment as it’s required especially with p25 signals. Further out of alignment causes reception issues.

Alignment would be the first thing I’d check. If the BER is just a bit too wonky, you’ll have any number of problems, including this one.

 

[MTS2000des]

15-20 year old used radios need alignment at least once a year as components age, values drift. On analog FM, a 75Hz freq error doesn't amount to much degradation, on digital it's a huge performance drop especially if DSP is way outta date.

 

[K2NEC]

15-20 year old used radios need alignment at least once a year as components age, values drift. On analog FM, a 75Hz freq error doesn't amount to much degradation, on digital it's a huge performance drop especially if DSP is way outta date.

At least once a year is a bit much, I have AN 6500s that have been in service for over 10 years and still perform great without seeing a service monitor for 2+ years.

OPs XTLs definitely could use a tune up, but after that they should be good for at least the next few years. Unless XTL components are wildly different than APX in which case I will put my foot in my mouth...

 

[prcguy]

You can usually do a basic alignment with a service monitor and Astro service software. Set the radio right on frequency then check, align the P25 tx test waveform looking at the demod waveform on an oscilloscope.

 

[MTS2000des]

At least once a year is a bit much, I have AN 6500s that have been in service for over 10 years and still perform great without seeing a service monitor for 2+ years.

Yearly PMs are not a bad thing, one must also consider the environment a radio is installed in. A control station sitting on a desk can fare better than a mobile installed in the trunk of a hot car being bounced around.
FWIW I have two DiagnostX boxes on my system and find 6500BNs made in 2021 off frequency by 400Hz. If an SU that is two decades old is having problems and it's never seen a service monitor, that's a good start...

 

[N4DES]

XTL radios missing some encrypted messages. What settings am I missing?

I have several XTL 1500, 2500, 5000 series that are missing some ADP encrypted transmissions, especially worse while scanning. There has to be something I'm missing unless the tuning on these radios are so far off.... The programming is the same as several other XTL series radios that seem to work fine. The keys are correct, the modulation is correct, the NAC codes are right. Is there any other settings that anyone can think of that would cause this? Firmware upgrades that you know of that fixed this issue?

Different firmware versions shouldn't cause you drop calls, but if they are all at a similar version the audio quality would be consistent.
MSI made a lot of P25 vocoder improvements in FW versions 12, 14, and again in 19 before stopping all updates in FW20.

Unfortunately updating the FW versions correctly with a Refresh Key is difficult because MSI no longer sells the key.

 

[K2NEC]

Yearly PMs are not a bad thing, one must also consider the environment a radio is installed in. A control station sitting on a desk can fare better than a mobile installed in the trunk of a hot car being bounced around.

Totally agree there, you know as well as I do that getting every radio in for service is a nearly impossible task lol

OP, get the radio serviced and report back if it resolved your issues

 

[mbnv992]

Yearly PMs are not a bad thing, one must also consider the environment a radio is installed in. A control station sitting on a desk can fare better than a mobile installed in the trunk of a hot car being bounced around.
FWIW I have two DiagnostX boxes on my system and find 6500BNs made in 2021 off frequency by 400Hz. If an SU that is two decades old is having problems and it's never seen a service monitor, that's a good start...

This right here.

Amazingly, I have two 110Watt Astro Spectra’s ( one UHF one VHF ) mounted in the trunk of my 2014 Taurus ( in AZ no less - where it gets 120*F outside ) that’s still going strong. Its last tune and alignment was YEARS ago. Granted - these are just “hobby” radios and I would never do this with Public Safety radios in active use. But - it’s a Christmas Miracle that these things are still going. None have ever had a capacitor issue / replacement done either.