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Modern power antenna on original up down antenna switch

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Instructions on how to install a new inexpensive power antenna to work with the OEM antenna up/down switch.

When I purchased my 1972 Fairlady Z-L it only had the 8-track face plate and a loose antenna switch. The 8-track unit itself was missing. I purchased an old 8 track off ebay, 3d printed some parts to build a mock up unit. It does not play but cartridges can be inserted, the buttons work and it looks original. The up/down switch is secured and functional.

I am in the process of putting in a secret audio head unit so that I have a radio and use Bluetooth. I wanted to replace the manual antenna with a power antenna. However new antennas operate differently.

Original antenna uses two wires, power one and the unit goes up, power the other and the unit goes down.

New antennas operate like this;
up - power to both red and green wires
down - power to red wire only. (however I discovered that the antenna needs a pulse to both wires first to turn it on.)

I achieved this with the use of three bosch type relays, a capacitor (1000 microfarad) and resistor (10k Ohm) to provide a pulse to the green wire.

The capacitor/resistor powers the third relay for about 0.5 Seconds

Relay 1 and 2 for up ensure that the circuits are isolated from the down wiring. Relay 3 provides the pulse to green for down. 

 

Installed 8-track.jpg

240z Power Antenna on original switch.jpg

Relay Set for Antenna.jpg

Installed Relay Set.jpg

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The other advantage to this circuit (compared to others I have seen) is that it does not require any additional 12v supply. Makes installation simple with no wiring changes / additions needed. 

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Cool, my antenna switch in my 71 240z isn't working. Or the motor has failed. Not sure which yet. This is a good solution, but I want to retain the original parts.

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I have struck the same problem. The old antenna had seized with the plastic wand inside the telescopic tubing detached rendering the unit unrepairable. So I bought a new 'modern' one which looked almost identical but couldn't get it to operate in both directions via the factory switch no doubt for the very reason you describe.

Your solution is well planned and executed but way over the head of this non-electrickery person!

 

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