innertwist

iTrader: (3)

Got sick and tired of the antenne puncturing holes in the car cover and plain old forgeting to extend my 5' aerial, so here was my solution. I picked up the antenne off a 94 Regal from the junkyard ($10). Sure, an aftermarket power antenna can be had for as little as $30 and would probably be an easier install, but at least I can rest assured that this one will last for a while. GM antennes have cutoff switches for when the antenna reaches the extents of its' travel which prevents damage to the motor and gear. Anyway, here it is as I grabbed it from the junkyard:



I was considering welding a mounting bracket in place for it, but I opted to zip tie it instead. I cut the drain tube shorter and fed it out a pre-existing hole behind the bumper. I didn't bother with the ground strap and hence removed it. Here it is before wiring:



I sourced the rubber bushing at the top from a different car, an 88 or thereabouts. A lot of the GMs around those years used the same bushing.



The wiring for the GM antenna is a bit different from the stock rx-7 wiring. The GM uses a 3 wire system and the rx a 2 wire system. For the stock RX-7 wiring the flow of current to the motor just reverses between up and down, of course with no protection for when the antenna reaches it's stopping point. For the motor connection of the GM antenna, power is applied to one pair of pins depending on whether it is going up or down. Internally, two of the wires to the motor are connected through the extent switches and the third wire goes directly to the motor. One way to interface the motor to the RX-7 wiring is to connect one lead to the lead which directly connects to the motor internally and use a relay to switch the other rx lead to the appropriate switched wire. This is exactly what I did. So that the relay doesn't trip in both up and down directions, a diode is used in the powering of the relay. Since it was there already, I used the relay the antenna came with. This will also save me the trouble of digging it out of the garage on that distant day I install a better head unit that has an auto-antenna pin. So here's my power adapter (at long last):


(I didn't splice the motor wires just in case I do want to plug it into the relay one day)

The gender of the antenna signal connector is also backwards, so I made a gender mender. (yeah, the wire off the antenna could have just been cut with a new connector soldered)



That's it. The button on my console now has a function. Since I alluded to it earlier, here's the function of the relay as well as the rest of my wiring notes:

RX-7 connector
(blue/red is the spade closest to the clip)
blue/red +, blue/yellow - on up
blue/red -, blue/yellow + on down

GM Antenna
Switches off power to motor when fully extended/retracted (3 wire)

motor connection
pin 4 is labelled C and has a white wire
pin 5 is labelled B and has a green wire
pin 6 is labelled A and has a gray wire

without relay connection:
UP: B+, A-
DOWN: C+, B-

for relay connection:
pin 1 (black): -
pin 2 (green): relay switch
pin 3 (orange): +
antenna goes up when pin 2 is pulled high, down otherwise

dominicaneddy

looks like I am on the hunt for a GM antenna
Thanks! and good job on the details,
How long or how much time was involved? so others like my self can know and what to expect?

innertwist

iTrader: (3)

The first thing I should have mentioned is that I have an SA. Looking at this article it appears that FBs have different wiring for the antenna. With the 3 wire system described in that article the wiring would be a direct match for the motor connection, forgoing the relay. Of course you wouldn't have the ignition off down function that that implementation provides if you wire it directly to the motor.

There are better ways to do this, in all respects. My car didn't come with, and I have never come across, the OE antenna. If I did have one, I almost certainly would have adapted the mounting bracket. Not to say that the zip ties aren't secure, they are, but this mounting method depends ALOT on the geometry of the antenna. I spend over an hour repositioning it, trying different spots to tie down to, and rotating the rubber (it's angled) before I got it just right. Not all the GM antennes have the same dimensions, so unless you get the exact same one, you're going to have to play some with the mounting.

I also wanted to do the least rewiring possible for my antenna. If I were to implement the ignition off down function like the aformentioned article, I would have had to run my own possitive lead to the rear of the car (SA's don't have a hatch light). The wiring for me was a matter of expedience. I was more excited about having a working power antenna than changing the stock configuration. Now I realize that it gets rather annoying having to remember to retract the antenna when I turn off the car (there's not much I can due for the auto up with the stock head unit without hacking it).

But, if you really wanted to do it this way, it shouldn't take very long. If you take the shorcuts of splicing the motor wire (rather than building a male connector for it like I did) and directly fitting a new RF connector on the antenna, the wiring should be fairly quick. If the antenna you get is exactly the same, you have the picture to go by. Otherwise, expect some time for fitment. Remember to pick up the connector for the antenna relay if you're going to use it (the input side, a spare motor side too if you don't cut the motor wire - they're keyed) and an extra male RF connector (or two if you're going to make a gender adaptor) while you're at the junkyard. Also, antennes that are fully retracted are the ones that are most likely to still work - this might just take you the longest out of any of it.