CB RF Problem

[911outfitters]

I am new to this so please excuse me if I ask to much...I have an officer who we insatll a Galaxy DX99V in his patrol car...however now when he talks on it all the items plugged in thru usb ports to his Datalux MDT computer go dead...he can unplug them and the work again until he keys up again....any help or suggestions ...Thank you

 

[SCPD]

Similar problem here. However this occurs on a home computer with only the bluetooth getting knocked off and as you said unplugging usb and plugging back up again will work.
I moved the cables around and that had helped. First thing I noticed was when the computer was on that there was an increase in noise level on the CB Radio. Grabbing the usb cables by hand and I would notice the noise level decreasing. See if that is the case. Only solution so far was to reroute the cable. Not sure if there may be some way of making an RF Choke for this solution. As I'd said, the noise level would increase when the computer is on. Meter on the radio would go to half scale and grabbing the cable to the usb blutetooth and the mouse would drop the noise somewhat. Now when I key it no longer knocks it off.
It can be a little frustrating isolating the problem. I'm sure moving the cables if at all possible might help. Only problem he may have is the room to move things.
Someone with more knowledge of this could give you more help.

 

[kc8kek]

CB in police car

The first thing I would recomend doing is replacing the Galaxy radio with an actual CB radio. If you're putting this into a police car, you probably want a radio that is first of all not illegal, and secondly, not going to interfere with everything within a hundred feet of it.

Depending on who "peaked and tuned" the radio (which is why you buy that radio, so that's probably been done), it probably leaks a lot of RF into parts of the spectrum it shouldn't, and you can expect it to continue to cause interference - not only inside the patrol car, but also outside (gas station intercoms, drive-throughs, ect.).

I'm always happy to see a police car with a CB - it gives them a way to keep in touch with the motoring public. However, I wouldn't want to explain to my boss why my illegal "CB radio" is causing the city's very expensive MDT to keep malfunctioning.

In my opinion, the best bet is to tell the officer to put his "CB" back in his pickup truck and get a stock Cobra or Uniden CB online and use that for his patrol car.

Just my opinion though.

 

[datainmotion]

Yep - my understanding is that the FCC considers the DX99v a non type-certified radio for 11m use. Plus, as the previous post intoned, it is most likely putting out more than the legal 4W AM limit, as well as all sorts of spurious garbage. I'd suggest a nice, untouched Uniden pro-520 or similar radio.

 

[SCPD]

You are right kc8kek about the Galaxy DX99V. It is a 10 meter radio and would have had to of been modded just to have 11 meter CB channels. I forgot about that model of Galaxy radio. I think the DX 949 was a legal CB only radio that they made.
I have a stock Navaho that was knocking out my bluetooth. My radio was never modded in anyway. Still original, never peaked and tuned and the mod limiter is still in it. Moving my wires solved some of the problem.
So I guess the RF problem could still exist even if there was a change in the type of radio being used.

 

[WouffHong]

Splatter city

AMEN and AMEN!! :evil:

The first thing I would recomend doing is replacing the Galaxy radio with an actual CB radio. If you're putting this into a police car, you probably want a radio that is first of all not illegal, and secondly, not going to interfere with everything within a hundred feet of it.

Depending on who "peaked and tuned" the radio (which is why you buy that radio, so that's probably been done), it probably leaks a lot of RF into parts of the spectrum it shouldn't, and you can expect it to continue to cause interference - not only inside the patrol car, but also outside (gas station intercoms, drive-throughs, ect.).

I'm always happy to see a police car with a CB - it gives them a way to keep in touch with the motoring public. However, I wouldn't want to explain to my boss why my illegal "CB radio" is causing the city's very expensive MDT to keep malfunctioning.

In my opinion, the best bet is to tell the officer to put his "CB" back in his pickup truck and get a stock Cobra or Uniden CB online and use that for his patrol car.

Just my opinion though.

 

[KC4RAF]

As others noted,

non-certified equipment. Click on the link below and read paragragh 5 which mentions the Galaxy Model DX99V in question. Some serious dollars were mentioned in the NAL, so be aware of how much it could cost you and the officer. He could lose his job too.

http://transition.fcc.gov/eb/Orders/2008/DA-08-597A1.html

Best bet, get a Cobra, Uniden, RS, or any other type accepted CB.

Just my two cents worth....

 

[datainmotion]

I think the DX 949 was a legal CB only radio that they made.

The 959 was type-accepted for CB as well.

 

[jim202]

A couple of things to ponder on this problem and haven't been mentioned yet.

Have you put an SWR meter on the coax cable at the radio and measured both forward and reflected power? The more reflected power, the more problems your going to have. Need to make sure the antenna system is working as well as it can. You can't solve RF problems if the antenna system is poor.

You didn't mention what kind of an antenna was being used or where it was located. If the antenna has a poor ground, it will try and use the coax cable as a ground. This just brings the RF right back to the radio rather than being radiated by the antenna.

If the antenna is mounted on the trunk lid of the vehicle, you probably have a poor ground back to the body. I would add some copper braid jumpers around the hinges to rectify this problem. Had a vehicle a number of years back that had a low band 100 watt radio mounted in it. The antenna was on the trunk lid. When the radio was keyed, the engine would shut down. Adding the ground jumpers on the trunk lid to the body solved that problem.

If after you fix all the grounding and antenna issues and you still have the computer USB problem, the next step would be to add some ferrite cores on the USB cables. Have had to do that with other equipment that would be bothered by VHF hand held public safety radios. After adding the snap on ferrite cores, it never saw the problems again.

So if you take a few moments to go over your installation, I am sure you can solve all your problems.

 

[JayMojave]

Hello 911Outfitters: A great posting by Jim202 there.

You need to verify the antenna is working ok, and not having a lot of SWR. I have used thge Wilson 1000 and 5000 antennas with much success. I tried a few times to get a 2000 to work, but ended up going back to the 1000 or 5000 Wilson Antennas.

Transmitting into a 50 Ohm dummy load, and not seeing the interference issue will tell you if you have a possible antenna SWR or local field overload condition. The snap on ferrite cores are good call, avialable at Radio Shack.

Good Luck

Jay in the Mojave

 

[SurgePGH]

The first thing I would recomend doing is replacing the Galaxy radio with an actual CB radio. If you're putting this into a police car, you probably want a radio that is first of all not illegal, and secondly, not going to interfere with everything within a hundred feet of it.

Depending on who "peaked and tuned" the radio (which is why you buy that radio, so that's probably been done), it probably leaks a lot of RF into parts of the spectrum it shouldn't, and you can expect it to continue to cause interference - not only inside the patrol car, but also outside (gas station intercoms, drive-throughs, ect.).

I'm always happy to see a police car with a CB - it gives them a way to keep in touch with the motoring public. However, I wouldn't want to explain to my boss why my illegal "CB radio" is causing the city's very expensive MDT to keep malfunctioning.

In my opinion, the best bet is to tell the officer to put his "CB" back in his pickup truck and get a stock Cobra or Uniden CB online and use that for his patrol car.

Just my opinion though.

+1 You installed an illegal electronic device into a POLICE OFFICERS vehicle??? WOW!
The legal ramifications could cost the officer his job and you a ***** ton of money in FCC fines. I would imagine that if the radio damages the MDT and it falls back to you that you would face legal action and restitution to replace the damaged equipment, not to mention the bad name that you would bring to your company for other customers and/ or potential customers....

Where's my popcorn???? I wanna see this unfold....

 

[prcguy]

The OP problem has nothing to do the the Galaxy radio not being type accepted or putting out a little more power than a stock CB. RF is getting into the computer wiring and checking the antenna and adding ferrite cores as mentioned are the basic fixes.

It would not be possible to mistune a CB to put out any perceivable energy in the 2.4GHz band used by Bluetooth or any other wireless computer device.

I do agree a stock CB should be put in for legal reasons. What's next, the officer is going to illegally mod his AR-15 to full auto and carry on duty?
prcguy

+1 You installed an illegal electronic device into a POLICE OFFICERS vehicle??? WOW!
The legal ramifications could cost the officer his job and you a ***** ton of money in FCC fines. I would imagine that if the radio damages the MDT and it falls back to you that you would face legal action and restitution to replace the damaged equipment, not to mention the bad name that you would bring to your company for other customers and/ or potential customers....

Where's my popcorn???? I wanna see this unfold....

 

[SurgePGH]

The OP problem has nothing to do the the Galaxy radio not being type accepted or putting out a little more power than a stock CB. RF is getting into the computer wiring and checking the antenna and adding ferrite cores as mentioned are the basic fixes.

It would not be possible to mistune a CB to put out any perceivable energy in the 2.4GHz band used by Bluetooth or any other wireless computer device.

I do agree a stock CB should be put in for legal reasons. What's next, the officer is going to illegally mod his AR-15 to full auto and carry on duty?
prcguy

It could have everything to do with it... If it is a 10 Meter radio modified to do 11 Meters it could be throwing spurs all over the place. There is a reason that radio is not type accepted. It might not be shielded properly. A 'little more power than a stock CB'???? It is rated at 10 Watts A.M. BEFORE any mods. Bottom line is that the radio is not type accepted and it is not type accepted for a reason or reasons.

 

[prcguy]

If you misalign a CB it can have excessive harmonic output on odd and even harmonics but they diminish rapidly as you get to the higher order and after about the 7th harmonic there would be nothing to measure.

The 7th harmonic of 27MHz is only 189MHz and quite far from 2.4GHz where the patrol car computer might have some wireless stuff. Harmonics, even purposely made bad ones would be difficult to generate at more than about -15 or -20dB below the fundamental frequency. 20dB below 10 watts is 100mw and insignificant compared to the fundamental carrier as far as RF ingress to computer cables.

The basic problem is probably some common mode RF on the outside of the coax leaking into nearby computer cables and stripping it off with ferrite chokes or going from a mag mount antenna to something better will probably fix it.

The difference between the 10w carrier output of the Galaxy and a stock CB is only about 3dB different and if thats all it takes to cure the problem then moving your body around inside the patrol car would probably have more effect than going to a stock CB.

I see a lot of CB folklore and misinformation leaks into technical discussions here and it can waste a lot of someones time changing things unnecessarily based on information that has little or no basis.

In my early years as a technician at the largest CB manufacturer on the planet (at the time) I've had my hands inside literally thousands of CBs and have seen just about everything that a CB can produce in power and harmonic energy by accident and on purpose.

I also worked at a very large volume CB shop and installed about 1,000 radios and repaired hundreds of problems dealing with RFI to and from radios so I'm not makin this stuff up.
prcguy

It could have everything to do with it... If it is a 10 Meter radio modified to do 11 Meters it could be throwing spurs all over the place. There is a reason that radio is not type accepted. It might not be shielded properly. A 'little more power than a stock CB'???? It is rated at 10 Watts A.M. BEFORE any mods. Bottom line is that the radio is not type accepted and it is not type accepted for a reason or reasons.

 

[gewecke]

I am new to this so please excuse me if I ask to much...I have an officer who we insatll a Galaxy DX99V in his patrol car...however now when he talks on it all the items plugged in thru usb ports to his Datalux MDT computer go dead...he can unplug them and the work again until he keys up again....any help or suggestions ...Thank you

Put a LEGAL cb in the squad, end of problems.
Nuff said!!


73,
n9zas

 

[LtDoc]

The RFI is caused by 'energy' getting into something it shouldn't be getting into. The 'cure' is to stop it from getting there. Simple, right? Well, the idea is simple, but the 'doing' of it it certainly may not be! The most common methods of doing that 'curing' is by shielding, suppression, and by-passing. None of those methods are infallible, and none are always easily done at times.
I figure if you guys do this for a living then you ought'a know about them to start with, right?
Good luck!
- 'Doc

 

[pjtnascar]

You probably should exchange that CB for a type approved radio, just to CYA. I agree with many of the other posters, however. The issue is not the fact that the radio is not FCC approved, but more likely because of the wire location or the SWR, or cheap poorly shielded coax on the antenna. Check those issues out, or you'll just have problems even with a legal radio in the car.

 

[grogan]

Remove all police equipment, Install Dave Made 50,000 watt linear with extra batterys in the trunk and 2-3 extra altanetors under the hood, Install the Rod of God antenna and you should have it made( well after an SWR check) Should be good to go WORLD WIDE WORLD WIDE...............

 

[grogan]

That was all in fun, not intended to make anyone mad.

 

[KC4RAF]

No problem with fun.

It makes for a better world to have some humor.
But I do like your suggestion on a 50KW linearrror!!!
And back on topic, get a Cobra. They are great little CBs...(and add the Dave made thiny as Grogan posed).