Aerial wiring?

[iani]

I fitted a new electric aerial today, unfortunately it didn't come with a switch and it is designed to raise when it receives a signal from the radio. I have a 60's radio installed however and this doesn't have an aerial feed, I therefore need to use a switch. The aerial has 3 wires, one Earth, one permanent 12v & one for an aerial feed from the radio. I jury rigged a 12v supply and when I connected this to both the 12v supply wire and the aerial feed wire the aerial went up, if I remove the aerial feed wire it doesn't retract however. I'm looking for advice as to what kind of switch I should get to be able to raise and lower this aerial, any thoughts?

Ian

[alistair260661]

u need to switch the radio off before disconnecting the wires - and it should go down

[iani]

u need to switch the radio off before disconnecting the wires - and it should go down

I don't have a radio sensing wire Alistair so that functionality isn't available, I need to use a switch instead, my question is what type of switch should I be looking at?

[Stagsongas]

Maybe you need to treat the 2 wires (other than earth) both as +12V, one for power up, and the other for power down. Making DC motors run in reverse is often done by reversing polarity.

Good Luck

Steve

[iani]

Thanks Steve, I have an On/Off/On switch coming, I think you might well be right here.

Ian

Maybe you need to treat the 2 wires (other than earth) both as +12V, one for power up, and the other for power down. Making DC motors run in reverse is often done by reversing polarity.

Good Luck

Steve

[stag8manod]

Hi Ian, My suggestion would be an electric window rocker switch with the fused permanent feed to the aerial and wiring the other two across the switch so that it operates the same as in the window application. It would also only operate when depressed in the direction you need and matches what's fitted already.
Cheers Ian A

[iani]

Thanks Ian, this isn't actually in a Stag though, I bought the aerial for my Stag and never got round to fitting it, I have installed this in my Series 2 E-Type so there is no matching switch available, I need to use a toggle as that will fit the hole that the previous switch used. I'm thinking that I should use an On/Off/On switch with a 12v supply to both On terminals and the aerial sensing wire only going to the "up" ON terminal, I'm just looking for a sanity check from the forum brain :-)

Ian

Hi Ian, My suggestion would be an electric window rocker switch with the fused permanent feed to the aerial and wiring the other two across the switch so that it operates the same as in the window application. It would also only operate when depressed in the direction you need and matches what's fitted already.
Cheers Ian A

[Stagsongas]

Ian,

Just to clarify what I wrote, some motors can be reversed by changing the polarity, but others may be double wound, giving one +12V for up, and the other for down with the earth unchanged.

Given that your aerial has a permanent earth, it is less likely it works on pole reversal, but that earth may just be provided for the receiving part of the aerial (if not earthed to the body at the mounting).

So, it still could be that the remaining pair are meant to be pole reversed, + and - for up and - and + for down. It might take some experimentation, just take care not to let the smoke out ,

Whatever, given that you have 3 wires it's very likely that your idea of an 'On - Off - On' switch will do the trick, the hard part will be getting the radio head to run it automatically if you don't have the sensing wire (used to be yellow on many sets from dark and distant memory).

Good Luck

Steve

[pagan]

For the sensing wire (yellow on car radio) the can be only 4 conditions ie +12v or GRD 0V or left floating or a resistance to earth.

What is known is
12volt to power.
GRD to earth.
sensing wire unknown

The sensing wire if connected to 12v then the aerial goes up.
What you could try is....
1 disconnect the sensing wire, (not earth it, just leave it floating) and see if the aerial goes down.
2 connect it to earth and see if the aerial goes down.
3 If there is a resistance to earth needed, you could try a variable potentiometer to earth, then wind the pot back and forth to find the resistances for the different states.
Once you know the condition of the sensing wire, then you'll can work out what kind of or condition to wire a switch.

just touch the sensing wire to either power or ground or not either, then make your hard connections.

Allan

Personally, I can't see variable 3 needed.

[Bob Heritage]

I seem to remember soldering an extra wire to the on/off switch many moons ago on a Radiomobile that I had at the time.

[Stagsongas]

If all else fails, it can be done with changeover relay. Pin 87 for +12V to send the mast up when radio is turned on, and the opposing/alternative pin 87a to give +12V on the second wire to retract the mast when the radio is turned off.

That's if the Aerial really does have 2 x 12V requirments (up and down) and there's no yellow wire on the set of course.

[davidf]

As far as I know, one lead should have 12v constant, the other lead should have 12v all the time you want the aerial up, and 0v when you want the aerial down. So, the switch should just be a normal on/off switch on one lead.

Or, for example, you could connect an ignition switch feed to the sensing lead, so the aerial is up all the time the ignition is on.

[Mike Stevens]

As DavidF said, but probably with a changeover switch which connects either +12V to the control wire (aerial up) or 0V (aerial down). Since modern radios only have the 1 wire to control the aerial, I can't see it being anything else!

Cheers,
Mike.

[iani]

Thanks chaps, I can now raise and lower the aerial by touching both wires (up) removing the sensor wire and briefly reconnecting it (lowers) I'm going to try fitting a momentary switch and see if that works.

Ian

[iani]

In the end the fix was a lot easier than expected:

12v ignition controlled supply to aerial red wire
Earth wire connected
12v ignition controlled supply to aerial blue wire (radio sensing wire) via a simple ON/OFF switch

I can now raise or lower my switch as desired, thanks for the assistance chaps.

Ian