BCD996XT Noise Issue

[MikeSD]

I have a BCD396XT and run it from AC adapter, and it works fine.

I just bought a BCD996XT and also run it from the AC adapter, and monitor the very same channels but there is noise everywhere. Even if I turn the squelch to 10, many frequencies still show noise, where my 396XT is dead quiet. Same with some of my other radios. I only have this problem with my 996XT.

Is this just a grounding issue? Might the scanner be defective? Why such a difference between these two scanners? I wonder in general whether a seperate earth ground should be required with the 996XT. I don't have this issue with any of my other radios. There is absolutely no mention of this (or supplying power) to the scanner in the manuals.

Do you have to use a seperate earth ground to your 996XT?

 

[pdw911]

You didn't indicate...are you using different power supplies for each scanner? Are you using the power supply that came with the 996 (the one with the toroid coil-supresses noise)?

1. Could be power supply...try another
2. Power with 12VDC from a battery- do you still have noise?

Noise from both sources- you either have an envrionmental issue not being filtered by the 996 or a bad 996

If the noise is only present when any plug in supply is used the ground reference in the scanner may be bad (usually inside solder joint)

or (and this is a real reach)- the 120VAC source is dirty...try another 120VAC source....preferably from another distibution panel

 

[MikeSD]

You didn't indicate...are you using different power supplies for each scanner? Are you using the power supply that came with the 996 (the one with the toroid coil-supresses noise)?

Same one that came with the scanner.

1. Could be power supply...try another
2. Power with 12VDC from a battery- do you still have noise?

Good idea. I did run it from a DC supply vs. the adapter and it runs better but still noisy. I'll get a sealed lead acid battery and try that.

Noise from both sources- you either have an envrionmental issue not being filtered by the 996 or a bad 996

If the noise is only present when any plug in supply is used the ground reference in the scanner may be bad (usually inside solder joint)

or (and this is a real reach)- the 120VAC source is dirty...try another 120VAC source....preferably from another distibution panel

I suspect my household ground is not really a good earth ground. I'm also going to run a wire out the window (temporarily) connected to a solid earth ground, using a ground rod pounded into the ground. I need that anyway, for my HF stuff. That should tell me what I need. If it's grounding, I'll bore a hole to the outside (should make my wife happy ) and run the wire through a box.

Thanks,

 

[pdw911]

That is pretty radical. If you have issues with your ground/neutral floating you have bigger safety issues in your house

You also didn’t mention if the noise is present with an external antenna or with the telescopic antenna that came with the unit. It isn’t likely, but you might have a ground loop in an external antenna where the shield isn’t good

 

[MikeSD]

That is pretty radical. If you have issues with your ground/neutral floating you have bigger safety issues in your house

You also didn’t mention if the noise is present with an external antenna or with the telescopic antenna that came with the unit. It isn’t likely, but you might have a ground loop in an external antenna where the shield isn’t good

I didn't say it was a floating ground. But it could very well be a ground issue, since I'm connecting my scanner to my computer and both are referenced to the house ground, through these adapters. So the radio is likely seeing a slightly different ground that the computer. There is zero safety issue.

I'm using the antennas that are supplied with the radios. When I use my 396XT, on AC, with internal antenna, it receives fine. But it is really being powered by the batteries. When I use the 996XT, I pick up a lot of noise that appears to break squelch. It too is using the internal antenna. When I power the 996XT, from a DC power supply, using the supplied DC cable, the reception is better but not as good as the 396XT. When I use the AC adapter supplied with the 996XT it's very bad. This suggests grounding issue.

All radios and all systems connected together need to be referenced to the same ground, for optimum performance. I've seen this before. Different paths (connections) to ground can cause anomalies, both in radiated noise and susceptibility to noise.

I have an IRLP node. When I connect that radio to an AC source using the supplied adapter, and the computer to an AC source, using an different adapter, it too will see squelch breaking, from noise. But when I reference it to the same ground as the computer it's connected to, the noise goes away. That is why I believe this might be a ground issue. You can also see these kind of issues in vehicles when you use a ground other than the direct battery ground.

What I am doing is using my scanner to monitor an amateur radio setup. I have already determined that the noise isn't actually coming over the amateur radios. But I have several pieces of equipment all connected to the same AC system, using individual addapters and power supplies. That is why I will be testing the ground.

This is my system.

And this is the link to listen to whatever might be happening. Not always a lot of traffic. But it allows me to monitor my system.

http://stn7681.ip.irlp.net:8282

If I substitute a 996XT for the 396XT, in the diagram, I start picking up a lot of noise on the scanner (squelch control doesn't help). But if the 396XT is there, it works fine. I only posted this question to see if others have seen this or if this is a particular issue with the 996XT.

Mike
KC7VE

 

[pdw911]

Possible...but this isn't 1965 where sterio systems and turn tables all had to be strapped..you shouldn't have to go to such measures..but you can't hurt anything (unless you have voltage superimposed on the ground)...setting a proper depth ground rod will isolate the ground for sure

(You are connected to computer...you mean audio or are you plugging the power supply into one of the service outlets on the back of a pc)

If you don't connect to anything (this elimates any backfeeding from other sources (PC fan motor etc, bad cable to PC), use just the power supply and the antenna that comes with the unit and you have noise...the easy solution is bad power supply...more complex is that the filtering in the scanner is bad and you need a warranty replacement (good check is to find someone that also has a 996xt and see if it is environmental)

 

[pdw911]

I assume you moved the scanner and power supply to another location to eliminate any "local" intereference