Issue with through hole NMO mount in vehicle.

[WRTZ361]

I have been using a magnetic NMO mount on my vehicle for about 6 months. I did not like the cord showing so I decided to install a through hole mount in my roof since people are saying it is just overall better to mount this way. I installed it as according to the instructions and when I went to turn the radio on, it would not receive anything. My radio is capable of receiving the NOAA radio channels and I was planning on tuning into the strongest one for my area before I attempted to transmit. I assumed that if I did not set up the antenna correctly. I would damage my radio if I tried to transmit. The interesting part of this is that when I turned the vehicle off, the radio began receiving the NOAA channel very clearly for the 3 seconds it takes for it to turn off. I have no idea what this means. I believe I assembled everything correctly and I checked all of the connections at the radio itself. Any suggestions would be appreciated. 

[SteveShannon]

2 hours ago, WRTZ361 said:

I have been using a magnetic NMO mount on my vehicle for about 6 months. I did not like the cord showing so I decided to install a through hole mount in my roof since people are saying it is just overall better to mount this way. I installed it as according to the instructions and when I went to turn the radio on, it would not receive anything. My radio is capable of receiving the NOAA radio channels and I was planning on tuning into the strongest one for my area before I attempted to transmit. I assumed that if I did not set up the antenna correctly. I would damage my radio if I tried to transmit. The interesting part of this is that when I turned the vehicle off, the radio began receiving the NOAA channel very clearly for the 3 seconds it takes for it to turn off. I have no idea what this means. I believe I assembled everything correctly and I checked all of the connections at the radio itself. Any suggestions would be appreciated. 

Unscrew the pl259 on the radio end and slide it partially out so the center conductor is still connected but the shield is not. See if that makes any difference. 
Do you have a multimeter? Or better yet an antenna analyzer?

[WRTZ361]

3 hours ago, SteveShannon said:

Unscrew the pl259 on the radio end and slide it partially out so the center conductor is still connected but the shield is not. See if that makes any difference. 
Do you have a multimeter? Or better yet an antenna analyzer?

I will try that, by only leaving the center connected what am I testing for? I do have a multimeter. I don't know what an antenna analyzer is. 

[SteveShannon]

4 hours ago, WRTZ361 said:

I will try that, by only leaving the center connected what am I testing for? I do have a multimeter. I don't know what an antenna analyzer is. 

You’re checking for a damaged cable or something at one end or the other that might be shorting the center conductor to the shield.  It’s just a guess on my part, but maybe when you turn off your radioa relay opens up and for the next three seconds, while voltage is draining from capacitors in the power circuits that’s why it suddenly works on NOAA channels.

With your multimeter you might put it on the continuity test and check to see what the resistance is between the center conductor and the shield with the NMO antenna removed.  It should be very large, like in the megohms or “OL” as some meters say. If it’s a low value, there might be a short between the center conductor and the shield of the coax.  That could happen at either end due to a poorly installed connector or damaged cable. 

An antenna analyzer is a tool some of us have that performs test on the feedline and antenna to help understand what’s happening.  Don’t run out and buy one unless the bug bites you and you decide to go from GMRS into ham radio. Then, heaven help you because you’ll never stop shopping for radios and test gear (or building them yourself!)

[nokones]

Ask Steve stated, with the multi-meter, you want to check and see if you have continuity from the center pin of the PL259 connector to the center contact of the NMO mount. Your reading should be "zero". If you have any reading than there is resistance and that may mean and open circuit thus a defective cable or connector issue. Then at either end of the cable, connect the meter to the center pin of the PL259 and to the outside metal portion of the PL259 pin exits the connector that is attached to the cable, not the loose doo-hickey that tightens the cable to the back of the radio SO239 connector; and you should have a reading of "OL". If you get a reading of "zero", you have a direct short more likely at the connector or at the NMO mount also meaning a defective cable. I vote for a short at the connector.

What NMO mount and cable are you using? If you are using something bought from a discount big warehouse third-party type reseller that doesn't specializes in only radio electronics like DX Engineering or Arc Antenna, send it back and get a refund or scrap it and buy a real cable from a reputable radio electronics or antenna reseller that specializes in the subject products. Anything other than that is just pure junk.

[WRTZ361]

4 hours ago, SteveShannon said:

You’re checking for a damaged cable or something at one end or the other that might be shorting the center conductor to the shield.  It’s just a guess on my part, but maybe when you turn off your radioa relay opens up and for the next three seconds, while voltage is draining from capacitors in the power circuits that’s why it suddenly works on NOAA channels.

With your multimeter you might put it on the continuity test and check to see what the resistance is between the center conductor and the shield with the NMO antenna removed.  It should be very large, like in the megohms or “OL” as some meters say. If it’s a low value, there might be a short between the center conductor and the shield of the coax.  That could happen at either end due to a poorly installed connector or damaged cable. 

An antenna analyzer is a tool some of us have that performs test on the feedline and antenna to help understand what’s happening.  Don’t run out and buy one unless the bug bites you and you decide to go from GMRS into ham radio. Then, heaven help you because you’ll never stop shopping for radios and test gear (or building them yourself!)

I went out to my car this morning and turned my car on. Turned on the radio and it just worked. I changed nothing since trying it last night and it just started receiving. There is a small amount of noise coming in with the transmission, but still less noise than my HT at that same location. If I grab the coax cable with my hand. the noise diminishes. the tighter I grab it, the less noise there is. Now I might have been stupid for doing this, but I wrapped the extra coax in a nice clean coil. I am self diagnosing this as poor shielding, and my body is acting like a ground for it. Let me know if I am wrong in that thinking. I am trying to learn as much as I can about these systems. 

I have already been bitten by the small bug of collecting HT radios. This is my first foray into anything more intricate than that. I am completely self taught with people like you guys helping me along. 

 

 

[WRTZ361]

1 hour ago, nokones said:

Ask Steve stated, with the multi-meter, you want to check and see if you have continuity from the center pin of the PL259 connector to the center contact of the NMO mount. Your reading should be "zero". If you have any reading than there is resistance and that may mean and open circuit thus a defective cable or connector issue. Then at either end of the cable, connect the meter to the center pin of the PL259 and to the outside metal portion of the PL259 pin exits the connector that is attached to the cable, not the loose doo-hickey that tightens the cable to the back of the radio SO239 connector; and you should have a reading of "OL". If you get a reading of "zero", you have a direct short more likely at the connector or at the NMO mount also meaning a defective cable. I vote for a short at the connector.

What NMO mount and cable are you using? If you are using something bought from a discount big warehouse third-party type reseller that doesn't specializes in only radio electronics like DX Engineering or Arc Antenna, send it back and get a refund or scrap it and buy a real cable from a reputable radio electronics or antenna reseller that specializes in the subject products. Anything other than that is just pure junk.

I know I can't recognize quality just by reading the brand name. Mostly I bought based on reviews of people that gave reasons as to why they liked or hated it. I will try and be as detailed about what I have and then you guys can tell me what to replace or do differently. 

Antenna: Melowave stealth 1/4 wave GMRS nmo mount

Cable & Mount: Midland MXTA24 low profile NMO mount

Radio unit: KG 1000-G Plus

[SteveShannon]

12 minutes ago, WRTZ361 said:

I know I can't recognize quality just by reading the brand name. Mostly I bought based on reviews of people that gave reasons as to why they liked or hated it. I will try and be as detailed about what I have and then you guys can tell me what to replace or do differently. 

Antenna: Melowave stealth 1/4 wave GMRS nmo mount

Cable & Mount: Midland MXTA24 low profile NMO mount

Radio unit: KG 1000-G Plus

I don’t see anything there that makes me cringe.  The radio is as good of a GMRS certified radio as you can get.  The Midland mount is okay.  It’s nice to install because it only requires a 3/8” hole. It might not be “commercial radio” quality like a police car or ambulance would get, but it should be fine.  If it fails then ask one of the guys like Kenny what NMO mount they use in a public safety vehicle where price is no object and reliability is the only concern.  
The Melowave antenna is not one I’m familiar with, but I have seen them sold on one of the buy two way radios websites.  There’s no reason to doubt it, but as far as I know it’s strictly GMRS.

[WRYZ926]

@WRTZ361, I have a few questions for you

Did you have the noise issue when using the magnetic mount?

How is the radio power leads connected?

 

Having the excess coax coiled normally won't cause any issues/interference.

From your first post, it sounds like you are getting interference from the vehicle electric system. Some clamp on ferret beads on the cable connecting the alternator to the battery will help as will making sure the alternator is properly grounded. Also use some copal on ferrite beads on the power connection of the radio.

You can also put 1 or 2 clamp on ferrite beads on the coax where it attaches to the radio to see if that helps.

I have no experience with the Melowave antennas but you are using a good NMO mount and radio.

The reason I mentioned putting clamp on ferrite beads on the cables/wires, is that it can and will help eliminate RFI and EMI issues. I was occasionally getting some noise when I would transmit while my 2023 Ford Escape was running. This was with my Wouxun KG-1000G and TYT TH-7800 radios. I'm using Midland NMO mag mounts. adding ferrite beads to the cables helped. I still get occasional noise but it is way less than before. 

 

[WRTZ361]

29 minutes ago, WRYZ926 said:

@WRTZ361, I have a few questions for you

Did you have the noise issue when using the magnetic mount?

How is the radio power leads connected?

 

Having the excess coax coiled normally won't cause any issues/interference.

From your first post, it sounds like you are getting interference from the vehicle electric system. Some clamp on ferret beads on the cable connecting the alternator to the battery will help as will making sure the alternator is properly grounded. Also use some copal on ferrite beads on the power connection of the radio.

You can also put 1 or 2 clamp on ferrite beads on the coax where it attaches to the radio to see if that helps.

I have no experience with the Melowave antennas but you are using a good NMO mount and radio.

The reason I mentioned putting clamp on ferrite beads on the cables/wires, is that it can and will help eliminate RFI and EMI issues. I was occasionally getting some noise when I would transmit while my 2023 Ford Escape was running. This was with my Wouxun KG-1000G and TYT TH-7800 radios. I'm using Midland NMO mag mounts. adding ferrite beads to the cables helped. I still get occasional noise but it is way less than before. 

 

I had very minimal noise when I was running the magnetic mount. If it helps at all I have everything installed on 2015 jeep cherokee. The only thing I can say surprised me about the performance of the radio system when it was mag mounted is the range seemed short. My Wouxun UV9GX HT got just as much reception as the mobile system. That could be due to the 1/4 wave antenna though. On a side note, it seems the best performance for GMRS comes from using a 1/2 wave antenna. Just haven't had anyone verify that it is an upgrade worth doing. 

The power leads came with the radio, with the positive being fused. I wired the radio to my remote switch panel, which is then feed through a voltage protection module which will automatically cut "accessory" systems if the voltage gets too low. . This was not an issue at first installation with the magnetic mount. 

What is a good brand of ferrite beads to get, I imagine its pretty easy to sell something like it which will do nothing for me. 

[WRYZ926]

I get mine from Amazon and they work just fine.

60 Pieces Clip-on Ferrite Ring Core RFI EMI Noise Suppressor Cable Clip

I like that it comes with quite a few different sizes. I use the smaller ones in my shack for computer cables to help with noise since I run my VHF/UHF, GMRS, and a HF radio in my office/shack. They are a. must if one runs any type of digital modes on HF.

Are you using the exact same antenna with both mounts?

Do you have another antenna to try? That would eliminate the antenna or the NMO mount as a problem.

If antenna height is a concern, you can try something like the Tram 1174 which is a 5/8 wave antenna and is still only about 16" tall. It will need to be cut/tuned though. While those 1/4 wave stealth antennas do work, a 1/2 wave or 5/8 wave will work better.

[WRTZ361]

15 minutes ago, WRYZ926 said:

I get mine from Amazon and they work just fine.

60 Pieces Clip-on Ferrite Ring Core RFI EMI Noise Suppressor Cable Clip

I like that it comes with quite a few different sizes. I use the smaller ones in my shack for computer cables to help with noise since I run my VHF/UHF, GMRS, and a HF radio in my office/shack. They are a. must if one runs any type of digital modes on HF.

Are you suing the exact same antenna with both mounts?

Do you have another antenna to try? That would eliminate the antenna or the NMO mount as a problem.

If antenna height is a concern, you can try something like the Tram 1174 which is a 5/8 wave antenna and is still only about 16" tall. It will need to be cut/tuned though. While those 1/4 wave stealth antennas do work, a 1/2 wave or 5/8 wave will work better.

This is all really good info, thank you. I don't have any spare pieces for a build like this. This is my first attempt at making a mobile setup. It is the same antenna. the only thing that changed was the cable mount combo. They both had the cable built into the mount. I didn't make my own. 

The height of the antenna is not a concern for me. I am more concerned with performance, Hopefully the beads help. Is there such a thing as too many beads or putting them in the wrong locations?

[WRYZ926]

Well that depends on the amount of RFI/EMI you are getting. Most of the time you can get away with two per cable. I like to put one on each end of the cable. I don't know if that would be possible with your NMO mount. 

HF frequencies are a different animal and more ferrite beads will help. 5 to 7 clamp on ferrite beads seems to work the best for HF. Normally 2 works fine for VHF and UHF. Again one on each end of the coax when possible.

When it comes to power cables, it is best if you can use a large enough ferrite bead to get at least three wraps of the power wires in them. If you don't have the room, then don't sweat it. Again put a ferrite bead on each end. I also did the same with the cable from the alternator to the battery - one on each end. I do suggest wrapping the clamp on ferrite beads with electrical tape or even zip ties to reduce the risk of them falling off.

From the sounds of things, I wonder if you have a bad NMO mount or bad coax cable since everything else is the same as before. Look for any cold solder joints at all the connections. Cold solder joints are usually dull looking. A good solder joint will look shiny when new.

I suggest going with a 1/2 or 5/8 wave antenna. Even a bottom loaded 5/8 wave like the Tram 1174 will be better than a 1/4 wave antenna. And if you can run a 35" long antenna, then the Midland MXTA26 is a good choice.

[WRYZ926]

I forgot to ask. Where do you have the antenna mounted? Is it in the center of the roof or on the side?

[wayoverthere]

4 hours ago, SteveShannon said:

I don’t see anything there that makes me cringe.  The radio is as good of a GMRS certified radio as you can get.  The Midland mount is okay.  It’s nice to install because it only requires a 3/8” hole. It might not be “commercial radio” quality like a police car or ambulance would get, but it should be fine.  If it fails then ask one of the guys like Kenny what NMO mount they use in a public safety vehicle where price is no object and reliability is the only concern.  
The Melowave antenna is not one I’m familiar with, but I have seen them sold on one of the buy two way radios websites.  There’s no reason to doubt it, but as far as I know it’s strictly GMRS.

The other nice aspect of that Midland cable is the adapter on the radio side, when mounting outside the cabin. I'm using that mount/cable on a fender bracket, and the ability to uncrew the pl259 end lets it slip through a firewall grommet more easily.

Adding to this ...searched the antenna, not a fan of the phantom/stealth type...limited testing with a laird on a mag mount performed worse than a handheld with the stock rubber duck antenna.

That said, I haven't heard complaints about lack of quality with that brand, so I don't think it's the source of this issue at this point

Edited October 27 by wayoverthere
adding about antenna

[WRTZ361]

16 minutes ago, WRYZ926 said:

I forgot to ask. Where do you have the antenna mounted? Is it in the center of the roof or on the side?

I have it centered on my roof. The roof is steel, and I tried to get the teeth on the bottom of the NMO base to bite into the metal. I looked for solder joints anywhere and I do not see anything visible. everything has shrink tube or plastic overmolding. 

[WRTZ361]

45 minutes ago, wayoverthere said:

The other nice aspect of that Midland cable is the adapter on the radio side, when mounting outside the cabin. I'm using that mount/cable on a fender bracket, and the ability to uncrew the pl259 end lets it slip through a firewall grommet more easily.

Adding to this ...searched the antenna, not a fan of the phantom/stealth type...limited testing with a laird on a mag mount performed worse than a handheld with the stock rubber duck antenna.

That said, I haven't heard complaints about lack of quality with that brand, so I don't think it's the source of this issue at this point

I was thinking of switching to Nagoya or tram. I like the Nagoya antennas on my HT. Don't know if that will translate to the mobile antennas though. 

[nokones]

The Midland Magmount really isn't too shabby. I have found that I have gotten good VSWRs with the Midland NMO Magmount. The radio shouldn't be the problem, but I can't vouch for the Antenna. The VSWRs definitely need to be checked.

[nokones]

The Midland MXTA 26 is also good performing GMRS antenna

[wayoverthere]

6 hours ago, WRTZ361 said:

I was thinking of switching to Nagoya or tram. I like the Nagoya antennas on my HT. Don't know if that will translate to the mobile antennas though. 

Same story here with nagoya, solid HT antennas, but haven't used the mobiles. What I have used (mostly on midland's mag mounts):

• Tram 1181, sold as a wide coverage dual band.  So-so results, but good on the swr. I was compromising for the lower height.
• Midland's old 3db whip (mxta10, base loaded 5/8 wave, according to BTWR). Worked well for its size.
• Browning br1713bs, double 5/8 wave uhf only antenna, rated for 410-480mhz, iirc. worked great, but larger size (32") akin to midland's mxta26.
• Laird 1/4 wave for 450-470mhz, decent performer; this would be my limited clearance go-to on the current truck, since even the 12" mxta10 is too much height for the work garage. On the old (smaller) truck, I ran the mxta10 for limited clearance, or the Browning when I wasn't limited.
• Comet 2x4SR, little higher swr than the uhf only, in trade for the wide coverage; ran this for a bit with 2 radios and a duplexer; it's currently doing ham duty on the truck on a comet bracket and Midland cable/nmo.

On the ham side of things, I've also used Laird's base loaded 1/2 wave for UHF (tuned for 430-450 mhz, again on the Midland mag mounts), and it worked very well, and the reasonably small size (around 12") fit almost everywhere on my old truck. 

If I didn't have that Midland whip, I wouldn't hesitate to grab another Laird to cover GMRS (they have 450-470mhz versions in various sizes, with and without spring).  I'd also have no qualms recommending that Browning, thought searching the model number showed sparse availability last I looked, so it may be discontinued like the mxta10).

[gortex2]

Make sure the center pin of your antenna is actually touching the NMO center pin. Alot of times the mount is not instaleld right and depending on antenna it may not touch. The old larsen wouldh ave this issue when swapping between vehiles. The metal tab would bend up after years on the vehicle then the new mount would not touch. 

[nokones]

9 hours ago, wayoverthere said:

Same story here with nagoya, solid HT antennas, but haven't used the mobiles. What I have used (mostly on midland's mag mounts):

• Tram 1181, sold as a wide coverage dual band.  So-so results, but good on the swr. I was compromising for the lower height.
• Midland's old 3db whip (mxta10, base loaded 5/8 wave, according to BTWR). Worked well for its size.
• Browning br1713bs, double 5/8 wave uhf only antenna, rated for 410-480mhz, iirc. worked great, but larger size (32") akin to midland's mxta26.
• Laird 1/4 wave for 450-470mhz, decent performer; this would be my limited clearance go-to on the current truck, since even the 12" mxta10 is too much height for the work garage. On the old (smaller) truck, I ran the mxta10 for limited clearance, or the Browning when I wasn't limited.
• Comet 2x4SR, little higher swr than the uhf only, in trade for the wide coverage; ran this for a bit with 2 radios and a duplexer; it's currently doing ham duty on the truck on a comet bracket and Midland cable/nmo.

On the ham side of things, I've also used Laird's base loaded 1/2 wave for UHF (tuned for 430-450 mhz, again on the Midland mag mounts), and it worked very well, and the reasonably small size (around 12") fit almost everywhere on my old truck. 

If I didn't have that Midland whip, I wouldn't hesitate to grab another Laird to cover GMRS (they have 450-470mhz versions in various sizes, with and without spring).  I'd also have no qualms recommending that Browning, thought searching the model number showed sparse availability last I looked, so it may be discontinued like the mxta10).

I have found that the Midland Mag-Mounts have the best results for VSWRs on GMRS freqs than any other brand of Mag-Mounts, even better than Laird.

[SteveShannon]

12 minutes ago, nokones said:

I have found that the Midland Mag-Mounts have the best results for VSWRs on GMRS freqs than any other brand of Mag-Mounts, even better than Laird.

I’ve had decent results with the Midland mag mount.  My friend down the street picked up a Comet mag mount and it seems to work very well also. Both of us use the Comet SBB5 for 2 meter and 70 cm and I use the Midland MXTA26 for GMRS. 

[SteveShannon]

1 hour ago, SteveShannon said:

I’ve had decent results with the Midland mag mount.  My friend down the street picked up a Comet mag mount and it seems to work very well also. Both of us use the Comet SBB5 for 2 meter and 70 cm and I use the Midland MXTA26 for GMRS. 

But really I’m just building up the nerve to install permanent NMO mounts in the roofs of my pickup and my 4Runner.

I saw a comment on a YouTube video yesterday where a person attempted to denigrate the YouTuber for punching a hole in the roof of his new truck.  It made me wonder again why we own vehicles. Aren’t these vehicles supposed to improve our lives?  I would argue that in at least an incremental way, having an antenna permanently mounted, with neatly hidden coax and a nice mount for the radio makes our lives better than having to worry about the coax whipping around in the wind at highway speeds. 

[wayoverthere]

1 hour ago, nokones said:

I have found that the Midland Mag-Mounts have the best results for VSWRs on GMRS freqs than any other brand of Mag-Mounts, even better than Laird.

They've worked well (and hold well) for me, to the point that 4 of my 5 are Midland (between up to 3 at a time on the old truck, one stashed in the better half's car, and one used for a base (on sheet metal for a ground plane). The other is a browning, because I wanted to try one with rg-8x cable. No difference that I could tell , but it held well also.

1 hour ago, SteveShannon said:

I’ve had decent results with the Midland mag mount.  My friend down the street picked up a Comet mag mount and it seems to work very well also. Both of us use the Comet SBB5 for 2 meter and 70 cm and I use the Midland MXTA26 for GMRS. 

Comet have worked well for me on the ham side...the one diamond I tried, not so much (nr72b, if I remember right)

[gortex2]

@SteveShannon as you are aware a properly installed NMO will not leak nor casue issues with resale trade in value. Other than my Jeeps every vehicle I have owned for 30+ years has had NMO mounts in the roofs. On my last F150 (2020) it had 6 NMO plus 2 GPS antenna's. My previous F150 (2019) had 4 mounts and the dealer never said a word when I traded it in. I put black NMO caps on them and I am sure no one even realized they were there. I've probably installed over a thousand NMO mounts sinces I've been in 2 way radio and in the end its always the right choice. As said I like the simple approach of not seeing cables, worring about cables etc. I drive thru car washes all the time and I'd definately not do that with a mag mount. I'm definately team drill it.... (btw...even my 2023 Scat has a NMO in the trunk for a 1/4 wave VHF...)