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Early semi-auto antenna question

Discussion in 'Technical Q&A' started by robertgarven, Dec 15, 2003.

  1. robertgarven

    robertgarven F1 Rookie
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    Friends,

    I am having a hard time getting functional the only thing has never worked on my car, the antenna. Dave H. was kind enough to send me some photos of his installation, but he has a 328 and I think the earlier cars had a different setup? First off I bought the antenna from antenna world and they were more than helpful and kind and I would recommend them to you guys. I think the problem is the way the gt4, and I would assume early cars were designed.

    Here is the problem. The switch on the gt4 has 3 wires, 2 that go to the antenna and one hot. The new semi-automatic antenna has two wires coming out of it and I am pretty sure it works by reversing the polarity of the motor. When I hooked it up straight nothing, but after talking to Mike F. here on F-chat he suggested that I try something and it worked. When I grounded one of the contacts from the antenna and one hooked up to one of the stock wires I could get it to go up, and by switching this set-up I could get it to go down. So basically my stock gt4 setup has two wires, when you push the switch up it send juice down one wire and when you push down it sends the juice down the other.

    It seems that the replacement antenna was designed to work with a switch that is grounded. In the interests of originality I cannot replace the switch, and all attempts at grounding the antenna failed. I am waiting for a call from Raul at antenna world so maybe they have an antenna that will work. I am guessing that I will need one that has 2 hot wires going to it and a ground? If any of you guys with early 308’s or gt4’s have solved this I would be interested in the solution.

    Thanks Rob
     
  2. f355spider

    f355spider F1 World Champ
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    Rob,
    Did you check the parts in the Ferrari UK web section on Ferrari Owner's Site? Are the antenna and switch different than on later 308's?
     
  3. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    My 308 is a 77 and appears to have the original switch which is a double pole double throw designed to reverse the polarity of the power/ground to the antenna to raise and lower. The antenna world replacement was a simple swap for the old busted one.

    Birdman
     
  4. robertgarven

    robertgarven F1 Rookie
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    Friends,

    Here is a couple of pictures:

    1. The antenna the car came with (not original) notice the 2 whit wires with red lines these are the power wires.

    2. The switch from my gt4 . notice the 3 wires the 2 white with red stripe go yo th antenna, the gray one is 12v and goes to the battery. It is not grounded.

    3. The section of the WM pertaining to the radio. notice that my switch is correct. it also shows the antenna grounded.

    When I push my switch up power runs down the white wire, when I pus it down it runs down the other wire. The antenna I got from antenna world has 2 wires, it works when you apply power to one wire and the the other wire grounded. With the antenna connected to the 2 factory wires I tried unsuccesfully to get it to ground using all of its metal parts to the chassis.

    A couple of side notes:
    *one guy at a radio store I talked to said the only way I could get the antenna to work with my switch is to rig up a set of relays.
    *This is funny as whenn I got the car it had a bag of relays and wiring balled up and tie wrapped to the antenna picture above. Since the antenna never worked I discarded the relays thinking it was some kind of modification and that I would get an original antenna later.
    * The S-41 from antenna world came with a switch and wiring harness that the instructions said needed to be grounded, it had 6 wires going to it and since i need the original switch I did not use it.
    * The antenna had no ground strap of any kind such as the photo that Dave sent and I tried to jury rig up several but they did not work????
     
  5. robertgarven

    robertgarven F1 Rookie
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  6. robertgarven

    robertgarven F1 Rookie
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  7. robertgarven

    robertgarven F1 Rookie
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    Here is Dave's antenna; note the ground strap, my car did not have one and even when I attempted to ground the unit as in the pic no luck:
     
  8. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Rob G. -- I emailed you some info regarding the "relay"-type solution -- did you receive it OK?
     
  9. Birdman

    Birdman F1 Veteran

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    Robert,
    Have you pulled and looked at the antenna switch in your dash to find out what kind of switch it is (i.e. how many poles/throws?) It's likely that your switch can be rewired to the original configuration and run this antenna. To my knowledge, the original Ferrari antennas used the same wiring configuration that the replacement one from antennaworld uses (two wires that swap polarity to raise/lower). If your switch is original then you can rewire it properly. If you can't rewire it, I would venture to guess that the switch isn't original anyway, and you should just substitute the switch that came with the new antenna and forget a mess of relays, which is just more crap to go wrong.

    Birdman
     
  10. Birdman

    Birdman F1 Veteran

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    Oops, I forgot. Your switch should be a double pole, double throw, meaning that there will be 6 terminals on the switch. If it has this, we can rewire it to the original.

    It sounds like someone replaced the antenna in your car with a different kind, and then rewired the switch accomodate it.

    Birdman
     
  11. robertgarven

    robertgarven F1 Rookie
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    Birdman,

    I am sure the switch is original, see the pics and diagram above. Steve M. (thanks) just sent me a diagram on how to rig up the relays, like he must have done on his car. I will post it when I get home

    2 questions:

    What kind of antenna was in this car originally?

    Why can somepeople do the swap with no problem, I am guessing some of the cars had a later switch? I dont have a schematic for the QV so I cannot say???

    Rob
     
  12. dave80gtsi

    dave80gtsi Formula 3
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    The original radio aerial switch can be 'tricked' into working with a modern two-wire electric aerial by simply wiring a diode across one set of the switch's terminals.

    Easy to do, it'll cost you a dollar for the diodes at a Radio Shack.

    I did this one last month - personally, I wouldn't mess about with a relay as the diode fix is way simpler!

    If anyone is interested in the specifics, let me know.

    Cheers - DM
     
  13. f355spider

    f355spider F1 World Champ
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    Rob,
    Dave80gtsi just reminded me that some folks modify their wiring, adding the diode to make a "fully automatic" antenna, work with a switch in the "semi-automatic" mode. Look at the antenna you have...it is an "automatic", which may mean "fully automatic". It may be worth investigating the rest of your wiring...someone may have added a diode.

    In other words, your wiring may not be in it's original configuration...

    Just a thought.
     
  14. Steve Magnusson

    Steve Magnusson F1 World Champ
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    dave80gtsi -- I'm interested (and guess I'm daft because I don't see how just adding diodes anywhere to the always "+" stock SPDT switch network side would every put a ground signal on one of the motor wires so there must be more connections than your words indicate) -- please post your "diode" solution schematic (because I agree that the relay solution is somewhat cumbersome ;)).
     
  15. f355spider

    f355spider F1 World Champ
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    Steve,
    I'll try and find it...I got a copy from another person on F-chat. It was from an article in Prancing Horse several years ago...

    I also have a diagram somewhere from a car stereo repair shop, showing how to add a diode to convert to semi-automatic operation...

    Need to do some digging.

    Found them! Okay the Prancing Horse article shows how to REWIRE a fully automatic antenna into semi-automatic operation; requires soldering skills. The other one is just adding the diode.

    I don't have a scanner...Steve how about I fax to you, and you could post or diagram it for others?

    I'll ping you for a fax number....
     
  16. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Dave H. -- you can FAX me at 303-417-7575 (but I think you're talking about a different issue).
     
  17. LP400S

    LP400S Formula 3

    May 18, 2002
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    I would love to see the solution on converting the Hirschmann auto antenna to semi auto. Please post :).
     
  18. f355spider

    f355spider F1 World Champ
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    Rob,
    I did a "google" search, the Hirschman antenna that was previously installed, is a fully automatic antenna. Your existing wiring has probably been modified in some way to get the antenna to work in a semi-automatic mode with your existing switch.

    It is also possible that the existing antenna was modified internally to work with your exisiting wiring...not sure.

    But look at this manual for your (old) antenna, it is supposed to be activated by a "trigger wire" from a radio...not by a switch.
    ftp://ftp.hirschmann.de/pub/montage/m921008001.pdf

    If your wiring was modified, that would explain why the replacement antenna is not working by just hooking up the two wires.
     
  19. robertgarven

    robertgarven F1 Rookie
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    Dave and all,

    The hirshman was the one that was in my car when I bought it I unhooked the antenna and relays and recently replaced it with the S-41 like yours. I am positive that my existing switch is original, check out the picture and diagram above. I am trying to track down an original antenna, if not will probably have to rig up the relay thing. I am interested in the diode fix also, but what I think is lacking in the original set-up is the grounding of the switch.

    Rob
     
  20. f355spider

    f355spider F1 World Champ
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    Rob,
    I also believe your switch is original...I am just wondering if the wiring was modified at all...

    Is there someone with a GT4 that can verify the outputs of the two wire where they terminate in the trunk?
     
  21. joeyy

    joeyy Karting

    Nov 11, 2003
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    Rob

    i had the same problem. Dave H was kind enough to send me a link to antenna world and i too bought a s-41 and had the same problem that you are having.

    the fix for me was easy since i had what was left of the original antenna i refit the mast of the s-41 into the factory antenna body. the origial antenna is an AUTOVOX. while making the change i learned that the original is a very different animal than anything i have seen aftermarket. it has a very heavy duty motor that has its own ground so it can be powered directly thru the switch. it also has a seperate set of windings that are soldered to the "down" wire which reverses the polarity so the motor can run backwards. the s-41 is rather rinky dink next to the original so i am wondering if a temporary fix may burn something out?

    let me know if this helps you in any way. if you need pics i can take the antenna out post them.
     
  22. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Dave H. -- Got the FAX OK, but we are talking about different things. I took Rob G.'s original message to mean that he wanted to manually control a simple aerial motor that needs reverse polarity applied directly the motor winding to reverse motor direction using the stock 308 SPDT switch -- I believe this is only possible via the relay solution.

    The case described in your FAX is for using the stock 308 SPDT switch and a diode to send the proper combinations of the 2 input signals to a specific, more-advanced aerial motor in such a way that it works properly with the stock 308 SPDT switch (i.e., the 2 input signals to the motor in this case are not direct connections to the motor winding). I'd agree 100% that if Rob G. has that same particular more-advanced aerial motor he should pursue the diode solution rather than the relay solution -- sorry for the confusion.
     
  23. robertgarven

    robertgarven F1 Rookie
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    Joey,

    Thank goodness! I knew the original must have been a different animal. If you can post some pictures I would be greatful! I am glad to know that I was not the only one with this problem! I am even less experienced with electronics than mechanics so I am a you guys mercy with this one.
     
  24. f355spider

    f355spider F1 World Champ
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    Steve,
    He already has (had) the more advanced fully automatic antenna installed in his car....that's why I think that Rob may have the diode installed somewhere in his wiring already. Now he is trying to install the regular semi-auto antenna, and it will not work.

    But based on Joeyy's post, maybe I got this all wrong, and the early cars are wired differently than the later cars...but if so..how did the previous owner ever get that Hirschman antenna to work...if it ever did work?
     
  25. dave80gtsi

    dave80gtsi Formula 3
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    Here's the step-by-step information which will allow you to use your original up/down radio aerial console switch with an inexpensive modern replacement aftermarket fully automatic aerial motor. I did this installation several months ago and can personally vouch that it works a treat.

    Modern aerials have two (2) wires leading to the motor, plus a ground. Aerial wire 'A' is connected directly to the battery and is intended to see 12 V ALL of the time, even when the ignition is switched off. Wire 'B' is switched 12 V via a trigger terminal on the backside of modern radios - You turn the radio on, and 12 V is then applied to wire 'B', which fully extends the aerial until an end-of-travel limit stop is engaged. Remove the trigger signal from wire 'B' (i.e., you turn off the modern radio), and then wire 'A' fully retracts the aerial, again until end-of-travel is reached.

    To use this modern aerial with your old OEM console switch, attach wire 'B' to the "down" side of your console switch. Attach wire 'A' to the "up" side of the console switch, and then wire a pair of diodes across terminals 'up' and 'down' of the switch. The diodes that I used were Radio Shack model 276-1141, 3 amp 50 V peak, which come two for $0.99 USD. I used both diodes in the package wired in parallel simply to offer a safety factor against failure of one of them alone. Arrange the diodes so that current can flow from "up" to "down", but not "down" to "up".

    Now, when you move the console switch to "down", only wire "A" sees 12 V and the antenna retracts, since the diode prevents any current from travelling to wire 'B'. With the switch in the center "off" position, there is no current to either "A" or "B" and the antenna is stationary. Move the switch to "up", and both wires 'A' and 'B' see 12 V and the antenna extends.

    Thus, the original switch now works just as Enzo intended!

    It's really quite straightforward if you sketch it all out on a piece of paper, but if anyone has any questions let me know. (For that matter, I'd also appreciate hearing from anyone who successfully uses this technique!)

    Cheers - DM / Ohio
     

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