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FM Radio antenna connector location?

Discussion in 'Gen 2 Prius Technical Discussion' started by NeoPrius, Sep 11, 2008.

  1. NeoPrius

    NeoPrius Member

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    Anyone know exactly where the FM radio antenna connector is (2008 Prius) and how easy is it to get access to? Specifically, if you follow the coax from the radio to the antenna, I'm looking for the first standard FM coax connector.

    Been looking around on the forum and also in the service manual, but can't seem to pinpoint the exact location and/or access point.


    (Edit: I guess I should have put this thread in the Audio & Electronics Forum. Sorry about that.).
     
    #1 NeoPrius, Sep 11, 2008
  2. KK6PD

    KK6PD _ . _ . / _ _ . _

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    Hi there, well the first place I would start looking is at the back of the radio. I found mine in about 12 seconds after I opened up the dash for the first round of Mods! It has a standard "Motorola" type car radio connector thats been around for a while now!! It routes up the passenger side of the car and ends up dead center top back of the roof!!!
    I placed a RF splitter in line so I could use the antenna for a scanner thats also in the dash! The cable was VERY EASY to find!!

    As far as a standard "Coax" connector all your going to find is the Motorola at the radio. There are no BNC's, TNC's, SMA's, N's, F's, or PL-259's in line

    Good Luck de Pat KK6PD
     
    #2 KK6PD, Sep 11, 2008
  3. NeoPrius

    NeoPrius Member

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    Hi Pat, I'm going to insert one of those little multiplexer gizmos in the AM/FM antenna line that will allow you to us the regular AM/FM Radio antenna for a CB radio antenna while not significantly affecting broadcast radio reception. The little antenna multiplexer is similar to the one at the bottom of this page: Antenna Couplers for AM/FM/CB Radios and Scanners (warning: see the edit at the bottom of this post)

    The Prius radio antenna is obviously an electrically short antenna for CB, but the gizmo has a little antenna tuner to help tune the CB band return loss to an acceptable level.

    I could mount a big whip on the back of my car, or install a mobile ham radio, etc, but I'm not interested in that. I'm just looking for enough CB reception to hear the truckers talking about where the accident is when the traffic is backed up for miles in front of me. There's no torture worse than being stuck in miles and miles of traffic with no escape, wondering how far ahead the accident is and when the road is going to open up... :)

    I know I can tear the dash apart and follow the antenna wire from the back of the AM/FM radio to the nearest connector. What I'm trying to do is size up the scope of the job and whether I can do it in an hour or is it going to take me all day. Is the antenna connector built into the chasis of the AM/FM radio? Does a 6" antenna wire stick out the back of the AM/FM radio with a connector on it? Does the wire from the AM/FM antenna go all the way from the car roof to the AM/FM radio with just one connector in between... if so, exactly where is that connector located? Since you've been in there, can you describe what you've seen? I have the service manual, so I know where the wires route. But the service manual does not show the connector locations for the antenna wire.

    I didn't expect there to be any high quality RF connectors in the line. The standard el-cheapo AM/FM radio antenna connector is called a "Motorola" type connector? I've never known the name of it. I'm pretty sure the AM/FM antenna wire must be a coax - at least all the ones I've ever seen are.

    Anyhow, any descriptive information you can give me would be greatly appreciated.

    EDIT:
    WARNING - DO NOT USE THE PRIUS ANTENNA AS A CB ANTENNA USING THE COUPLER DESCRIBED ABOVE!!!
    Unfortunately, there is an inline antenna amplifier between the radio and the prius antenna base. The antenna amplifier is located in the headliner above the passenger side back seat. Transmitting through this amplifier would (a) not work, and (b) probably ruin it, therefore (c) you'd have to replace it and it would be a (d) real pain in the nice person to change.
    http://priuschat.com/forums/prius-modifications/34515-antenna-mod-3.html#post713499
     
    #3 NeoPrius, Sep 12, 2008
  4. KK6PD

    KK6PD _ . _ . / _ _ . _

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    Hey NeoP how ya doing, well I happen to have used the same company for my splitter, I have the BNC / Mororola out conns. As far as getting to the cable, read the following article. It is a very good description as to how to get your dash apart!!!

    https://www.metrotpn.com/documents/PDF%20Files/Prius/Eddie%27s%20XMRadio%20Install/PriusXMradio3.2.pdf

    Just follow the disassembly instructions, and you should be fine.

    Now on the CB issue, you realise that reception will not be that bad, however transmit could be a problem. I hope you have access to a VSWR meter for CB freqs. You will need to check the VSWR ratio! The reason that I say this is I am not sure if the antenna cable has a true 50 ohm impedance, for one, and second the antenna like you stated is not cut anywhere near to a 27 Mhz resonant operation. You could conceivably have a 3:1 swr and most of your power is going to be reflected back down your transmission line and cause all sorts of problems. Such as RF crap getting into the stereo, or worse! On the plus side, you only have 5 watts MAX that is allowed on that band. If you are not going to talk alot, just listen, you should be OK! As much as you do not want to put another antenna on the car, there are small Mag Mount antennas, as well as small base loaded whips that would look fine and not be a real pain in the nice person!! I have a 2m/ 440 whip on the back of my Prius and it looks fine. Its all black and blends in quite nicely!!!

    Good Luck with your quest, its going to be a interesting install!!

    Post some pics!

    73 de Pat KK6PD
     
    #4 KK6PD, Sep 12, 2008
  5. NeoPrius

    NeoPrius Member

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    It will take me a while to get around to it. I'm sort of in the investigative stage right now. I do have a cross needle meter for my HF rig (Yaesu FT-847) that will enable me to tune the VSWR, but only roughly because the meter is made for 200W and 5W is at the very bottom of the scale.

    Also trying to figure out what radio I'm going to use. Was going with a Uniden 520, but can't figure out a good place to mount it, so I was thinking a Midland 75-822 handheld with a car adapter. It would fit nicely into the upper glove box and I could just pull it out when I need it.

    Thanks. I will post something when I get it all worked out.
     
    #5 NeoPrius, Sep 12, 2008
  6. alanh

    alanh Active Member

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    Depending on how large your hand is, there's an alternative to getting to the back of the radio besides disassembling the whole dash. You can remove the lower glove box and the A/C vent to the left of it. You can then remove the bolt in the big white junction block behind the vent.

    Once it's loose, there's enough wiggle room to get your hand behind the radio. You'll have to do everything by feel, of course.
     
    #6 alanh, Sep 15, 2008
  7. NeoPrius

    NeoPrius Member

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    Unfortunately, it turns out you can't use the Prius antenna as a stealth CB antenna since there's a little AM/FM antenna amplifier between the radio and the Prius antenna base. It is located on the passenger side above the rear seat.

    Will have to figure something else out...
     
    #7 NeoPrius, Oct 8, 2008
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Also, I understand that the antenna base itself contains a PCB with an amplifier.
     
    #8 Patrick Wong, Oct 9, 2008
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