Midland MXT275 Noise

[WSEB581]

I just installed an MXT275 in my Ford truck.

Initially had terrible engine whining, so I re-wired the power supply directly to the battery and that seems to have solved that issue.

Now I have a terrible "raspy" sounding static when receiving/transmitting. I've tried the 3db Ghost antenna as well as the 6db whip. It does seem to be worse when the truck is moving (i.e. increased engine speed).

Antenna mount is clamped to the hood of the truck. This is an aluminum body truck, could that be the problem? Any ideas would be much appreciated 

[Socalgmrs]

Don’t know if that’s the problem but you are using 2 ground plane antennas with no ground plane.  So right off the bat you’ve got issues.   Then about 90% of the people I know that had a midland dumped it in the first few months and spent less money on a much better radio because of problems like this.  With that aside you may try one of the many differ Types of filters on the positive side. Maybe even both sides of the power wires.   I’ve been installing cb, ham, gmrs and car audio systems for well over 20years and ive never had this problem in an old or new car or truck if run directly to the battery.  Are you using the coax and antenna that comes in the 275 kit? Might be part of the issue  

 

[WRYZ926]

You could be getting noise from several sources. The obvious one is the alternator. But it really could be anything. I had an occasional whine on my radios in a 2023 Ford Escape until I put clamp on ferrite beads on both ends of the cable going from the alternator and the battery. I also put ferrite beads on the positive and negative wires going to the radios.

Make sure that the negative wire from the radio goes to a good chassis ground and not the negative terminal of the battery. And if putting clamp on ferrite beads on the power cables does not work then add some to the coax cable. One can also add a grounding strap directly to the alternator and a near by chassis ground too.

PS: it's not going to really matter what brand of radio or brand of antenna one uses, modern vehicles with all of their electronics and computers are noisy. Hybrid and all electric vehicles are worse and why vehicle manufacturers are trying to get rid of AM radios.

 

[WSEB581]

Thank you both for the replies.

One question, I know the antenna needs a ground plane. It was my understanding that any METAL surface would work as a ground plane. Is the Aluminum hood not sufficient?

[SteveShannon]

9 minutes ago, WSEB581 said:

Thank you both for the replies.

One question, I know the antenna needs a ground plane. It was my understanding that any METAL surface would work as a ground plane. Is the Aluminum hood not sufficient?

An aluminum hood is fine. I think maybe wrxp381 thought that your antenna mount doesn’t couple to the hood somehow. without knowing more about the mount you’re using I can’t tell, but most do. 
Keep in mind that the position of the antenna on a ground plane affects the propagation of the signal. 

[WRXB215]

Aluminum is fine for a ground plane. It's the lip mount that may be problem. If that is how you are going to keep the antenna mounted, you may want to try an antenna that doesn't need a ground plane.

@SteveShannon beat me to the punch but I'm posting anyway. 

[dosw]

A ground plane is more than just having the antenna mounted against a metal surface. It needs to be 1/4 wavelength radius (6.5 inches) or more, in all directions. It doesn't have to be electrically connected or grounded, just needs to be a fairly flat surface for the 6.5" radius (or more).

 

A lip mount works for me because there's a flat metal panel aft of the hood, too. But if you're at the edge of the hood without a flat metal surface on the other side from the mount your propagation will be stunted in the direction of inadequate ground plane.

 

But if you experience this issue at, say, 200 feet, it's less likely to be a ground plane issue. I'd still be looking for sources of electrical interference.

[WSEB581]

Let me add to the puzzle.

I switch to the westher band, the automated voice comes across with no interference, but whenever the automated voice is talking it's got the same raspy effect. Similar to how a speaker would sound if it was blown.

 

[WRXB215]

19 minutes ago, WSEB581 said:

the same raspy effect. Similar to how a speaker would sound if it was blown.

I suppose the speaker itself could be part of the problem. You never know.

[SteveShannon]

5 minutes ago, WRXB215 said:

I suppose the speaker itself could be part of the problem. You never know.

I agree; it sounds like you have a radio problem, not RFI or antenna. 

[Hoppyjr]

I shared this in a different thread about the same exact model radio, but here’s some info that may help -

We installed the same model, current production version with the USB-C port, into a Jeep JK. Antenna was also properly grounded.

We experienced the same issue: heavy static, virtually no range (maybe a block or two at best), yet the weather channels were clear. We could hear some traffic, including configured repeater channels, but transmit was a no-go. There was static on receive too.

I contacted Midland customer service via their website. While a quick web search will explain that the older models of this radio (without USB-C) had issues with repeater channels, it’s not widely known that even the most recent USB-C version has a firmware issue. I don’t know if it’s just a bad production run, but I suspect that’s the case.

Midland advised me to send it in and they would update the firmware, but wouldn’t even cover the shipping to them. Since I was within the Amazon return period I elected to return the radio. We installed the higher power MTX575 that was previously in my 4Runner, and it works great.

To do it again, I’d go with a different brand radio altogether.

I hope this helps.

Hoppy

[WSEB581]

Thank you for the info. Checking my amazing return window now

[WRYZ926]

2 hours ago, Hoppyjr said:

To do it again, I’d go with a different brand radio altogether.

That's how I feel about the MTX-500 I had and my brother felt the same way about the MTX-575. Neither one of us own a Midland radio anymore.

One can update the firmware on the MTX500 if they want. But the MTX-575 is just like the MTX-275, you have to ship them both back to Midland for any firmware upgrades.