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Old 08-31-2016, 12:30 AM
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Question Motorola XTL 2500 receiving issue

Hello All,

I have never posted on this site. I am a full time patrol deputy and a part time emergency equipment installer. I do not have a lot of knowledge when it comes to the digital systems or how they work. I know about enough to get me in trouble. So here is my problemÖ

INFO: Installed in my current patrol vehicle a 2015 Ford PI Utility SUV, I have a Motorola XTL 2500 (Digital 800), Motorola PM400 (UHF) & Motorola PM400 (VHF). My XTL 2500 is having issues reaching the towers when others in my department or the Highway Patrol donít have this problem. Let me explain. Our radios normally jump from about four different towers depending on where we are in the county. The county in which I work specifically doesnít have a tower in it. We are on the Kansas State system and monitor KHP traffic along with surrounding counties on the state system. My vehicle is a slick top and have all three antennas mounted in the center of the roof in a straight line. Each antenna is right at or just over 1ft apart (I know not 18 inches). The XTL 2500 has a Laird Tech. #ETRAB8063 806-866MHz 3dBMEG Phantom Elite NMO Style antenna, PM400 (UHF) has a Laird Tech. #ETRAB4503 450-470MHz 3dBMEG Phantom Elite NMO Style antenna and the PM400 (VHF) has a Laird Tech. quarter wave antenna. They are mounted on the roof in that order with the 800 MHz antenna being closest to the front of the vehicle. There is no light bar mounted to the exterior of the vehicle either.

ISSUE: I can be parked right next to another deputy or trooper running the same radio and same scan list. We will both be hitting the same tower for the example we will just say Tower ďAĒ. When someone starts transmitting on letís say Channel 1, they will pick them up and I wonít. I can even be parked closer to the tower and they will still get them and my radio will be silent. My vehicle is even taller than the chargers and they still hit the tower better. After pressing the RSSI button Iíll be hitting the tower at like 67 and my follow deputy will be hitting the tower at like 96. Sometimes I will be 20 miles from the tower and be in the 60ís then I get 40 miles from the tower an Iím in the 80ís. When I get within 10 miles Iím normally or 100. However same thing will happen while Iím driving down the road and I have my XTS5000 handheld on. My handheld will pick up transmissions my mobile wonít and they are hitting the same tower. My XTS5000 sometimes even has a lower RSSI reading and picks up channel 1, when my mobile never does. Now many may ask are you sure you have your scan bank set up correctly. The answer is yes. I am very familiar with setting up the scan lists, as I set the rest of our radios up for the other deputies whose radios are receiving better. Yes, my scan is on. Do I have good power? The answer is yes. It is connected to the battery as the manual says. Is the coax cable bad? No it was just checked by the Motorola tech, using some device Iíve never seen. They said no reflectivity problem. The coax cables do all meet near the F pillar and run together on their way to the console, I donít know if thatís an issue or not. Now the other thing to note is the other deputies all run different antennas. Some run the longer antennas with the coils in them, others run small quarter wave ones, but they all seem to work better than my Phantom antenna, but I canít understand why? Its 3d MEG? The radio was just ran through all the test at the local Motorola radio shop and passed everything. It took it 3x times they said and was way would off frequency. Even them fixing all the errors it still didnít fix my problem. So I am at a loss. The only other thing I can think of is I know when time the screw in part of the coax cable made contact with a positive. It bounced of the positive contact. It did make a pop sound, however didnít even blow the fuse. The current antenna I have now was installed at that time. Should I try a different antenna? If so which one?

Any advice, or tips would be greatly appreciated. Thanks in advance.
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Old 08-31-2016, 7:41 AM
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Its your antenna. Those low profile phantom antennas are not as good as the normal antenna. Replace it and you'll notice an immediate difference.
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Old 08-31-2016, 7:51 AM
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I agree, get rid of the Phantom antenna and go to the one with the coil in the middle.
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Old 08-31-2016, 7:55 AM
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Should I also change my UHF Phantom?
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Old 08-31-2016, 8:01 AM
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Quote:
Originally Posted by KS4VT View Post
I agree, get rid of the Phantom antenna and go to the one with the coil in the middle.
Unless I missed it, I don't believe that you made any comment on what the other vehicles were using for an antenna. As has been stated the Phantom antennas are not the best choice unless your right near the towers. Being out in the boonies and near the limit of coverage, you need the best antenna that can be put on your vehicle. Have the radio shop put a normal 800 antenna on your vehicle.

Unless you go into a low parking garage on a normal daily basis, there is no functional reason for the use of those Phantom antennas. They are made to be low profile and for close in to the tower use. Bottom line they are not much better than a wet piece of string as an antenna.
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Old 08-31-2016, 8:08 AM
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Quote:
Originally Posted by kparr_90 View Post
The only other thing I can think of is I know when time the screw in part of the coax cable made contact with a positive. It bounced of the positive contact. It did make a pop sound, however didnít even blow the fuse. The current antenna I have now was installed at that time. Should I try a different antenna? If so which one?

Any advice, or tips would be greatly appreciated. Thanks in advance.
Not sure about the designs on these phantom antennas, but running 12 volts through the center may have been the issue. Since the base is grounded and some antenna designs are "DC grounded", you could have run enough current through it to melt the traces off the little circuit board thats inside the phantom antenna.

These phantom antennas are generally really poor performers, but on 800MHz they are not quite as bad as they are on the lower frequencies. I agree with the others, probably your antenna. It's easy to test/fix.

What you can do it borrow the 800MHz antenna off one of the other cars that you know receives well. Swap it with your antenna and see if the issue resolves.

If it does, a 1/4 800MHz antenna is less than $10.00. The 3dB gain whips are not much more.
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Old 08-31-2016, 12:35 PM
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Can anyone recommend the correct Larid Tech antenna I should try? I prefer a black antenna. Also think I'm gonna pitch the Phantom UHF now so if someone could recommend one for that also. Thanks for the quick responses
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Old 08-31-2016, 5:27 PM
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Here's a start.
NMO mount black 800MHz antennas:
I use the 1/4 wave almost exclusively at work on about 50 mobile installs:
http://www.theantennafarm.com/catalo...c800b-881.html

For a gain antenna on 800:
http://www.theantennafarm.com/catalo...8253-3280.html
On our PD cars, I use these:
http://www.theantennafarm.com/catalo...800b-5922.html
Not all black, the whip segments are chrome.

For UHF:
http://www.theantennafarm.com/catalo...wb450-796.html
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Old 09-13-2016, 10:16 PM
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Question Update

Thank you to everyone who has responded, however it seems I'm still having problems. I changed my antennas to as follows.

1) Front antenna: UHF 450 - 470 Laird Technologies QWB450. This is a 6 inch; 1/4 wave antenna

2) Middle antenna: 800 MHz 806-866 Laird Technologies QWB8063. This is a 14 inch; 3dB gain flexible 5/8 over 1/4 wave antenna.

3) Rear antenna: VHF 152 - 162 Laird Technologies QWB152. This is a 18 inch; 1/4 wave antenna.

At first I thought I gained a lot of signal with the new 800 MHz 806-866 Laird Technologies QWB8063. This is a 14 inch; 3dB gain flexible 5/8 over 1/4 wave antenna. However while I was sitting right next to a vehicle that had a phantom mounted to a L bracket coming off the hood, we had the same RSSI reading. I just don't understand how that's possible when I have mine mounted to the roof of my Ford SUV. Anyways the signal in the town of Larned, Kansas (population 4,000) was in the low 60's to 50's. The middle of Larned is on a big hill. However the rest of the county is mostly flat with a few hilly areas. We are in central Kansas so its pretty flat. Remember we do not have any towers in the county. So generally I'm at least 15, 20, 30 to even 40 miles away from the towers. Generally my radio switchs to the closes tower, but sometimes holds on the ther father one.

Questions:

1) Can someone explain what "3dB gain flexible 5/8 over 1/4 wave" is? I somewhat understand the 3dB gain, however I haven't ever seen 5/8 over 1/4 wave. All I have ever seen is either 5/8 or 1/4 wave antennas.

2) Given my terrian and distance from the antennas should I stick with my 3dB gain antenna or should I switch to a 1/4 wave antenna? At one time when I was comparing my radio to my patrners they were using a 1/4 wave on the exact same radio, same Ford SUV, hitting the same tower, both mounted the same. The only difference is they were facing away from the tower and I was facing toward the tower. They were in the 90's and I was in the 60's. We weren't really by any big builds or houses, but near a city park.

3) Why does my radio sometimes hold on to the farther tower when there is a tower closer? And why sometimes does the closer tower have a lower siganl than the father tower?

Thanks for all your expert help again!
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Old 09-14-2016, 8:54 AM
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There is nothing wrong with the phantom style antennas... If there were you would not find 90 plus percent of agencies running some version of them. People (especially here) are going to tell you they are junk because they don't have any experience with them. With what you are doing you really should take your question over to P25.ca to get more solid answers from professional 2-way radio guys and not hobbiest (which is the majority of people here.)
(That's not a low blow to anyone here as there are some people who know. But trunked systems are their own animal and unless you have actually worked with them it's hard to diagnose what is going on.)

I can get 40-60 or more miles away from sites on UHF and 800 trunked running PCTEL's version of the phantom on UHF and 7/800. The RSSI values I see on a quartarwave 800 vs a PCTEL phantom is nonexistent.

If the antenna got +12 you more than likely fried the circuit board that is inside of the radome.

I actually work with trunked systems and this sounds like a programming issue to me. Almost sounds like a duplicated ID. For some reason your mobile is loosing affiliation with the site and therefor not receiving.

Feel free to shoot me a PM.
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Old 09-14-2016, 10:15 AM
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I run an 800MHz trunked system, also, and I've tried the phantoms side by side with 1/4 wave whips.

On 800MHz, there really isn't much of a difference in performance between a 1/4 wave whip and a phantom style. Since the antenna size is roughly the same, there isn't really an advantage. On the other hand, a 1/4 wave whip is a lot cheaper than a phantom antenna. I've got a few phantoms out in the field in applications where it made more sense, but generally I won't spend more money on a "cool looking" antenna. 1/4 wave whips work just fine in my application and the cost savings adds up when looking at lots of installs. But, too each his own. Some are more into image than performance or cost.

On UHF, they are OK.

And I don't care what anyone says, on VHF, they just plain suck. That's been proven time and time again. You can't cram an 18" whip into a 4" soup can antenna and expect it to work. Every one I know that has tried one has removed it after a few days and replaced it with a 1/4 wave whip. You can't cheat physics.



Seeing, or not seeing, a difference between one vehicle and another with different antennas isn't a very fair comparison. Expecting a 3dB whip to drastically outperform a phantom antenna isn't a realistic expectation. Under identical conditions, a 3dB whip is only going to see a 3dB difference when compared to a 0dB phantom (or whatever they claim). 3dB doesn't make a whole lot of difference on the receive side.
Add in things like different ground plane, mounting location, feed line losses (more pronounced at higher frequencies) and you'll see differences between any two installs if they are not identical.

Now, I have to ask the question, why are you swapping antennas? Shouldn't the state have their shop maintaining your equipment? Not very common to have individual officers responsible for install and programming of their own radios. This raises a red flag in my mind.
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Old 09-14-2016, 10:18 AM
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Quote:
Originally Posted by TLF82 View Post
With what you are doing you really should take your question over to P25.ca to get more solid answers from professional 2-way radio guys and not hobbiest (which is the majority of people here.)
(That's not a low blow to anyone here as there are some people who know. But trunked systems are their own animal and unless you have actually worked with them it's hard to diagnose what is going on.)

... and P25.ca isn't there anymore. You need to go to https://communications.support
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Old 09-14-2016, 10:22 AM
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Originally Posted by mmckenna View Post
... and P25.ca isn't there anymore. You need to go to https://communications.support
It always redirects for me. I was just being lazy and not typing out the new address. The coffee had not fully taken effect yet.
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Old 09-14-2016, 10:30 AM
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Originally Posted by mmckenna View Post
I run an 800MHz trunked system, also, and I've tried the phantoms side by side with 1/4 wave whips.

On 800MHz, there really isn't much of a difference in performance between a 1/4 wave whip and a phantom style. Since the antenna size is roughly the same, there isn't really an advantage. On the other hand, a 1/4 wave whip is a lot cheaper than a phantom antenna. I've got a few phantoms out in the field in applications where it made more sense, but generally I won't spend more money on a "cool looking" antenna. 1/4 wave whips work just fine in my application and the cost savings adds up when looking at lots of installs. But, too each his own. Some are more into image than performance or cost.

On UHF, they are OK.

And I don't care what anyone says, on VHF, they just plain suck. That's been proven time and time again. You can't cram an 18" whip into a 4" soup can antenna and expect it to work. Every one I know that has tried one has removed it after a few days and replaced it with a 1/4 wave whip. You can't cheat physics.



Seeing, or not seeing, a difference between one vehicle and another with different antennas isn't a very fair comparison. Expecting a 3dB whip to drastically outperform a phantom antenna isn't a realistic expectation. Under identical conditions, a 3dB whip is only going to see a 3dB difference when compared to a 0dB phantom (or whatever they claim). 3dB doesn't make a whole lot of difference on the receive side.
Add in things like different ground plane, mounting location, feed line losses (more pronounced at higher frequencies) and you'll see differences between any two installs if they are not identical.

Now, I have to ask the question, why are you swapping antennas? Shouldn't the state have their shop maintaining your equipment? Not very common to have individual officers responsible for install and programming of their own radios. This raises a red flag in my mind.
Completely agree with what is said here. I've seen much better results with PCTEL antennas vs the Laird versions. I've tried both and every model they make. All my installs now that call for low profile receive PCTEL antennas.

Yes the UHF is somewhat of a compromise over lets say a collinear antenna. But as long as you are not expecting to talk super long distances via simplex then you won't have any issues.

The VHF phantom antenna is definitely a joke. I personally think the only place they have is for a DVRS type setup. But I would still rather have a 1/4 wave antenna.
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Old 09-14-2016, 2:10 PM
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Quote:
Originally Posted by mmckenna View Post
I run an 800MHz trunked system, also, and I've tried the phantoms side by side with 1/4 wave whips.

On 800MHz, there really isn't much of a difference in performance between a 1/4 wave whip and a phantom style. Since the antenna size is roughly the same, there isn't really an advantage. On the other hand, a 1/4 wave whip is a lot cheaper than a phantom antenna. I've got a few phantoms out in the field in applications where it made more sense, but generally I won't spend more money on a "cool looking" antenna. 1/4 wave whips work just fine in my application and the cost savings adds up when looking at lots of installs. But, too each his own. Some are more into image than performance or cost.

On UHF, they are OK.

And I don't care what anyone says, on VHF, they just plain suck. That's been proven time and time again. You can't cram an 18" whip into a 4" soup can antenna and expect it to work. Every one I know that has tried one has removed it after a few days and replaced it with a 1/4 wave whip. You can't cheat physics.

Seeing, or not seeing, a difference between one vehicle and another with different antennas isn't a very fair comparison. Expecting a 3dB whip to drastically outperform a phantom antenna isn't a realistic expectation. Under identical conditions, a 3dB whip is only going to see a 3dB difference when compared to a 0dB phantom (or whatever they claim). 3dB doesn't make a whole lot of difference on the receive side.
Add in things like different ground plane, mounting location, feed line losses (more pronounced at higher frequencies) and you'll see differences between any two installs if they are not identical.

Now, I have to ask the question, why are you swapping antennas? Shouldn't the state have their shop maintaining your equipment? Not very common to have individual officers responsible for install and programming of their own radios. This raises a red flag in my mind.
Alright so the 3dB gain isn't so much for receive, but for transmitting? Yes it was on the same type of vehicle, using the same type of radio, with the antenna installed in the same location on the roof, however you are correct different year of vehicle and installed differently as far as wiring and other equipment inside the other vehicle.

As far as raising red flags, I don't work for the State of Kansas. I'm a county deputy. I do the installs for the county and although I do not personally program radios I set up the appointments to do so and communicate with our Motorola dealer. Basically I came here seeking help because our Motorola dealer is out of ideas on what could be wrong with my radio and we would have to get it sent in to the actual Motorola company to see if they can find anything wrong. Problem with that is the county would then be out $500 dollars if they find anything or not. Plus I would be without mobile unit then. You can find some of my installs on youtube if you would like to confirm. In fact here is the vehicle in question. https://youtu.be/ACut85SRjs0
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Old 09-15-2016, 9:34 AM
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I would have the radio tuned. Preferably done by a analyzer that can preform an auto tune.
If that does not fix it I would look at programming. It really sounds like to me that the radio has a duplicated ID. Or something else in the programming is wrong for the system itself. A single thing off and the radio will appear to be working but won't receive. Something as simple as having it not set to say omnilink.

The antenna is not an issue unless it's toast. If you have an RSSI of over 50 you should be hearing the system without any major issue.
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Old 09-15-2016, 9:43 AM
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Quote:
Originally Posted by kparr_90 View Post
As far as raising red flags, I don't work for the State of Kansas. I'm a county deputy. I do the installs for the county and although I do not personally program radios I set up the appointments to do so and communicate with our Motorola dealer. Basically I came here seeking help because our Motorola dealer is out of ideas on what could be wrong with my radio and we would have to get it sent in to the actual Motorola company to see if they can find anything wrong. Problem with that is the county would then be out $500 dollars if they find anything or not. Plus I would be without mobile unit then. You can find some of my installs on youtube if you would like to confirm. In fact here is the vehicle in question. https://youtu.be/ACut85SRjs0
I think you are officially out of options.
Your Motorola shop should have tested your antenna and feedline. That should have been an elementary first step. That would easily rule out issues with the antenna, coax, connectors, etc.
Once that is out of the way...
The radio should be benched for an alignment checkup. That would include checking the receiver and transmitter.
If something failed, they would/should repair it. If they can't repair it, then they'd send it to depot for repair, but they should at least know what they are sending it in for.

I understand what you are saying, but it sounds like your Motorola shop has a bad case of the fails. To claim they have no idea what's going on and want to depot the radio without knowing why raises more questions. Then again, after years of dealing with Motorola, I'm not surprised.

What you need is a second opinion. Take the radio and vehicle into a different radio shop and get it tested by someone competent in troubleshooting radios. There shouldn't be so much ambiguity about this. Issues should be readily apparent with some basic testing.
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Old 09-18-2016, 5:50 PM
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If it was me, first troubleshooting step would be put a mag mount with a 1/4 whip on that radio, THEN see if the problem still exists.

We already know that there was a good chance that the antenna and its coax took an electric shock. That could have caused any number of problems. Damage to the antenna's printed board is only one possibility. Could have also damaged the solder in the mount, could have damaged the coax itself.

If the problem exists with a completely separate antenna and coax, then its time to hand the radio to professionals. Preferably GOOD professionals.
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Old 09-18-2016, 6:31 PM
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Do you have a MDC/MDT in the vehicle that uses an aircard?
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