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Thread: XTS2500 SMA Failure Rate and Cause

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    Default XTS2500 SMA Failure Rate and Cause

    While I haven't had this issue; its a failure mode that does intrigue me. Whats the common failure rate of the PCB mount SMA for the XTS2500's? And what seems to be the common cause of this failure, lateral stress on the SMA jack or just general stress on the antenna itself?
    - Bryan
    "So the best solution is to paint them to blue color and throw them to the sea?" in reference to MTS2000 F01/93.


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    Quote Originally Posted by synegy3488 View Post
    While I haven't had this issue; its a failure mode that does intrigue me. Whats the common failure rate of the PCB mount SMA for the XTS2500's? And what seems to be the common cause of this failure, lateral stress on the SMA jack or just general stress on the antenna itself?
    My answer from experience makes me just say "yes".

    I maintained a fleet (approx. 150 radios) which were about 2-3 dozen XTS5000s and the rest XTS1500/2500s. The latter had more SMA issues than the first. However - I also worked in a setting where we constantly had users lose/break belt clips at a staggering rate, and no one wanted to use holsters. Therefore, a LOT of the radios were dropped onto steel decks frequently, or I'd see knucklehead officers/supervisors swinging the radio around by its antenna while juggling their 3rd coffee of the morning. So I saw a lot of antenna/SMA failures - but I attributed most of them to rough handling due to idiot users.

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    Quote Originally Posted by Navy_BOFH View Post
    My answer from experience makes me just say "yes".

    I maintained a fleet (approx. 150 radios) which were about 2-3 dozen XTS5000s and the rest XTS1500/2500s. The latter had more SMA issues than the first. However - I also worked in a setting where we constantly had users lose/break belt clips at a staggering rate, and no one wanted to use holsters. Therefore, a LOT of the radios were dropped onto steel decks frequently, or I'd see knucklehead officers/supervisors swinging the radio around by its antenna while juggling their 3rd coffee of the morning. So I saw a lot of antenna/SMA failures - but I attributed most of them to rough handling due to idiot users.
    Interesting. It would seem then the overall design choice of a PCB mount vs molded aluminum chassis was a poor one, based on the research I've been able to do; it would seem exactly as you described the vast majority of failures are caused by abuse or very hard rough usage.
    - Bryan
    "So the best solution is to paint them to blue color and throw them to the sea?" in reference to MTS2000 F01/93.

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    Where we are, the extended VHF broadband antenna contributes a lot. A lot of officers have 'Dunlap Disease'. There gut done laps over their belt!
    Apparently NOT a radio professional.

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    By far the worst for antenna connectors coming away from the PCB are the DP2k4/2k6 and XPR3k series. Only practical solution is to glue the antenna onto the case with epoxy.
    It is a fine thing to be honest, but it is also very important to be right

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    This is nothing new. I have had HT600 antenna tabs to the circuit board broken, loose and or broken HT1000 connectors, connectors broken loose on CP200s and CDM750s. I have even seen the circuit board under the connectors broken. If it can be broken, someone will.

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    That should be HT750, not CDM750 got my radios mixed up..

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    Out of curiosity I'm wondering what the most common band/antenna is for breakage. Since they vary in pliability is one more susceptible to SMA breakage over another?

    For instance an 800mhz whip vs wideband VHF. The base of the WB VHF is more robust and doesn't have a lot of give whereas an 800 meg whip seems a little more forgiving...
    Last edited by p25smartzone; Jul 31, 2018 at 06:48 PM. Reason: Added a word

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    Quote Originally Posted by p25smartzone View Post
    Out of curiosity I'm wondering what the most common band/antenna is for breakage. Since they vary in pliability is one more susceptible to SMA breakage over another?

    For instance an 800mhz whip vs wideband VHF. The base of the WB VHF is more robust and doesn't have a lot of give whereas an 800 meg whip seems a little more forgiving...
    My case above was all with the UHF whips or stubbies - though we went to whips because the stubbies were our suspicion for SMA breaks - however we didn't see a remarkable change in how many broke once we switched them all out.

    But if I had to be a betting man... the VHF wideband has to be the worst. Stiff and a mile long - plenty of leverage to break an SMA.

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    I would imagine that the VHF or stubby antennas given how they are all helical provide a larger solid molded area that pressure can be applied to, which seem to break the SMAs more readily. The UHF, 800 and 900 antennas, even though being whip antennas, have that solid base where the connector is that, if appropriate pressure is applied to I would imagine could easily break the SMA as well.
    - Bryan
    "So the best solution is to paint them to blue color and throw them to the sea?" in reference to MTS2000 F01/93.

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    Quote Originally Posted by p25smartzone View Post
    Out of curiosity I'm wondering what the most common band/antenna is for breakage.
    Low band SMAs. I think the Waris series used MX threaded stud antennas (wisely) but Kenwood TK-190s used SMAs... and they broke constantly.

    The mega-duck antennas used on European mid-band MX radios were done right... reinforced MX stud.
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    For anyone curious, yes, the Waris uses the gigantic stud connector.

    But, what is interesting, is in the back of the Waris manual, where accessories, batteries, and antennas are listed, it shows the usual Jedi/ASTRO/ASTRO25 whips with SMA connecters.

    I have a VHF 1550, and can confirm the wideband “dildo duck” VHF antenna works fine. Strange, but true.

    Now if you want to put an external antenna on to this radio, the adaptor is a screwball!

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    I remember the GP-300 had a very similar if not the same adapter. The board had a jack that switched the outer ring/screw terminal from antenna "hot" to ground when the 2.5 mm plug seated, it would open the RF to the ring and the adapter would short the ring to ground. So, with a stud antenna the ring was hot (RF) and with the adapter it was grounded and the center pin of the 2.5 mm was hot.

    I am curious about the antennas, though. By feeding the hot RF to the ground ring of an SMA antenna, it might apply the energy to the other side of a dipole, and the other normally hot side (center pin) simply floats unconnected. It's possible that the ground is somehow coupled to the center pin of the antenna by a capacitive or inductive method or network, and some energy leaks from the ground terminal to the center terminal, enough to work somewhat, but I can't think it would provide a good proper 50 ohm feed, and probably wouldn't work as well as a proper stud-type antenna. Interesting, though - some range test comparisons would be fun to see how they actually work.

    For some reason I thought the SMA and the stud antennas thread differently, no? I don't have any Waris radios to check out.

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    The XTS2500 SMA antenna failure certainly exists. Out of approximately 500 used UHF band XTS2500 radios we had about 10% with 'loose' SMA RF connectors. The failure mode is generally the PCB solder joint and SMA connector (ground) mounting points failing due to mechanical/vibration stress placed on the antenna. There is a varying amount of damage with some connectors having hairline solder joint cracks causing intermittent RF when a small amount of sideways force is applied to the SMA connector to those connectors where you can wiggle the antenna and feel the SMA connector moving around.

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    I just did a backlight restore job on a used gov. surplus XTS2500 UHF R1 radio for a friend. After taking the radio apart I found the antenna SMA connector to be sheared off the pcb. All four ground posts snapped off and some top side PCB file peeled off.
    The failure mode must have been the radio getting dropped antenna first on the ground.... the center pin had cracked free from the solder, but was still contacting the pcb just enough it was still functioning by just the force of the case holding it in place.
    After mod'ing the keypad board to restore the back light and installing the D501 top indicator LED, I replaced the SMA connector and the radio works fine - no worse for the wear.
    Moral of the story, don't drop your XTS on it's head.

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    VHF radios are subject to this when using the larger antenna. I attribute it 'Dunlap Disease'. The operators belly done lap over the belt and pushes on the antenna.
    Apparently NOT a radio professional.

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    I agree. Dunlap. Fixed numerous and the users were just that.

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