static

[formulamojo]

I hate to jump on anothers post but I have a similar problem. I have tried every ground I can to take the noise out of my radio. Nothing seems to work. Tonight after reading this post, I unhooked the coax from my radio and the noise went away. Would this lead you to believe that the problem is in my coax or antenna? My SWR is great, always has been. Almost does not even move the gauge. Any thoughts?

What type of antenna?

 

[steved]

Here's a thought...

If the chassis ground isn't good enough wouldnt that indicated the radio isn't grounded as well as it should be?

Here's my logic on this...

The electrical DC ground for the radio is the chassis of the radio which is then linked to your vehicles ground through the power adapter to the cigarette lighter, battery, fuse box, or where ever you have decided to connect your radio.

So if pushing on the case stops the noise and is making you think you have a bad ground then maybe you should be looking inside the case at the power adapter and other places where the board grounds are connected.

If all those are good then start tracing it down the power line and also down the antenna coax.


To me a jumper wire is just a band aide. A quick fix to a bad ground.

A multimeter on continuity will be you most valuable tool on this job.

There is essentially no chassis ground in my setup, the mounting bracket is completely isolated on a plastic center console...there are essentially two electrical grounds, one through the power leads and the other through the coax shield braid. That's why I think I need to run a separate ground to the chassis/bracket of the radio.

I don't need to press or really even touch the radio...just gently laying a finger on it will cause the noise to decrease. At first I thought it was static...because the level decreases the closer you get to the radio...touch it and it all but goes away goes away. Just by touching the chrome-plated plastic knobs, the signal changes...which makes setting the RF gain a challenge to say the least...

I still think this is an RF ground issue and not a DC ground issue...by "grounding" the case, I essentially shield the internals of the radio from RF by providing a pathway from the radio...if that makes sense?

 

[steved]

Do it. Get a short (10-12 inch) piece of wire with an alligator clip on each end. Clip one end to the radio and the other end to a good ground. If there's a significant reduction in the noise level, you're moving in the right direction.

By the way, don't leave that wire there. Replace it with something more permanent and professional if the results indicate there's an improvement.

Are we talking normal electrical wire or braided strap...I guess I'm asking if you believe its a DC or an RF issue?

 

[steved]

I hate to jump on anothers post but I have a similar problem. I have tried every ground I can to take the noise out of my radio. Nothing seems to work. Tonight after reading this post, I unhooked the coax from my radio and the noise went away. Would this lead you to believe that the problem is in my coax or antenna? My SWR is great, always has been. Almost does not even move the gauge. Any thoughts?

May just be the nature of the beast...if you have errant RF entering the antenna, you either live with it or kill the source of the RF...

 

[formulamojo]

I meant the chassis of the radio not of your vehicle.

 

[74IN]

Are we talking normal electrical wire or braided strap...I guess I'm asking if you believe its a DC or an RF issue?

Yes, the flat braid is for RF, AC at high frequency runs on the outside of a conductor.

My guess is, since it's an RX problem, it might be a DC ground issue.

 

[BOOTY MONSTER]

since the noise is comming in through your antenna or feed line you could also make a RF sniffer and see if you can isolate where the noise is comming from .

Wilson Antenna Tech support - Test Equipment

 

[dcdeepwoods]

Ok here I go again with the jumping in on another post. I am running a 102". I have tried everything to ground the radio better but nothing works any better. My radio is mounted to plastic but I have the frame grounded to the truck frame. The antenna is on a tool box that I guess may not be grounded that well. Tomorrow I will be checking that. The other parts of the system are not grounded other than with the neg wire to the fuse box in the back of the truck. I have a multi post ground in the back of the truck and a multi post positive with 4 guauge running from the battery. The multi post neg goes straight to frame and not to battery. Everything has common ground from the multi post neg. I have had the same coax in the truck for about 8 years. SWR always been extremely low so I figured the ground on the box must have been good. Heck what do I know! Hopefully if I ground the toolbox better it takes away the noise but with my luck it will add more. I have had it so long and tried to fix it so many times that I am about ready to &@$! toss it out the window.

 

[steved]

I meant the chassis of the radio not of your vehicle.

Other than the covers possibly being isolated, there are soldered grounds to the radio chassis?

 

[steved]

Yes, the flat braid is for RF, AC at high frequency runs on the outside of a conductor.

My guess is, since it's an RX problem, it might be a DC ground issue.

OK, I will look into this further next week...busy weekend coming up.

 

[steved]

Ok here I go again with the jumping in on another post. I am running a 102". I have tried everything to ground the radio better but nothing works any better. My radio is mounted to plastic but I have the frame grounded to the truck frame. The antenna is on a tool box that I guess may not be grounded that well. Tomorrow I will be checking that. The other parts of the system are not grounded other than with the neg wire to the fuse box in the back of the truck. I have a multi post ground in the back of the truck and a multi post positive with 4 guauge running from the battery. The multi post neg goes straight to frame and not to battery. Everything has common ground from the multi post neg. I have had the same coax in the truck for about 8 years. SWR always been extremely low so I figured the ground on the box must have been good. Heck what do I know! Hopefully if I ground the toolbox better it takes away the noise but with my luck it will add more. I have had it so long and tried to fix it so many times that I am about ready to &@$! toss it out the window.

I ran a 2ga wire from the frame to the mounting bracket of my 102...it was also mounted to my toolbox. I know it wasn't a flat braid, but it worked.

And your coax might be bad...might consider changing it.

 

[Beetle]

My recommendation to use a short piece of wire is JUST AS A QUICK CHECK! If the noise doesn't go away, disconnect it; you're right back at square one. If the noise DOES go away, replace the temporary wire with a permanent one.

When you disconnect the antenna and the noise goes away, that does not automatically mean your antenna is at fault, nor your coax, neither your radio. It means that the noise is coming in VIA the antenna and not via the power leads.

It doesn't mean that a lot of "grounding" is in order, either. What it DOES mean is that something, probably under the hood, is generating electrical noise which is being radiated like RF and received by the antenna and thence to the radio. Your job then is to find out just what is generating the noise and filtering/bypassing the snot out of things to quiet it down. In cases like this, "grounding" is a waste of time.

 

[BOOTY MONSTER]

COUGH COUGH Wilson Antenna Tech support - Test Equipment COUGH COUGH

 

[steved]

Booty: I know where my noise is emanating from...the XM receiver/transmitter. That's not really my issue, as long as I place the mic face down on my leg or touch the radio, the noise subsides. That's not really antenna, is it??

To add to this puzzle, I installed another radio (a like new PC76) and the same thing happens. I also changed the mic (to another RK56-type knockoff, the first was a ST-DX65 and this is a 431-NC). So it might just be an installation issue as I believe freecell stated...

Tonight I took a length of coax, stripped the outer sheath and pulled the outer braid off. I remembered someone stating this was a fairly easy way to get a "flat strap braid". I soldered ends to the braid, and connected it to a body bolt and the radio's chassis screw. At the same time, I also installed a braid strap between the amp case, its ground lead, and the same body bolt.

Tomorrow will tell more, drive it to work and see if it helped or not...

 

[steved]

Well, not much change from adding the "ground" strap...if anything, it has made the noise increase.

I'm thinking I'm going to pull the power leads from the car's circuits and run straight to the battery...or maybe run the power leads to the battery, and switch it with a relay (so the radio turns off with the ignition). This would eliminate the car's wiring from the problem.