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Powering my Ham Radio

Beta V

Author, Dad, Mentor, Technology Critic
Nov 8, 2017
170
49
Redmond, WA USA
I'm installing a Ham radio transmitter in my Model X and wanted to know what's the best way to power it. I understand there is a 12VDC power source in the frunk, but don't know how to access it, nor do I know how to get the wires into the main cabin. Is there a safe way to cross the "firewall?" I haven't bought the radio yet but I'm looking at one that will put out 50 watts or more (perhaps as high as 100 watts). I understand the console-mounted 12VDC cigarette outlet has its current limited so it might not be the best choice when transmitting on full power.

I'm mounting the antenna on either the lid or on the spoiler and using a base-loaded Diamond Antenna K400CNMO mounted on a Diamond RR-72BNMO. It's short enough so as not to interfere with the garage door or hit low-hanging fixtures in other parking garages. I'm open to suggestions there too.
 

Silicon Desert

Active Member
Oct 1, 2018
3,392
3,158
Sparks Nevada / GF 1
You bring up a good curiosity question for me. What is the maximum amount of current that can be drawn from the "cigarette lighter" outlet in a Tesla? I only know that in every ICE car I have ever had, I was able to use one of those DC to AC inverters to power different types of camping accessories and a CB radio with a linear amplifier that drew at least 100 Watts (about 8 amps DC).
 

DCGOO

Active Member
Nov 24, 2015
1,530
900
Indianapolis, IN
I'm installing a Ham radio transmitter in my Model X and wanted to know what's the best way to power it. I understand there is a 12VDC power source in the frunk, but don't know how to access it, nor do I know how to get the wires into the main cabin. Is there a safe way to cross the "firewall?" I haven't bought the radio yet but I'm looking at one that will put out 50 watts or more (perhaps as high as 100 watts). I understand the console-mounted 12VDC cigarette outlet has its current limited so it might not be the best choice when transmitting on full power.

I'm mounting the antenna on either the lid or on the spoiler and using a base-loaded Diamond Antenna K400CNMO mounted on a Diamond RR-72BNMO. It's short enough so as not to interfere with the garage door or hit low-hanging fixtures in other parking garages. I'm open to suggestions there too.

Best way to power is to use the 20 amp circuit for the brake controller. Tesla even provides a pigtail to connect to it. It is a pain to find the mating connector, but basically it is a loose connector above the OBDII access. That circuit is unswitched (always on). The aux power connectors are only good for 10 amps, and are switched. Not adequate for a 50 watt mobile.

The antenna is tricky. First, mag mounts are out because of the all aluminum body. Plus there is no surface that is adequately flat to mount anything on. What I ended up using is a trunk lip mount near the top of the hatch. An antenna of any length, will run into interference with the FWD. So I ended up using one of those short stubby dual band antennas. The antenna really sucks, but it does get a signal out better than a handheld inside the car. I had to mess with the maximum open setting of the hatch to avoid interfering with the FWD. Be careful though, the FWD does not always follow the same path for opening and closing. The antenna is a severe compromise, but I carry a 19 inch whip that I can change to should I need decent antenna performance.

I mounted a TM-V71A with the control head in the cubby, RF deck in the back, under the deck in my 5 passenger. Speaker and microphone in the center under the arm rest. I guess I should send some pix.
 

TechVP

Active Poster
Nov 12, 2016
400
286
Corvallis, OR
100% Agree with @DCGOO.
I attached the Power Brake pigtail, added inline fuses (prob not necc. but preventative anyway) heat shrunk the assembly and it terminates to a PowerPole connector. I added mine right after delivery 3/2017.

I have operated an Icom ID-5100, Icom 706MkIIG, RemoteRig and [believe it or not] a Arlo Netgear wireless camera setup on this buss with no issues at all. The last 3 at the same time... the ID-5100 was switched out to accommodate the latter gear.

The folks at the Service Center turned their head like a confused puppy when they first saw the power line running from where the Power Brake controller plugs in. Bunch of guys scratching their beards. Got a chuckle from them.

I added a Larson 2m/70cm window mount antenna to the right rear 3rd panel window. And it works. I don't use it as often as I thought... but it does work.
As for the HF Rig, I operated my QTH remotely via RemoteRig on a long NV trip. That was fun.

There was a thread started by a model S owner that got several responses 2 years ago... I will post it if I can locate it.

Bottom line, go ahead. If you are ok with the antenna mounting and don't mind the paint blemishes... I have had good luck with my setup. While everybody else is running generators... you'll have the best, most reliable setup for Field Day! Huge battery ;-)

PS: There is another, not well documented, location to tap. It is near the passenger footwell under the carpet. Apparently there is another fuse box location in there. As I recall, however, I don't believe it offers as much current, and may also be switched to turn off with the X. If you are interested I have a tech bulletin around here somewhere that I can PM.

-TechVP
 

TechVP

Active Poster
Nov 12, 2016
400
286
Corvallis, OR

Beta V

Author, Dad, Mentor, Technology Critic
Nov 8, 2017
170
49
Redmond, WA USA
I spent a couple of hours trying to find an ideal location for the antenna. I tried to use the top of the rear hatch and was about to pat myself on the back when I decided to test it. When I opened the gull-wing door, it hit the antenna. I had to disassemble it to get the door to closed. Moving it further back on the hatch seemed like a good idea and it worked until both the hatch and gull-wing were opened at the same time--as we do at the airport. Not good. I started over. After considerable trial-and-error (with my wife hovering at my shoulder), there just wasn't an ideal place on the hatch that gave me the ground plane I wanted under the antenna, and be out of the way when loading the car.

My final plan was to mount the bracket on the frunk lid. There was plenty of clearance and the antenna cable length was no longer a factor. See the picture that shows where it's mounted. Antenna Picture 2.jpg And when the frunk is open, the antenna does not hit anything due to the design of the hinge.

So, my only remaining problem is where to route the antenna cable? Is there a way to get inside the passenger compartment from inside the frunk? I expect this problem will repeat itself when I have to find the aforementioned brake battery wires. I looked in the frunk and I didn't see any way to access the innards.Antenna Picture 1.jpg

Upon further research, I understand there is 12VDC available just above the OnBoardDiagnostic port inside the firewall. That's great. I'll look for it there. I also found this (long and detailed) discussion of getting to the grommets that would let me route the antenna cable into the cabin.

Grommets In Firewall (Useful for Installations)

Thanks for the help.
 
Last edited:

dland007

New Member
Mar 4, 2020
1
0
Columbus, IN
@Beta V - which antenna is this? Mounting location I can live with on my '16 Model S. Have you had good luck with this across the bands on HF?

Thanks - Dave

I spent a couple of hours trying to find an ideal location for the antenna. I tried to use the top of the rear hatch and was about to pat myself on the back when I decided to test it. When I opened the gull-wing door, it hit the antenna. I had to disassemble it to get the door to closed. Moving it further back on the hatch seemed like a good idea and it worked until both the hatch and gull-wing were opened at the same time--as we do at the airport. Not good. I started over. After considerable trial-and-error (with my wife hovering at my shoulder), there just wasn't an ideal place on the hatch that gave me the ground plane I wanted under the antenna, and be out of the way when loading the car.

My final plan was to mount the bracket on the frunk lid. There was plenty of clearance and the antenna cable length was no longer a factor. See the picture that shows where it's mounted.View attachment 400335 And when the frunk is open, the antenna does not hit anything due to the design of the hinge.

So, my only remaining problem is where to route the antenna cable? Is there a way to get inside the passenger compartment from inside the frunk? I expect this problem will repeat itself when I have to find the aforementioned brake battery wires. I looked in the frunk and I didn't see any way to access the innards.View attachment 400332

Upon further research, I understand there is 12VDC available just above the OnBoardDiagnostic port inside the firewall. That's great. I'll look for it there. I also found this (long and detailed) discussion of getting to the grommets that would let me route the antenna cable into the cabin.

Grommets In Firewall (Useful for Installations)

Thanks for the help.
 

Beta V

Author, Dad, Mentor, Technology Critic
Nov 8, 2017
170
49
Redmond, WA USA
I have subsequently changed antennas and opted for a Larsen NMO2/70B dual-band antenna. No, it's VHF/UHF but I have friends that have installed a tri-band antenna on that same base mount. Warning: take it off if you go through a car-wash.

I have subsequently remounted the radio control head (I have a Yaesu FT-400) on the dash under the steering wheel using ProClip and Lido mounts. I found the suction-cup mounts just didn't work in cold weather.
IMG_5500.jpg
 

SteveQLQ

Member
Sep 14, 2019
10
2
Boynton Beach, Florida
Beta V. Excellent post! This gives me something to do while waiting out the Coronavirus (besides sitting around drinking Corona!).
I have an FT7900 I pulled out of my IC before trading up to a 2019 S.
Do you have any more photos of your install, especially power source, wire routing, and antenna mount (it looks like one I already have).

Thanks and 73, Steve (N2QLQ)
 

SteveQLQ

Member
Sep 14, 2019
10
2
Boynton Beach, Florida
Beta V...excellent post, Thank you! I want to put my FT7900 in my 2019 S. This should give me something to do while waiting out the Coronavirus besides sitting around drinking Corona!

How has your rig been working? Do you have any more pictures showing cable routing, power supply, etc. I know there will be differences between the S and X, but it would be a good guide.

Thanks, and 73 Steve N2QLQ
 

Beta V

Author, Dad, Mentor, Technology Critic
Nov 8, 2017
170
49
Redmond, WA USA
Beta V. Excellent post! This gives me something to do while waiting out the Coronavirus (besides sitting around drinking Corona!).
I have an FT7900 I pulled out of my IC before trading up to a 2019 S.
Do you have any more photos of your install, especially power source, wire routing, and antenna mount (it looks like one I already have).

Thanks and 73, Steve (N2QLQ)

The radio itself is "taped" to the carpet on the side of the hump in the front right seat. The power wire is snaked behind from there to the brake-controller 12VDC source. It's located behind the carpet just under the dash (against the far left outer wall). The antenna wire was snaked in by a pro who made it look simple. In my Model X (many are different), there was a large rain-gutter-sized channel that led through the firewall on the left side of the frunk compartment under the windshield. That lead to the doorframe where I snaked the antenna cable down and to the radio. I added a third-party microphone extension cable and now keep the mic in the console. I also had to keep the data cable plugged in as it's hard to dismount the double-sided-sticky-tape attachment.
 

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