static

[steved]

I think the answer to my problem is lack of chassis grounds...

I have static in my receive, a lot of it, as in around 7 S-units. I figured it was from a cellphone charger and XM receiver (unplug either one and it subsided). However, I can also simply place my hand on the radio and the noise decreases.

The radio is a HongKong 29 (similar to a Philippines), the setup is a 29/2-pill/Wilson 1000. The only grounds either the 29 or the 2-pill have are through their respective power leads (the radio is mounted to a plastic console, and the 2-pill is sitting on the floor). The 1000 has an added ground wire from the magnet's bolt to the vehicle's body. It does this regardless of whether the 2-pill is hooked up or not, so the amp is not likely the issue.

I'm figuring that since the chassis isn't ground well, the case isn't blocking errant RF? And by touching it, I'm closing the "ground" circuit?

Does this sound plausible?

 

[Beetle]

When all the noise is happening, what happens if you disconnect your radio's antenna and unplug it?

 

[steved]

When all the noise is happening, what happens if you disconnect your radio's antenna and unplug it?

Have not tried that, will do that on the ride home tonight...

I guess I don't understand why touching the radio causes the static to decrease...and it is consistent, I touch the radio and the noise decreases every time.

 

[BOOTY MONSTER]

disconnecting the antenna will tell you if the noise is comming in through the antenna/coax or the electrical system . always good to know where/what to fix befor just changing things

 

[steved]

I understand that, but if it was coming in through the antenna, touching the radio should make no difference?

 

[freecell]

just follow the booty man's instructions and let us know the results. in the meantime maybe you can explain to us just exactly how the dc power connections are routed. you most likely have multiple installation errors contributing to this.

 

[steved]

Some background: I've had this 29 in here before without this problem, then a 3300HP, then a Cobra25, and my Uniden 76. I put the 29 back in after trading some radios...I intend to install a Uniden Grant before too long.

The only one that had issues was the 25, and it was ignition noise coming through the power leads. All these radios used the same power leads and same antenna (coax was replaced a year ago). Things that changed since then were the addition of the XM receiver, that's about it..the XM is causing the noise and touching the radio makes most of it go away. And just to clarify, its not ignition noise I'm hearing, its white noise.

The radio is hooked into the car's "accessory on" circuit, not the best but it has not provided any issues until this. In fact, its the same power cord I've used on all the others. It is a soldered connection with a 7A inline fuse.

The amp, again I've had it completely out of the circuit, is direct to the battery...number 8 wire, 40A fuse, and a set of quick connects at the amp. As stated, the symptoms exist with the amp sitting on the bench in my garage and the car driving down the highway...so I'm confident that its not causing any of these symptoms.

 

[freecell]

just follow the booty man's instructions and let us know the results.

 

[steved]

With the antenna disconnected, no noise. Even with the gain up and the NB off, I only get a very faint sizzle. And you need to really listen to here that.

Plug the antenna in and I have 7 s-units of white noise. Touch the radio or the mic and it drops significantly. I found tonight that by touching the screen on the skythumper, the noise drops to an expected 1 s-unit. I also found that just touching the mic cord will drop the noise level. That's a 6 point drop.

And just to make the point, this is a DTB radio-tuned radio. Not some hack special. And I don't think its the radio by any stretch of the imagination.

 

[steved]

With the antenna disconnected, no noise. Even with the gain up and the NB off, I only get a very faint sizzle. And you need to really listen to here that.

Plug the antenna in and I have 7 s-units of white noise. Touch the radio or the mic and it drops significantly. I found tonight that by touching the screen on the skythumper, the noise drops to an expected 1 s-unit. I also found that just touching the mic cord will drop the noise level. That's a 6 point drop.

And just to make the point, this is a DTB radio-tuned radio. Not some hack special. And I don't think its the radio by any stretch of the imagination.

 

[steved]

OK, that's VERY strange...I got errors both times I tried to submit the above post from my crackberry...and yet they posted???

 

[steved]

I'm thinking I need to ground the radio chassis?? Thoughts?

 

[Beetle]

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.

 

[formulamojo]

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.

 

[dcdeepwoods]

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?