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2 Rig, 2 Amp, 3 Antenna Patch Panel

Discussion in 'General Ham Radio Discussion' started by tba02, Feb 14, 2016.

  1. tba02

    tba02 WOOF

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    I'm looking to be able to use 2 rigs (one or the other - not both at the same time) using 2 independent RF chains terminating at one of three antennas and a dummy load.

    I've created a patch panel diagram where I can keep them isolated and change rigs by swapping two patch cables. I'm pretty sure this will work out just fine, but I feel I have been staring at this way to long now. I'm looking for a sanity check.



    See any flaws or mistakes in this design? Input / feedback appreciated.
     

    Attached Files:

    fourstringburn likes this.

  2. fourstringburn

    fourstringburn W9WDX Amateur Radio Club Member K5KNM

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    If you don't want to make your own, consider the MFJ-4724 or the 6 position model 4726.

    This is an all in one electronic controlled radio/antenna switch box that let's you select up to one of 4 or 6 radios (dependent on the model) to any 4 or 6 antennas. It also has an independent common coax in/out auxiliary connections so each selected radio can pick up an TVI filter, or whatever else is needed in-line. However, if nothing is needed in-line, a small coax jumper is necessary from the antenna common port to the radio common port to close this circuit

    [​IMG][​IMG]
    The top selector knob is for antenna selections which you can patch a dummy load into one of them which is what I do.

    The lower selector knob is for choosing a radio to go with your antenna choices.

    I use this along with the optional small MFJ-4724RC desktop remote switch so I can keep this switch-box under my desk and out of the way and control it with just a small desktop remote.

    [​IMG]
     
    Mudduckmobile likes this.
  3. tba02

    tba02 WOOF

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    Thanks. I'm leaning toward the patch panel for several reasons. If I use my design - and always have the connections in place - I am ensured that each radio has either an antenna or a dummy load connected which in theory will minimize user error. I also think it affords better isolation between the RF chains - in theory anyway. Cost, the least of my concerns, is minimal as I have an old rack mount server switch that I will gut and use for mounting the SO-239 connectors. Therefore I I need to purchase are the bulkhead connectors and some PL-259's for the coax I have on hand.

    Who knows, maybe I will get lazy :)
     
  4. 222DBFL

    222DBFL Sr. Member

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    Mfj makes a 6 way antenna/radio switch combo that will allow all you are wanting to do. The one that fourstringburn posted. The top one. My local pal just got one to use 3 radios with his 5 antennas. Can use any combo of radio and antenna together. Pretty neat. He is using a kenwood 480sat, Icom 746, and 746 pro for radios. He has 5 antennas I know for sure. Maybe more. It's almost an antenna farm LOL!! But from all accounts the 6 way box is working far and no issues to report yet. Will let you know what comes of it here in a few weeks if you remind me LOL!!
     
  5. tba02

    tba02 WOOF

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    Thanks again, but I am more interested in a sanity check on the diagram posted. I'm looking at the homebrew option right now.

    However, lets say I was using the MFJ box - if I have 2 radios, A and B, and A is selected on the switch, what protection is offered if I mistakenly transmit on radio B?
     
  6. fourstringburn

    fourstringburn W9WDX Amateur Radio Club Member K5KNM

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    Put dummy loads on unused antenna ports.

    When I go to switch radios, I listen for static to be the first clue the right radio is selected.

    I use the 4 position MFJ 4724 with 3 radios and 2 antennas and a dummy load and works just fine.

    Obviously pay attention to what you're doing and you will be fine.

    It becomes 2nd nature soon enough.
     
  7. tba02

    tba02 WOOF

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    I get that, but it doesn't quite address the question. Let me rephrase.
    If I have the box set to Radio A -> Antennna ->A
    If I transmit on radio B, with the box set to A/A, what happens? Where does the RF from radio B terminate?
     
  8. StrangeBrew

    StrangeBrew Sr. Member

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    Not sure about the switch mentioned above but look up the MFJ-1703, only good for two radios and two antennas but always keeps each radio hooked to something.

    With the switch at position 1: radio 1 connects to antenna 1 and radio 2 connects to antenna 2

    With the switch at position 2: radio 1 connects to antenna 2 and radio 2 connects to antenna 1

    If you hook both radios to the MFJ-1703 you can put a separate switch for all of your antennas on one output and a dummy load on the other, this way switching either radio to the antenna farm will leave the other radio hooked to the dummy load.
     
  9. fourstringburn

    fourstringburn W9WDX Amateur Radio Club Member K5KNM

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    Transmits into a brick wall. You don't want to do that.

    Strangebrew mentioned the MFJ 1703 safety switch. I used one but it is not rated for high power so I replaced the stock slider switch with a higher current one. These are Ok between amps and radios otherwise.

    Whether you use a switch box or repatch like your schematic shows, you still can run the same risks of transmitter/amp damage by not paying attention to what you are doing.

    I do like your design by the way.
    .
     
  10. BBB

    BBB Well-Known Member

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    I've not had any luck with antenna switch boxes unless they were made of all cast aluminum with isolated switch gear. That cheap sheet metal box stuff with open switches is prone to RF bleeding and feed-back within the switch gear once you start running some real power.

    The Alpha Delta stuff is commercial grade and mil spec rated for real world 1500 PEP CW watts (not MFJ watts)

    https://www.alphadeltacom.com/pdf/DELTA-4B multi-connections-2.pdf
     

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