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Ground loop isolator not removing the hum from my feed.

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N_Jay

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Ground loop isolators only fix hum that is caused by a ground loop the includes the link they are isolating.

You need to find the source of the hum before you find the fix.
 

geeknik

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I've had this issue with all of my scanners, they all hum like this. Never been able to figure out why. Now when I put them in my car, no hum.
 

geeknik

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I don't have another power supply that I can try at this time. However, I will move the radio to another room and see if the hum improves.
 

04Z1V6

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I had this problem, It was a power supply on the other side of the house. I got a really good surge suppressor that also filters out noise and this helped.
 

w2lie

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I've found that using stereo cables from the scanner to the soundcard can cause a hum. Swapping to mono patch cables (the non-attenuating ones from RS) help.
Also, I've found it best to raise the volume on the radio just shy of clipping, and leaving the input volume on the soundcard low. If you raise the input volume too loud, and have the scanner volume too low, you'll be amplifying noise..

Good luck on the hunt.
 

VFN05

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Hum issue

Another possibility, although likely not the case in your situation, is a hum created by the backlight in the radio. I had an older Bearcat 260 that would do this. I say that this likely isn't your problem since you said the hum disappeared when you moved the radio into your vehicle. I agree with one of the earlier replies...the problem is likely related to a power supply or power line induced RFI.
 

Scan-Denver

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Using the Mic input instead of Line In on your sound card can also produce this affect. This configuration introduces line level voltage from your scanner that is more than what the Mic input was designed for.

If you are using the Line In on your sound card, try using battery power (assuming you are using a hand held) to try isolating the problem. If this works, there is one of two things you can do. 1, try a different power supply and 2, try an attenuating patch cord (available at Radio Shack) to be used between your scanner and your sound card.

Good luck!
 
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geeknik

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Thanks for the suggestions, I will give them a shot tomorrow when I can make another trip to Radio Shack. In the meantime, I'll leave the feed online as the radio traffic is audible over the noise, however annoying it may be. Hopefully will have this solved tomorrow. :)
 

NYRHKY94

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Do you have a powered sub-woofer attached to your PC? I've found that my Altec Lansing sub-woofer is the source for the hum I hear and the ground loop from RS would not solve the issue. Just a thought.
 

geeknik

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Do you have a powered sub-woofer attached to your PC? I've found that my Altec Lansing sub-woofer is the source for the hum I hear and the ground loop from RS would not solve the issue. Just a thought.
I tried disconnected all of my speakers, didn't work. Thanks though. ;)

Using the Mic input instead of Line In on your sound card can also produce this affect. This configuration introduces line level voltage from your scanner that is more than what the Mic input was designed for.

If you are using the Line In on your sound card, try using battery power (assuming you are using a hand held) to try isolating the problem. If this works, there is one of two things you can do. 1, try a different power supply and 2, try an attenuating patch cord (available at Radio Shack) to be used between your scanner and your sound card.

Good luck!
I'm using the line in. Can't use battery power as I don't have a handheld handy. I am going to pick up a different power supply and a new patch cord today. Thanks!

Another possibility, although likely not the case in your situation, is a hum created by the backlight in the radio. I had an older Bearcat 260 that would do this. I say that this likely isn't your problem since you said the hum disappeared when you moved the radio into your vehicle. I agree with one of the earlier replies...the problem is likely related to a power supply or power line induced RFI.
The backlight on this scanner is burned out, so I don't think it's the cause. Thanks!

I've found that using stereo cables from the scanner to the soundcard can cause a hum. Swapping to mono patch cables (the non-attenuating ones from RS) help.
Also, I've found it best to raise the volume on the radio just shy of clipping, and leaving the input volume on the soundcard low. If you raise the input volume too loud, and have the scanner volume too low, you'll be amplifying noise..

Good luck on the hunt.
I'm going right now to pick up a new patch cable right now. Thanks!
 

geeknik

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Ok. I wasn't able to acquire a new power supply for the scanner and a mono patch cable didn't solve the problem, so I am at a loss as how to continue.
 
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N_Jay

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Describe your set up so we can figure out a few logical places to start.

What you probably need to do is methodically open the various grounds in your set-up until the hum id gone, and then you will know where to start to fix the problem.
 

04Z1V6

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I've found it best to raise the volume on the radio just shy of clipping, and leaving the input volume on the soundcard low. If you raise the input volume too loud, and have the scanner volume too low, you'll be amplifying noise..

After listening to your feed this sounds like good advise. The hum is not that bad but I think we all try to put out the best feed we can.
 

geeknik

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Describe your set up so we can figure out a few logical places to start.

What you probably need to do is methodically open the various grounds in your set-up until the hum id gone, and then you will know where to start to fix the problem.
Pro-2066 connected to my PC via mono cable. PC is connected to an APC 1500VA UPS. Scanner is connected to an APC 350VA UPS. Electrical noise should be low as a result.

I do have CFLs in every room in the house, plus my front and back porch lights are LED.

As for everything else around the scanner and my PC: 3x 24" LCD monitors, 2x DSL modems, 1x 16 port gigabit switch, 4 linux servers, 1 windows server and 1 freebsd router.

I do plan on having an electrician out in the next couple of weeks to run a dedicated 200amp service to my "office" leaving the lighting on the circuit that is already in here. So hopefully by doing this, I can eliminate any spurious interference and just have my computer/scanner equipment on a circuit by itself.

I've found it best to raise the volume on the radio just shy of clipping, and leaving the input volume on the soundcard low. If you raise the input volume too loud, and have the scanner volume too low, you'll be amplifying noise..

After listening to your feed this sounds like good advise. The hum is not that bad but I think we all try to put out the best feed we can.
I've done that as best as I possibly could. The hum isn't near as bad as it started out to be. :)
 
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lbpd719

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I fooled with my primary feed for months before I was finally happy with the noise levels. The final magic touch was making my own shielded audio cable, using double shielded cables and tons of grounding..

Results are at http://69.239.28.85:8000 - would still like to get rid of the rest of the noise though, but I think I am pretty dang close. If you still have trouble after everything you try, get your hands on some good cable and get out your soldering iron..
 
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N_Jay

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Try simplifying the set up.
Get the UPS out of there (temporarily)

Plug both the scanner and the PC into the same outlet strip.

Disconnect EVERYTHING else that can be. (External antenna included)

See if you have hum?

If so it may be the scanner power supply. Try running it on a battery temporarily.

If not, then add connections back one at a time until the hum returns.
Then try disconnecting the connections you have one by one until it is gone.

You will then have identified it as either a true ground loop, and know what connections are involved in the loop, or as power supply hum.

Note, it can be both, and you can have more then one loop.

ave fun.

Try this with a recording studio, and you can kill a good week hunting it down.

Also, as you try thing METHODICALLY, try reversing the pug on any equipment that can be reversed.
You can also use a 2 prong adapter to (temporarily) unground three prong equipment.
 

bctrl1

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I think the important detail here is the pro-2066. This scanner has really poor supply filtering and wasn't really designed to be run off a wall-wart type power supply. If I remember correctly, the 2066 never came with a power supply for desktop use. Only a wire pigtail for mobile installation was provided.

I've owned a few 2066's and all of them required clean well regulated supplies to get hum-free audio. I'd start with a decent power supply before trying anything else.
 

GTR8000

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I just took a look and listen to a few of your archive files, and I'm not detecting anything at 60 Hz, which means this is likely not a ground loop issue. Or you may have a ground loop issue, but the Radio Shack filter is doing its job and eliminating it. You are having issues at 117 Hz and above, which points to something else causing the line noise.
 
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