circuit for power antenna

Greetings to all.  I am a car hobbyist with a dilemma.

I am adding a modern aftermarket power antenna into my 1968 Firebird.  This antenna is the generic aftermarket style with a 12v constant power lead and a 12v signalling lead, and a ground to chassis.  Since the car has an AM radio and the antenna will rarely need to be raised, so I'd like to make the antenna controllable.  The factory radio does not have that capability, and aftermarket SPST switches look out of place.

I can use a factory power top switch, which mounts under the dash and looks like it belongs, to move the antenna; however this is a momentary SPDT switch so it won't stay up, it goes up then back down when I release the button.

Here is what I would like to happen:

Car off, antenna down.  Car on, antenna down, until button is pressed, then antenna goes up.  Antenna stays up until one of two things happen:  button is pressed or car is shut off, then antenna goes down.

Since this is outside of the knowledge I currently have, if anyone can help me solve this problem I would greatly appreciate it.

How confident are you in your ability to remove the radio, remove the cover and take some photos of the back end of the shaft that houses the power switch? There may not be a wire on your radio for your purpose. There is a suitable wire inside the radio. When you turn the radio on, we just need to find the wire that powers the radio.

When taking the photos, you may need to use a real digital camera, and set it to MACRO mode, the setting with the flower on it. This allows you to take extreme close up photos that are actually in focus.

I see where you are going with this, and I wish I'd thought of it before the car was assembled. Since I built the car, I am sure this is within my abilities; however, removing the radio at this point would require major disassembly.

Hi,
If you forgo the antenna lowering when you switch the car off, you can easily wire the top switch to the antenna. This will require a 6A diode also though.
Have your switch connected to its power source...fuse box usually. should have two output leads..up and down, purple and grey?
Connect the up lead of the switch to the signalling lead and also the non-banded side of the diode.
Connect the down lead of the switch to the constant power and the banded side of the diode.
Ground the antenna.
When you operate the switch up, antenna will go up...stopping if you release the switch before it cycles up all the way. Operating the switch to down will lower the antenna. You've just turned a fully- automatic antenna to a semi-automatic one.
Mark

A Firebird friend suggested the following, feedback appreciated.

Relay 1, 30 to ACC +12V, 85 to ground, 86 to momentary switch up, 87 to relay 2 pin 30.

Relay 2, 30 to Relay 1 87, 85 to ground, 86 to momentary switch down, 87a to antenna signal.

Forgot the obvious, switch common to ACC 12v, antenna power to BAT 12v (to complete the retract cycle with key off)

I missed something somewhere.  It goes up, but only if I hold the button, and goes down when I release it, exactly as if I was using only the momentary switch.

hi,
your wiring is incorrect, and you still need a diode.
relay 1 (down): 86 down switch, 85 ground, 30 accessory power, 87a
        to relay 2 30, 87 not used.
relay 2 (up): 86 up switch & banded side of diode, 85 ground, 30 from
        relay 1 87a, 87 trigger lead of antenna & non-banded side of
        diode, 87a not used.
the diode can be a 1N4001 or equivalent. the diode performs the latch (set) function by taking the up relay output and connecting back to its coil. the unlatch (reset) is performed by the down relay, or the disconnect of power.
mark