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Thread: 1 Radio 4 bands, 3 antennas

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  1. #1
    Join Date
    Sep 2005
    Location
    I hope someplace in the Visayas
    Posts
    921

    Default 1 Radio 4 bands, 3 antennas

    1 FT8900R
    2 CR627B triband 2m/6m/440 antenna
    3 Comet SBB7 Dual band antenna
    3 10m antenna


    I dont want to lose my 800mhz recieve for our area law enforcement otherwise I would just use a duplexer/combiner/splitter (pick your choice of nomenclature) and use 2 antennas. The triband and a 10m antenna. But the duplexer will kill the 800 recieve.. Soo how about using a triplexer and a duplexer. The FT8900R would output into a Comet 4310c triplexer. LPF is 1.3mhz to 150 BPF is 350mhz-500mhz and HPF is 840-1400 mhz. The SBB7 would connect on the HPF to work as my recieve antenna on 800mhz. Yes I know its not a dedicated 800mhz antenna but it actually works fairly well, as I had used it before I got the triband antenna. No antenna will be connected to the BPF output, and the LPF will feed a Comet CF530 duplexer. I can then split the triband antenna on 1 output and the 10m antenna on the other output. I know it sounds overly complicated and it probably is, sooo any suggestions, The quad band antenna for the 8900R isn't an option.. The other option is a 2nd radio just for 10m. I do have a radio shack HTX-10 I "could" put in the car but I dont know if I really have enough room for it.

  2. #2
    Join Date
    Jan 2008
    Location
    St. Mary's County Md since 2000
    Posts
    8,162

    Default

    I would put the Comet 2m/440 antenna on one side, and the 10m/6m antennas on the other side with a two position manual switch.

  3. #3
    Join Date
    Jul 2007
    Location
    Topeka, KS
    Posts
    615

    Default

    While I can't say how well it would work, having never used du/di/tri-plexers, I can say that you will not be able to use the 70cm band with that setup.
    Since you said that the triplexer will be the first link in the chain, and the 350-500MHz output will have nothing attached, then your 70cm RF will dump into an open port, with it's high SWR and ruin the 70cm output on the radio.

    Other than that, it does appear that this would work, except as above, and were I you, I would put a dummy load on the 70cm port of the triplexer, just in case. Doesn't even have to be a fancy one, just a cheapo one with a rating of 20W or so (because they can derate to higher power for short periods), like a Diamond DL30.

    Personally, I think you'd be better off selling the SBB7 and getting a cheap scanner with the money plus what you would have spent on one of the plexers.
    It'd work better, scan faster, and have all the trunking features, along with the benefit of using the 8900 for what it's best at: covering the amateur bands.
    If your LEO's don't use trunking, so much the cheaper for a scanner.
    Not to mention that you'd be able to cover a lot more spectrum with the scanner. There's always interesting stuff out there; the bigger the city you live in, the more interesting the traffic.

    -Edit-
    Also, if you were worried about overloading the scanner, you can build your own high/low/band-pass filters with a handful of components built into a metal box. Maybe cost you $2 plus shipping for parts and whatever the box costs; or you could build your own box out of double sided PCB.
    There was an article about doing just that in CQ magazine about a year ago. It was originally inteded for computer TV tuner cards (or set top boxes) for OTA reception, but is easily adaptable to cover whatever range you want.
    I built one for my tuner card and it works great; I rarely drop picture anymore.
    Last edited by K0SPN; 04-19-2012 at 04:18 PM.

  4. #4
    Join Date
    Sep 2005
    Location
    I hope someplace in the Visayas
    Posts
    921

    Default

    Yeah I flubbed forgetting abt the UHF recieve. I will probably just end up using a dedicated 10m radio and antenna and calling it good. I was looking in the car today and I can probably squeeze my HTX-10 in someplace..

  5. #5
    Join Date
    Jan 2000
    Location
    Commerce MI (Detroit area)
    Posts
    8,327

    Default

    I would be leaning towrd a high quality Coax Switch and forget lossy triplexers.
    73.....JD, FISTS #3853,cc 455,SKCC # 1395,tribune #12,
    Official US Taxpayer

  6. #6
    Join Date
    Sep 2005
    Location
    I hope someplace in the Visayas
    Posts
    921

    Default

    Actually the duplexers aren't that lossy .2db maybe. One of the Alpha Delta coax switches had .5db at 440 mhz...

  7. #7
    Join Date
    Sep 2005
    Location
    I hope someplace in the Visayas
    Posts
    921

    Default

    Actually the duplexers aren't that lossy .2db maybe. One of the Alpha Delta coax switches had .5db at 440 mhz...

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