GMRS Radio Question

[prerunner1982]

@Kballs a dashcam or more so the power supply can cause RFI. I have seen it on 2m (VHF) so it could be possible on GMRS (UHF). Did you try unplugging the dashcam power cable from the vehicle to see if it fixed the issue?

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[Dougstdig]

Not ideal, but will work for monitoring both radios.

…that is once I finish the wiring and routing of the coax?

 

[Dougstdig]

Tuned to just over 55 watts
CB channels added

 

[Radio Guy]

Tuned to just over 55 watts
CB channels added

I have a Striker SR-94HP I bough on a whim and although it puts out lots of power and works well, its a total PIA to use while mobile. You only have one knob for everything and have to push the menu button then choose what you want the one knob to do. If you need to adjust the volume or get in a noisy area and need to adjust the squelch its not a simple thing to do trying to see the tiny menu while keeping the wandering vehicle on the road.

I also found the transmit audio a little bland and had to upgrade the mic to a preamp type. And on high power the radio gets real hot if you transmit much.

 

[Dougstdig]

When I took a break from the big truck I gave my tuned Galaxy DX 98 VHP to a good buddy of mine. Still have my 29 in reserve. I tinkered with the 94HP a bit in my previous vehicle and became pretty proficient at navigating the menus by touch. Granted, I had a solid external speaker in that application, which I don’t think I’ll be using due to space constraints.

I’ll be mounting it here…up close…. The gmrs will be mounted on a Rugged Radios mount on the passenger side center console.

 

[Josh00333]

I had interface with that wiring set up as well.

I ran a dedicated ground and took power off the hot aux lead, not the ignitionhot lead and it cleared it perfectly.

mine was some sort of power/grounding issue between the ignition hot and that ground post.

Thank you everyone for your responses and willingness to help me sort this out. Just to troubleshoot, I hooked the MXT115 stock antenna up and popped it on my hood, running the wire away from all other possible interference sources. Still getting a random signal.

I have the radio wired into the passenger’s side AUX bundle and grounded just behind the glove box. Something interesting, when I was installing the radio it powered up with out a ground wire connected to the radio (grounded via the antenna). Definitely threw me off.

Yes, I believe it does. However, the signal I am receiving is a constant interference.

 

[Radio Guy]

When I took a break from the big truck I gave my tuned Galaxy DX 98 VHP to a good buddy of mine. Still have my 29 in reserve. I tinkered with the 94HP a bit in my previous vehicle and became pretty proficient at navigating the menus by touch. Granted, I had a solid external speaker in that application, which I don’t think I’ll be using due to space constraints.

I’ll be mounting it here…up close…. The gmrs will be mounted on a Rugged Radios mount on the passenger side center console.

I have two radios in my JT now and put two speakers stuck to the ceiling above and behind the drivers seat using super heavy duty claw type velcro. The speakers are small rectangular units about 4X2X2" and left over from older Motorola cell phone adapters.

I find the speakers mounted right behind my head make it easier to hear the radios and it doesn't bother passengers (wifee) as much as something centrally mounted and turned up louder.

 

[Kballs]

@Kballs a dashcam or more so the power supply can cause RFI. I have seen it on 2m (VHF), so it could be possible on GMRS (UHF). Did you try unplugging the dashcam power cable from the vehicle to see if it fixed the issue?

I am giving this a go today. The camera installed isn't a dash camera; it's a front generic "trail camera" that Tazer sells. This camera's power and video cable is run with the antenna wire through the dash and firewall.

I'm beginning to think this is where my issue is...

 

[Dougstdig]

Many of our electronics come with these on them. I purchased assorted sizes, but have not had a chance to test as of yet. My CB had a bad throttle wine in my other vehicle. I’ll post an outcome when I have a chance to finish my install.

 

[Radio Guy]

Many of our electronics come with these on them. I purchased assorted sizes, but have not had a chance to test as of yet. My CB had a bad throttle wine in my other vehicle. I’ll post an outcome when I have a chance to finish my install.

A single ferrite bead does nothing for RFI on cables you need enough in series to get well over 500 ohms choking impedance and preferably over 1,000 ohms or higher. At VHF or UHF three snap on types of a #43 mix will usually make a noticeable difference or two to three winds of cable through a single bead will also work.

For interference on CB or lower frequencies you need a larger ferrite where you can wrap many turns around it and the ferrite mix will need to be maybe #61 for CB and #31 for general HF use.

 

[Kballs]

Well, I have some significant issues. Any suggestions given the readings below?

Ch 1 - reading 462.563 - 6.74w - Trans% 75.27 - SWR 2.97
Ch 21 - reading 462.700 - 10.45w - Trans% 75.44 - SWR 2.96

 

[Radio Guy]

Well, I have some significant issues. Any suggestions given the readings below?

Ch 1 - reading 462.563 - 6.74w - Trans% 75.27 - SWR 2.97
Ch 21 - reading 462.700 - 10.45w - Trans% 75.44 - SWR 2.96

What kind of antenna? Try channels 8 through 14, they should be in the 467MHz range. If the match is worse there then the antenna is too long, if its better then it could be too short. If there is little or no change between the 462 and 467 channels then it could be lack of ground plane or cable/connector issues or the antenna is down below the hood and snuggled up too close to the tall edge of the hood.

 

[Dougstdig]

A single ferrite bead does nothing for RFI on cables you need enough in series to get well over 500 ohms choking impedance and preferably over 1,000 ohms or higher. At VHF or UHF three snap on types of a #43 mix will usually make a noticeable difference or two to three winds of cable through a single bead will also work.

For interference on CB or lower frequencies you need a larger ferrite where you can wrap many turns around it and the ferrite mix will need to be maybe #61 for CB and #31 for general HF use.

Thanks for the heads up??

I’ll allow for plenty of wire before trimming and making it Purdy. I got the multi pack for like 20 bucks or something. Granted, my power cable is 10ga, I should be able to get several wraps per need. Then again I’ll stay positive and maybe it will be fine and I won’t need any.

 

[Dougstdig]

Well, I have some significant issues. Any suggestions given the readings below?

Ch 1 - reading 462.563 - 6.74w - Trans% 75.27 - SWR 2.97
Ch 21 - reading 462.700 - 10.45w - Trans% 75.44 - SWR 2.96

Did you cut the coax down to size? I’m not sure about VHF, but pre made coax usually comes in increments of 3 ft…with the most common being 18’. I’ve seen SWR’s get way out of wack when folks cut it to size (to fit) or coil it up to stash it somewhere.

 

[Kballs]

What kind of antenna? Try channels 8 through 14, they should be in the 467MHz range. If the match is worse there then the antenna is too long, if its better then it could be too short. If there is little or no change between the 462 and 467 channels then it could be lack of ground plane or cable/connector issues or the antenna is down below the hood and snuggled up too close to the tall edge of the hood.

The antenna installed is a Midland MXTA25 3dB Gain Ghost Antenna.

Could a positive and negative wire run alongside the antenna wire cause this much of an issue?

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