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Thread: APX Multiplexer question

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    Default APX Multiplexer question

    I could have sworn Iíve seen a Moto document that stated that the Motorola multiplexer that can be ordered with the APX8500 will support three single radios to one antenna (like most fro/multiplexers do). Moto documentation and the support desk has no idea. They only see the stuff as it pertains to an 8500 for radio to three single antennas.

    Can this be used in this manner? End game is a V/8 APX7500 and a UHF XPR to one multiband antenna


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    Finding a multiband antenna that provides a good match on all 3 bands would be a challenge. As far as coupling the 2 radios to one antenna it can be done but the multicoupling is going to cost a fortune since you need to pass the selected radio band and reject the other two for each RF output you have.

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    This is what happens when people including Motorola don't use the right terminology.

    Combining radios on different bands to one antenna or combining antennas on different bands to one radio is done with a diplexer.

    Combining a receiver and a transmitter together in the same band is done with a duplexer.

    Combining transmitters together into one antenna at a repeater site is done with a combiner (low loss cavity types for wider tx frequency spacing a or more lossy hybrid types for small spacings).

    Combining multiple radios in the same band (typically at a dispatch center) is done with a control station combiner, these are very lossy, at least 75% of the transmitter power is thrown away as heat but they do work.

    Sounds like a control station combiner is what you want and the leader in that field is dBspectra.
    Last edited by Astro Spectra; 1 Week Ago at 06:44 AM.
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    Quote Originally Posted by orangekitty56 View Post
    I believe this is what he is referring to, in which case it should work.

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    OP wants to put VHF, UHF and 7/800MHz on one antenna.

    Don't need a control station combiner for that. The OP needs the aforementioned "Multiplexer" that Motorola offers, which is in fact actually a "triplexer", but alas, Motorola has to call it something proprietary.

    $200 for that? Not bad...
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    Correct. All I want to know with certainty is that Motoís version does work like everyoneís elseís, and I wonít be dumping 100 watts of APX into the XPR.

    1-800-Moto has zero documentation with the telephone drones and they are only fixated on what the 8500 install manual has.

    There is some block diagrams with the Futurecom DVRS in using them for some funky configurations but Iíve yet to come across anything or anyone that states or has tested them to confirm.

    I donít have a service monitor handy to test the isolation to use and ensure Moto work the way everyone elseís does.

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    That EQ000103A02 in the link is for connecting 3 different band antennas to one APX8500. I see nothing to suggest it would offer anywhere near enough isolation to prevent a transmitter from frying the other two receivers the first time it is keyed up. Duplexers are big for a reason...
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    I was able to get the spec sheet. 50dB isolation does the high power model. Attempting to post a screen shot.

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    I have 12 of EQ000103A02 on order. when they come in ill put one on my service monitor and see what the isolation is to run it backwards

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    Quote Originally Posted by Magnus View Post
    That EQ000103A02 in the link is for connecting 3 different band antennas to one APX8500. I see nothing to suggest it would offer anywhere near enough isolation to prevent a transmitter from frying the other two receivers the first time it is keyed up. Duplexers are big for a reason...
    Combiners, Duplexers are big because of the close spacing in band. With the exception of hybrids combiners.

    These (surprisingly cheap) Triplexers from Moto, are likely nothing more than tuned strip line circuits. It will work just as well either way.

    Back in the day, guys would use tuned pieces of coax stubs for a diplexer of sorts.
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    It's amazing that Motorola could not install three antenna connectors to the radio and instead has an over engineered $200 TRIPLEXER apparently lossy enough to rquire cooling fins.

    Comet and Diamond have long sold various models of Triplexer for Ham radio that work pretty well,

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    It appears it was made by amphenolprocom (guessing a subsidiary of Amphenol??) for Motorola.

    https://amphenolprocom.com/products/...80-520-760-960

    There is also a low power (30w) version. EQ000103A01 with no fins.
    https://shopwiscomm.com/EQ000103A01-...-P5828670.aspx


    Here is specs on both LOW and High Power Triplexes
    https://amphenolprocom.com/products/...80-520-760-960
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    EQ000103A02

    Attachment 13847
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