Antenna switch install.

E28 technical advice asked and given! Troubleshooting, modifications and more.
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Antenna switch install.

Post by demetk »

Got bored one day and up on my todo list was an antenna cutoff switch because for the most part the headunit is mostly in CD or AUX input mode and the antenna gets pretty grimy when it's always up when the radio turns on. I know some headunits have an antenna cutoff built-in which powers up the antenna only when AM/FM inputs are selected. None of my middle of the road headunits have that feature.

The easiest solution would have been to interrupt the white wire at the radio with a toggle switch but that would look too hack, even for me. Then I thought of a fog light switch. Although that would do the job and look almost oem, a window switch suddenly caught my eye and I started to like the up/down arrows on each button. Push the "Up" arrow and the antenna extends, push the "Down" arrow and the antenna retracts. Cool, so a window switch it would be.

But how would I control the antenna with the momentary contacts of the window switch? I thought, build a circuit. Great, I need some paper, lots of it. After lots of paper, here’s what I came up with. The components used are 2 DPDT mini relays, one window switch and a little bit of thin gauge wire.

The circuit,

Image

The top relay turns on via a momentary push of the UP button on the window switch. Once the top relay turns on, the bottom relay supplies continuous power to the top relay’s coil so it stays latched on until the DOWN button is pushed on the window switch or until the ignition is turned off.

A miniature relay that I used. You need two of them.

Image

The window switch terminals that I used,

Image

Wired and installed.

Image

If anyone has read this far and needs more info just let me know.

Cheers.
Last edited by demetk on Jun 15, 2018 3:57 PM, edited 1 time in total.
Blue Shadow
Posts: 9291
Joined: Feb 12, 2006 1:00 PM
Location: SE PA

Re: Antenna switch install.

Post by Blue Shadow »

Nice work.

I used the double button fog light switch with the other button powering the fan in the trunk for amp cooling.

I use the non-lighted window switch on the other side of the radio to control the door lock unlock.
Coldswede
Posts: 6858
Joined: Oct 10, 2008 1:48 PM
Location: Back U.P. North,. Where the water's blue, the wind is free and seasons four.

Re: Antenna switch install.

Post by Coldswede »

Oh now this is a great, classy mod! I'm gonna steal it 3x's!

Great job

:bow:
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Antenna switch install.

Post by demetk »

Blue Shadow wrote:I use the non-lighted window switch on the other side of the radio to control the door lock unlock.
This is a great mod and it is on my todo list.
foamy
Posts: 1524
Joined: May 29, 2007 6:39 PM
Location: North Branford Connecticut

Re: Antenna switch install.

Post by foamy »

i used a spare fog light switch i think it was. one push puts it up one push brings it down. also if i leave it on the antenna will come up and go down when i start and turn the car off.
waynet1
Posts: 2524
Joined: Jan 10, 2011 12:49 PM
Location: Port Charlotte,FL-Newport,RI

Re: Antenna switch install.

Post by waynet1 »

foamy wrote: also if i leave it on the antenna will come up and go down when i start and turn the car off.
Why would anyone want such a thing to happen ? :dunno:
foamy
Posts: 1524
Joined: May 29, 2007 6:39 PM
Location: North Branford Connecticut

Re: Antenna switch install.

Post by foamy »

so if you forget the switch on it will still go down when the car is shut off and no one will walk by and feel jealous that my antenna works and breaks it off.
Owndapwn
Posts: 486
Joined: May 18, 2014 12:22 PM
Location: Kansas City, MO

Re: Antenna switch install.

Post by Owndapwn »

The design is simple and offers little room for error.
Kudos on actually writing a proper electrical diagram. I'd add it to the back of my manual if I were you.
Das_Prachtstrasse
Posts: 5562
Joined: Sep 10, 2006 7:06 AM
Location: Melbourne, Doooown Under

Re: Antenna switch install.

Post by Das_Prachtstrasse »

Fantastic. I've got an e23 HVAC switch (on off style) that fits in the dash blank I've been meaning to wire into the antennae for a while. If that fails ill use your method. The one second from the right with the two arrows and green backlight.

Image
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Antenna switch install.

Post by demetk »

Thanks for the kind words.

This mod is ideally suited in the situation where you do all of the maintenance on the e28 but others primarily drive it and therefore want to implement Best Antenna Use Practices or BAUP for you acronym junkies. If I had used a regular switch to control the antenna I would always be reminding people to use the antenna only when listening to the radio. With this window switch mod I don't have to remind them. Now it's up to them to make the effort. Want the radio, push the Up button or else listen to static.

My wife asked me if I'm going to install this mod on the other cars, which are e34s, so that everything remains consistent. I said "No I'm not." And she said "Why not, don't you want consistency?" I said "Obviously I want consistency, but there is no reason to install the same switch in the e34s because the e28 is the only car with an actual antenna." :)

cheers
Blue Shadow
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Joined: Feb 12, 2006 1:00 PM
Location: SE PA

Re: Antenna switch install.

Post by Blue Shadow »

relay source? not digikey or mouser unless it is a big order.
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Antenna switch install.

Post by demetk »

These guys were nice, http://www.allelectronics.com/make-a-st ... lay/1.html

I bought 5 of RLY-497 @ $2.50 but that one is no longer available. The one I linked above will work and is cheaper.

Buy a bunch because once you master switching with relays you may never stop.
Owndapwn
Posts: 486
Joined: May 18, 2014 12:22 PM
Location: Kansas City, MO

Re: Antenna switch install.

Post by Owndapwn »

A lot of times, the head unit will control that.
On mine, which is just some cheap head, when you switch the input to radio, the antenna comes up. Switch it back to TRS, it goes back down.
Blue Shadow
Posts: 9291
Joined: Feb 12, 2006 1:00 PM
Location: SE PA

Re: Antenna switch install.

Post by Blue Shadow »

Owndapwn wrote:A lot of times, the head unit will control that.
On mine, which is just some cheap head, when you switch the input to radio, the antenna comes up. Switch it back to TRS, it goes back down.
You got new technology. We roll with vintage, period correct and back then the HU only had power to the antenna circuit to tell the antenna to go up, switched off with unit off and antenna comes down. The next version, with a bigger chip, allowed them to design a circuit to signal the antenna only when needed and cut the signal when the other inputs are used.

Vintage rules...lets us have to design, build and install new stuff in our cars.
528elover
Posts: 656
Joined: Sep 18, 2010 11:14 PM
Location: Tucson, Arizona

Re: Antenna switch install.

Post by 528elover »

Blue Shadow wrote:Nice work.

...

I use the non-lighted window switch on the other side of the radio to control the door lock unlock.
That's an amazing modification. Would you mind sharing how you did this? This is one thing these cars don't, but should, have - a central locking button. I was thinking about getting a switch from a later model BMW or a Mercedes for this mod. Please share if you'd be willing. Thanks in advance!
Blue Shadow
Posts: 9291
Joined: Feb 12, 2006 1:00 PM
Location: SE PA

Re: Antenna switch install.

Post by Blue Shadow »

528elover wrote: This is one thing these cars don't, but should, have - a central locking button.

Actually we do have it. It is built into the Driver's door lock. Operate it and the rest of the car follows, lock or unlock. The front passenger has some control, too, I think but not complete.

I'll need to hunt it down, but the idea is to supply switching to a couple pins on the CLCU.

Well that wasn't too hard to find. Check out the different projects listed here including the button

http://www.lexam.net/peter/carnut/framelift.html
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Antenna switch install.

Post by demetk »

Blue Shadow wrote:Well that wasn't too hard to find. Check out the different projects listed here including the button

http://www.lexam.net/peter/carnut/framelift.html
Thanks for the link.

Hey he's using the same pins on the window switch that I am. These switches are sure handy.
Speeddragon
Posts: 2
Joined: Jun 15, 2018 3:04 PM

Re: Antenna switch install.

Post by Speeddragon »

demetk, could you please re-upload the images, found thumbnails on google but I am not good enough with electronics to reverse engineer the blurry image haha.
Really love this mod.
demetk
Posts: 8212
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Location: CT, USA

Re: Antenna switch install.

Post by demetk »

and done.
jhh925
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Location: San Francisco Bay Area

Re: Antenna switch install.

Post by jhh925 »

Saw your posting title. Thought to myself, "Oh, I'll bet I know what this post is about."

Started reading ... sure enough:
Got bored one day and up on my todo list was an antenna cutoff switch because for the most part the headunit is mostly in CD or AUX input mode and the antenna gets pretty grimy when it's always up when the radio turns on. I know some headunits have an antenna cutoff built-in which powers up the antenna only when AM/FM inputs are selected. None of my middle of the road headunits have that feature.
I was pretty excited 'cause I'd been irked about the same issue and a few weeks ago, I did the same thing! But then I got to this part:
The easiest solution would have been to interrupt the white wire at the radio with a toggle switch but that would look too hack, even for me.
Doh!

Image
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Antenna switch install.

Post by demetk »

LOL. Pretty sure I wasn't meaning you when I wrote that. :)
RonW
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Joined: Feb 12, 2006 1:00 PM
Location: Long Island, NY

Re: Antenna switch install.

Post by RonW »

I think you can make a momentary antenna switch with a single relay with a built-in series diode, like the low beam relay. The diode allows current to flow from pin 86 to 85 (actuating the relay), but not vice versa.

I haven't tested this, so caveat emptor.
  1. Connect the white wire from the radio to pin 30 of the relay and pin 3 of the switch.
  2. Connect pins 86 and 87 of the relay to each other, to pin 1 of the switch, and to the antenna.
  3. Connect pin 85 of the relay to pin 8 of the switch.
  4. Connect pin 5 of the switch to ground.
The switch is not illuminated unless there's power on the white wire from the radio, so if the switch lights are off, the switch won't raise the antenna.
Speeddragon
Posts: 2
Joined: Jun 15, 2018 3:04 PM

Re: Antenna switch install.

Post by Speeddragon »

@RonW, I don't know enough from relays to confirm it.


@demetk,

Thanks, and I think I Understand how the scheme works, just need to buy the relais and stuff.

I think these will be sufficient:

https://nl.aliexpress.com/item/5Pcs-lot ... autifyAB=0
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Antenna switch install.

Post by demetk »

^ Those relays look to be the same ones and are much cheaper than what I linked.
demetk
Posts: 8212
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Antenna switch install.

Post by demetk »

RonW wrote:I think you can make a momentary antenna switch with a single relay with a built-in series diode, like the low beam relay. The diode allows current to flow from pin 86 to 85 (actuating the relay), but not vice versa.

I haven't tested this, so caveat emptor.
  1. Connect the white wire from the radio to pin 30 of the relay and pin 3 of the switch.
  2. Connect pins 86 and 87 of the relay to each other, to pin 1 of the switch, and to the antenna.
  3. Connect pin 85 of the relay to pin 8 of the switch.
  4. Connect pin 5 of the switch to ground.
The switch is not illuminated unless there's power on the white wire from the radio, so if the switch lights are off, the switch won't raise the antenna.
Interesting concept if it works. Now prove it Ron. ;)
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