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Power antenna electrics


TomoHawk

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E-

So it sounds like you need a singe-throw (SPST) switch that stays in the up or down setting? So either it's up or it's NOT up with the new ones.

The OEM switch is a Single Pole - Double Throw. One wire, two possible connection points. Additionally, it is a Momentay SPDT, which basically means that it spring centers itself to the Center Off position.

The circuit changes I noted above were to be able to make a FULLY Automatic Antenna work with the OEM wiring. This has been referred to as "fooling" the antenna. However, there is a mistake in there and I apologize for not having found it sooner.

Once I went back to re-examine the wiring of the antenna we "fooled", I realized that the OEM Switch will NOT do this job.

You MUST use a DPDT. Ideally, a Momentary Center Off is best.

The changes due to the correct Switch wiring are as follows:

UP (Top 2 connections) = Blue/Red Blue/White - 2 wires going TO Antenna

Center OFF (Mid 2) = Blue shunted to Blue - Same Power wire from Dash to BOTH center connections

BOTTOM (Low 2) = Blue/Red wire shunt from Top Left. Nothing on Right

At the Antenna, the Blue/Red is used for the Continuous 12v + connection (usually RED), and the Blue/White is used for the Power-ON sensor connection (usually BLUE). The Antenna is further connected to ground via either it's case or a separate wire.

In operation, when the switch is in the UP position, 12V+ is fed to BOTH the antenna's RED and BLUE wire, connecting it as if the radio had been turned on...the internal relay will allow the antenna to raise as long as you hold the switch in positon. When you release, all power is disconnected and the antenna is frozen in position.

When you slide the switch to the DOWN position, now only the RED wire receives power, and the BLUE does not, which mimics the power situation when a radio equipped to use a Full Auto Antenna is powered off, this causes the internal relay of the antenna to power the motor to bring the antenna down. Again, it retracts as long as you keep the switch in the down position, freezing when you release.

Typically, the antenna spool will also have limit contacts that will disconnect the power in either the UP or DOWN circuitry at it's most extreme points of travel.

This means that if you were unable to get a MOMENTARY Center Off DPDT switch, the antenna SHOULD disconnect at the extreme TOP and BOTTOM of travel.

But having goofed once, I'll admit that I've not tested this part out. I've been lucky to find DPDT Center OFF switches.

FWIW

E

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Ask the place you buy it at.

In my experience with CB's, you have to tune the antenna and/or tune the radio to the antenna...at a fixed length.

An electric antenna would have variable height, don't know how you would tune the CB radio to work with it, but that's the whole point. My experience is 20+ years ago, so best ask the dealer or distribuitor.

E

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the only thing an auto antenna has that a semi auto doesnt is a timer/limit circuit(the auto antenna cuts off when it hist fully opend or fully closed, the Semi automatic runs until you let loose for the switch(no built in end of travel recognition) If you can find the limit switch/circuit, you can modify it.

Will

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The semi- auto ones have a clutch-type thing that will slip if the cable is fully in or the mast is fully out. It is a must, or every antenna out there would have been broken. There's no need for any limiters then. Hopefully, you will let off the UP/Down switch before it is fully out or in.

I would expect that there is a clutch in the automatic antennas too, for the same reason.

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Thanks, Enrique

I found that Harada makes a semi-automatic unit (SX-11) that should be fine, except the only difference is the look of the antenna stub that's exposed above the fender, and it uses a 2-wire power system, so you need to use a fancy cross-wired switch to control it. If I can't get one locally or through eBay (like this one: http://cgi.ebay.com/Harada-SX-11-Semi-Automatic-POWER-ANTENNA-KIT_W0QQitemZ260052096274QQihZ016QQcategoryZ6755QQssPageNameZWDVWQQrdZ1QQcmdZViewItem)

then I'll have to modify an automatic one (sounds kike fun :squareeye )

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I was out shopping for a semi-automatic antenna, and at one store, the tech guy actually argued with me that there's NO SUCH THING as a semi- automatic antenna, and there's NO WAY you can rewire a fully-automatic unit to work with something like the OEM S30 antenna switch. the guy kept showing me the bullet connectors and explained (again & again) that "This one gets CONSTANT POWER, and this one gets SWITCHED power, and that's the ONLY way you can wire the antenna.

I asked the tech is the unit uses a DC motor. He said Yes (so fare, OK.) I asked if there was a clutch inside (No, there are limit switches on the toothed belt inside.) The guy did not know what the little black thing on the mast was for, so I summized it was a kind of timer-relay thing to run the motor up or down.

So I will be either getting a semi-auto unit, and wiring up a DPDT relay so the antenna works like the oem one, or the cheapest fully-auto one, and wiring it the same, after I look into the black mystery-box on there.

Either way, I'm going to tackle this (easy?) item before moving on to the next item on my Winter to-do list.

thx

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I was out at the car, and took the old antenna. I found out that the power connector on the antenna will plug into the switch connector under the dash, so if you want to fit a switch, you can get the connector off an oem antenna unit.

So I just need to get a switch. What would you think about this one:

Mercedes Benz W126 300 420 560 ANTENNA SWITCH

thx

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