FLT Cascadia and other co-phased setup with FM diplexer

Discussion in 'CB Radio Forum' started by frenchy, May 1, 2011.

  1. frenchy

    frenchy Bobtail Member

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    May 2, 2008
    Ranson, WV
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    Got into a brand new cascadia and since my old CB was dead I bought a new cobra 29LX LCD. ( same as a 29LTD but with a different face plate)

    Anyway, I the CB gives me a ANTENNA WARNING and I cannot calibrate it. I do not want to TX anything until I fix the antenna warning issue.

    Basically, the CB cable ( mini-8 split into 2 cable under the driver side cover) goes down underneath the DASH where it is plugged to a FM/CB diplexer.

    That box is responsible for a reflect to the CB and makes the CB believe the antenna is way too short, thus the warning.

    It seems to be the case for a lot of new cascadia's out there. did anybody sent their truck back to dealer to get this fixed ? and if so did they care enough to fix it.

    Or should I make a choice between CB or FM and bypass this box altogether.
     
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  3. WA4GCH

    WA4GCH Road Train Member

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    Seminole Florida
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    What it is supose to do is act as a low pass filter and antenna tuner for CB and a high pass filter for your FM radio. These are commonly used on multiband ham radios like the IC-706 when using mulitband antennas.

    What it sounds like here is they are tring to use your FM antenna for both FM and CB and if built RIGHT would work just fine HOWEVER on CB it would not be a very good system ..... IF I was you I would see if I could install a CB antenna with it s own coax for youe CB and just leave the box for your FM radio.

    IF it has no tuning ajustments for the CB radio there is no way its going to work right ....
     
  4. Gadfly

    Gadfly Medium Load Member

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    WA4GCH is absolutely correct. In almost every case, the common "CB/FM" diplex thingy doesn't work and leads to poor performance, receiver degradation and high SWR. There is no substitute for a GOOD, well-performing CB antenna, separate from any other equipment.

    GF
     
  5. SLCTrucker

    SLCTrucker Medium Load Member

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    Salt Lake City UT
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  6. Yup

    Yup Medium Load Member

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    Everywhere,USA(Texas)
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  7. WA4GCH

    WA4GCH Road Train Member

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    Buy a antenna with some coax and be done ......
     
  8. Rat

    Rat Road Train Member

    I have been through two trucks that had a similar setup. Volvo and the 04 379 pete that I amn currently running. Now my fix was easy due to the available mirror brackets on both trucks. Get some coax and clamp on antenna mounts, route the coax properly and clean mirror brackets, install mounts with seperate antennas and you are good to go. Leave the stock system in place so that you still have am-fm radio reception.

    I am hoping that my next truck will be a Kenworth as they don't use this setup. The t 8s and the W9s that we have, have a seperate antenna for the am-fm radio, in the center of the roof.
     
  9. WA4GCH

    WA4GCH Road Train Member

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    RAT .....

    Morning ....

    I have had little luck with the "BOXES " nothing beats a stand alone CB antenna .....
     
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