Replacement electric antenna advice sought (77 308) | FerrariChat

Replacement electric antenna advice sought (77 308)

Discussion in '308/328' started by decampos, Jul 24, 2006.

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  1. decampos

    decampos Formula Junior
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    #1 decampos, Jul 24, 2006
    Last edited by a moderator: Sep 7, 2017
    Hi Everyone, I was spending ages looking through the archives when I probably could get away with asking the question outright:

    My original 308 Autovox antenna died last night, I bought a replacement today - I couldn't find a 'semi-automatic', only a 'fully'. Is there any way I can easily set this up to work as the original did? There's talk about the board of needing a couple of diodes but I'd need a bit of hand holding I think. In the archives there's lots about this but without photographs (they're mostly missing/deleted) and not much about the procedure (baring in mind I'm fairly dopey with electrics).

    Any help appreciated
    Thanks
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  2. decampos

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    actually, this should probably be in the technical area. Is someone could move it there I'd be most grateful.
     
  3. decampos

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    don't all rush ...
     
  4. FasterIsBetter

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  5. decampos

    decampos Formula Junior
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    Thanks Steve, I appreciate your help but this is what I was talking about - on that link there are helpful photographs missing (blank placeholders on my browser) - particularly the ones showing what the new connections look like. the search function is sometimes only half useful.
     
  6. Verell

    Verell F1 Veteran
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    Sorry,
    It's not search per se.

    The Fchat hard drive crashed a couple of years back, all the threads were recovered, but about half the pix were lost.

    I think I may have the pix with the diodes somewhere, will post it i can find it.
     
  7. decampos

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    ahhh, I've often wondered why that was. I thought it was the posters deleting the attachments. 'Why would they do that?' I thought.

    Thanks Verell, that would be great.
     
  8. FasterIsBetter

    FasterIsBetter F1 Veteran

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    p.s. -- I bought one of the Harada semi-automatic replacements for my old Mondial QV about 2 years ago and installed it. IIRC, it went in no problem and wired up easily. Got it from antennaworld.com.
     
  9. wolftalk

    wolftalk Formula Junior

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    considering he's already got the antenna....

    You have a couple options...you can rewire the antenna or play with diodes. Both techniques are on this thread:
    http://www.ferrarichat.com/forum/showthread.php?t=67638&highlight=metra+antenna

    In the diode technique, the radio red wire would go to the two diodes, and the green wire to the single diode. You'd either need to use a meter to figure out which ferrari wire is +12V when the switch is in the up position, or guess and swap them if you get it wrong.

    I thought rewiring was easier, so went that route.

    if you aren't sure, take a picture of the back side of the unit showing the relay and where the wires from it enter the antenna case.

    If the black wire is not going into the relay with the red/green wires, the referenced thread is not relevant. If that's the case, see if the radio instructions have a schematic and post it.
     
  10. decampos

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    Hi Phil, thanks for this. I bought some diodes today so I'll probably go down that route.

    My understanding of this kind of thing is really limited. the most I've ever done is wire pickups on a guitar.

    let's unpack this:
    On my car I'm pretty sure the toggle on the center console kicks out two live wires (up and down are both +12V) Do you mean for getting the up position to go up and not down or are you talking about a different type of switch? When you say 'goes to two diodes' what do you mean? two diodes end to end?

    Sorry for not being up on this.
     
  11. wolftalk

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    #11 wolftalk, Jul 25, 2006
    Last edited by a moderator: Sep 7, 2017
    there's two wires coming from the console switch. The provide both +12V and ground directly to the antenna motor. All the switch does is swap which wire has which. Since it's a dc motor, swapping polarity changes the direction the motor spins. There is no other ground connection needed.

    the automatic antenna is different. When there is +12V on the green wire, the antenna goes up...all the way. Remove the +12V on the green wire, the antenna goes down...all the way. The red wire always has +12V, and ground is coming from the chassis. Swapping the polarity on the motor and more importantly disconnecting the power when the motor is all the way up/down is handled by the relay and and a mechanism inside the motor.

    looking at it from a voltage perspective, the diodes let the console switch put +12V on the red wire in both switch positions, and +12V on the green wire only in one switch position. The ground path from the console switch is not used.

    Since you can let go of the switch anytime and disconnect the +12V, the antenna behaves like the original.

    to make a tidy job of it, you connect the diodes as shown in the picture and add the spade terminals, then plug the ferrari wires in. I assume you could remove the red and green wires and connect the diodes directly to the relay solder lugs, but however it's convenient to package it up is fine...and this does present an opportunity to use duct tape somehow.

    My take was that if I'm going to have to put in spade connectors anyway, I might as well not use diodes, get rid of the relay, and bung the spade connectors directly onto wires going to the motor. Plus, I win antenna races because I don't have a 0.7V drop across a diode :)
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  12. decampos

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    Hi Phil. Thanks for taking the time to do this. I'll get on to this tomorrow first thing. Just one dumb question: what do I do with the black ground wire from the new antenna? Can I just connect that to the grey flat wire that was attached to the original antenna?
     
  13. wolftalk

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    that'd work, though you'd be connecting a ring terminal to a spade connector, which isn't very reliable.

    The black wire is a ground wire, so you can attach it to any convenient bolt in the chassis...as long as the bolt is not somehow insulated from the body/frame metal. e.g. bolts holding in the lamp assemblies are probably not good.

    the other end of the grey braided strap is attached to a chassis bolt someplace, so ideally you remove the strap and connect the black wire to the same place. I vaguely recall that it's under the carpeting down at the bracket that holds the bottom of the radio, but my memory is pretty unreliable.

    before bolting up the new antenna, connect the wiring and make sure it works as expected. If you put something back together before testing, it inevitably won't work.

    If it doesn't work, or a fuse blows, take a picture of how things are connected, including the wires going to the relay and the wires from the relay going into the antenna, and post it back here.
     
  14. decampos

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    #14 decampos, Aug 9, 2006
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  15. Verell

    Verell F1 Veteran
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    Phil,
    Is that black bag around the antenna motor original? Don't think I've ever seen one before.

    I assume that your car is a Euro model from your location. I've got an '82 Euro GTS QV & my antenna motor was out in the open when I got the car. Also, looks like there's a piece of carpet with some kind of hardware on it behind the antenna. I don't have that hardware, just a carpet lined pocket.

    BTW, there should be a drain tube to the fitting on the bottom of the motor, otherwise you'll be getting a bit of water inside that pocket the antenna sits in.
     
  16. decampos

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    Hi Verell. I assume you mean me. It's actually a US spec 308, the hardware is the inner housing of one of those useless ugly red lights you won't have on a euro car. really annoying losing that extra space. I assume the bag (more a flap that wraps around the antenna and snaps tight) is original as it's made from the same material as the zippy top bit of the boot. I don't think I've ever seen another one though. Thanks for reminding me about the plastic tube, I forgot to put it on. Terrible reception on the new antenna by the way.
     
  17. Verell

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    Tnx for the response,
    Funny thing, as scarce as Euro QVs are, there are 3 in this area, & are the cars I'm most familiar with as mine is one of them.

    That little antenna bag looks a lot better than the antenna motor sticking in mid-air.

    One of these days I've got to have another go at noise reduction. I get terrible AM reception, alto FM is OK.
     
  18. 308 GTB

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    #18 308 GTB, Aug 10, 2006
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  19. Artvonne

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    Make sure your car has all the noise suppresors/condensors installed. I see on both my cars they all seem to be missing when I look over the wiring schematic. That flat grey wire referenced earlier is webbed mesh uninsulated ground wire that is used to statically ground the radio antenna, but I was not aware it went all the way back to the radio. Maybe someone cut it off both my cars? I believe the original battery ground cable on these cars was simular and most have been replaced with standard battery cable. The motor should have TWO heavy mesh flat ground straps to the frame. Again, some think these cables are crap and replace them with standard cables, but the idea is the flat mesh open grounds will disipate spurious static elecrical impules's into the surrounding atmosphere and clean up radio reception. Primarily thier should be suppresors on the ignition coils and alternator, and any other motors you dont want to hear on the radio.
     
  20. Verell

    Verell F1 Veteran
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    Thanks for the post Paul,

    I'm an EE & worked for a radio/TV shop for years in high school & thru college, also did EMI suppression designing computers for DEC. So know the tricks. Just need to get radio noise suppression high enough on my 308 Round2It list to put effort into it...

    I'm sure it will help someone else tho.
     
  21. JulioM75

    JulioM75 Rookie

    Jan 15, 2024
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    I like this and have been trying to inform people that using a Single diode works great.

    On yours those you don't need three diodes you only need one. two yes is ok for safety. However that safety is not really needed.

    With 1 the red will back feed to the switch but the switch on that sid will be open. If that wire had any issues with grounding out it will have shorted out and the fuse would have blown. Even if the issue of that wire grounding out happens while the up/green wire is active the fuse will still blow. So you only need one diode. From Green/Anode to Red/Cathode.

    I have a video that I am still in editing showing this.
     

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