Infotainment RFI on VHF/UHF Ham Radio

Muley · June 12, 2019

I recently installed a VHF/UHF dual-band (2m/70cm) ham radio, Yaesu FTM-7250D. in my 2016 Silverado and have determined that the infotainment system is causing quite a bit of noise in the 70cm (440 MHz) range. It's definitely coming in though the antenna as it stops when I unscrew the antenna from its NMO mount or unplug the antenna coax at the radio. The noise stops when the infotainment system is off or if I pull the infotainment system fuse while it's on.

Has anybody else here had a similar problem and how did you solve it (if you did)?

Edited June 12, 2019 by Muley

LtGMC · June 16, 2019

I just installed my Icom ID5100 and haven't noticed any RFI so far. I read some wheres someone else having some issues but can't remember if it's on this forum, Radio Reference forum or another forum.

How do you have the radio powered and where is your antenna etc installed? The up-fitter guide from GM recommends routing the power wires in front of the engine and the antenna installed behind the B pillars.

tuckerm · June 17, 2019

I have a 2014 and just installed a vehicle repeater for my public safety radios. The public safety radios operate on VHF and the vehicle repeater is on UHF. I, too, have been fighting this problem. I have noticed degraded VHF performance from day one and now that I installed the UHF repeater I have noise up and down the UHF repeater channel. It is not there when the truck is off and the MyLink stuff is off.

My truck has power wires from the console to the battery direct. Antennas are coming down both sides of the truck in the rear pillars. The scanners I have in there also suffer the same hit. Any thoughts?

LtGMC · June 18, 2019

22 hours ago, tuckerm said:

I have a 2014 and just installed a vehicle repeater for my public safety radios. The public safety radios operate on VHF and the vehicle repeater is on UHF. I, too, have been fighting this problem. I have noticed degraded VHF performance from day one and now that I installed the UHF repeater I have noise up and down the UHF repeater channel. It is not there when the truck is off and the MyLink stuff is off.

My truck has power wires from the console to the battery direct. Antennas are coming down both sides of the truck in the rear pillars. The scanners I have in there also suffer the same hit. Any thoughts?

I'll double check mine. I don't think I turned on the My Link radio the night I test drove it after installing radios.

Have any pictures of your radio and antenna set up? How did you run the power wires?

tuckerm · June 18, 2019

It's not just the radio, it's the whole MyLink system. Radio, Touchscreen, etc. I tested my repeater at 450, 463, and 470mhz and the noise is there across all those frequencies.

You can see my install here of the radios and antennas. The antennas are covered in salt in this album, they're a little cleaner in the summer months.

Link: https://imgur.com/a/kAk9M

LtGMC · June 18, 2019

I've seen those pictures on another forum.

Very professional and nice looking install BTW!

Looks like you have 1 antenna mounted towards the front of the cab. Try unscrewing the coax from the radio on that one and see if it makes any difference.

.........

Just checked mine and I don't have any RFI on the UHF 440 band. Tried it with the squelch off, the truck running, with the truck off and with the MY Link system on and off. It made no difference.

FWIW

I went by the up-fitter guide and ran the power wire in front of the radiator to the driver's side. I put both antennas behind the B Pillar and centered on the roof. One antenna is a quarter wave VHF for the fire dept and the other one is a dual band VHF / UHF for the amateur radio. The antennas are about 18 inches apart. I ran the coax for the antennas down the passenger side C pillar and tried to keep them away from the side curtain airbag as much as possible.

I also used 6 gauge zip wire to an after market small fuse block. The radios are powered from the fuse block and their ground wires are connected to the same 6 gauge ground wire.

Edited June 18, 2019 by LtGMC

Muley · June 18, 2019

After considerable investigation and experimentation, the only thing I've found that mitigated the 70cm band noise was relocating the antenna now mounted on a front fender bracket away from line-of-sight with the infotainment system which I determined using a mag mount antenna that quieted the radio when it was on the cab roof. Unfortunately, I can't put the antenna on the roof as I want to park in my garage and a rooftop antenna won't allow that.

Interestingly, if I attach either of my two handheld Alinco dual-band transceivers to the fender-mount antenna they don't pick up the noise nor does my Yaesu FT-857D that I use mostly for portable operation. Apparently those radios have better front-end noise rejection.

I called Yaesu tech. support about the problem but they had no suggestions that I hadn't already tried.

I guess the only remaining thing is to investigate whether the truck's infotainment system can be shielded or choked to eliminate or minimize the noise.

HeySkippyDog · June 20, 2019

I have CB in mine, I'm not getting much RFI from the truck at all.

Mag antenna on the roof, power is supplied from my center jumpseat armrest cubby by a cigarette plug adapter. I snapped an RF choke on the power line to keep it clean, but I really don't think it needs it.

Oddly enough if I plug in to the center stack outlet just below the touchscreen unit, my RX drops about 30%, choke or no choke.

Where are you getting your power from in the truck? Location seems to matter, and from what you're saying, would make sense that the infotainment system is noisy.

Sent from my SAMSUNG-SM-J727A using Tapatalk

HeySkippyDog · June 20, 2019

I think you'd have better luck shielding your radio from the external noise than trying to suppress RFI in the cab. Try some ferrite on your power cable, keep adding cores or get a big one and keep winding the cord through it until your noise issue is solved. I like using the snap-on ferrites, and then I cover them collectively in a piece of heat shrink and shrink it as far as it'll go, then zip-tie the ends of the shrink to the power cable.

Sent from my SAMSUNG-SM-J727A using Tapatalk