Scanner Audio has hum when hooked up to computer.

Ok, I don't really know where to post this so why not with the locals! I have a delima. I just put up an Antennacraft ST-2 antenna on the roof. It's grounded properly and the coax is grounded properly too. Wonderfull reception too. With the antenna hooked up to the scanner, audio is fine. No hum noise. When I hook up my 1/8" jack connection cable to the line in on my soundcard, I have the hum noise. If I then unhook the OUTSIDE antenna, hum goes away. I thought maybe its from the antenna. But why wouldn't it make the hum noise thought the scanner's speaker?? Also if I swap antennas to the rubber duckie, no noise through compy. Also, with the outside antenna hooked up and the noise is present, if I push slightly on the audio cable going into the soundcard, the audio switches channels to the right from the left and the noise stops. I'm thinking I might have a bad soundcard or 1/8" audio cable.

Sorry this is so long but I pulling my hair out. It sounds reaaaaly annoying to listen too. If anyone can, please point me in the right direction!! Thanks in advance!!

Bbbbzzzz

Sounds like you have a ground loop issue, try grounding the case of your computer to the same ground as the shield of your coax, just run a peice of scrap wire from a screw on the case.

Mark Mc.

Worked like a charm!

Thanks for your help firemedic. It worked perfectly. No more buzz and sounds even better than before. I appreciate the help!!

Hum problem. Wow!

What a solution. Kudos to Mark for this answer and I'm not even involved. Sometimes it's the simple things. I was going to suggest a bad mini-plug connection but I would have lost. I'd never heard of a "ground loop".
Ron

Ground loops....

Ground loops are common in cars when you have several diffrent electronic devices grounded to diffrent places on the chassis...you can actually develop a potential between grounds and create a current that flows through the equipment using the "common" ground, this causes the audible hummmmmm......

Mark Mc.

I was shooting for that being the problem and hoping it was. I really didnt want to get a new sound card. What threw me off was when I would move the audio cable in the soundcard. But what it was doing was switching channels from left to right. the sound was audible in only one channel. But anyway, thanks again for the help. Sounds a million times better!!!

Thats Check.

Do they still use that in Memphis?

Mark Mc.

firemedic2150 said:

Thats Check.

Do they still use that in Memphis?

Mark Mc.

Click to expand...

Everyday!!!

Sorry to revive an old thread but I'm having the same problem and hooking up my computer case into the same ground as my coax/antenna did not work. The audio quality actually got worse, its awful now.

East Central IL and West Central IN Counties Public Safety Live Audio Feed

Listen here, any ideas?

What you need is a ground loop isolator between the audio output of your scanner and the input on the computer, like this:

4 Channel Ground Loop Isolator - Monoprice.com

This one is for four separate signals, but it can be used for just one - and the price is cheap at $7.85.

flythunderbird said:

What you need is a ground loop isolator between the audio output of your scanner and the input on the computer, like this:

4 Channel Ground Loop Isolator - Monoprice.com

This one is for four separate signals, but it can be used for just one - and the price is cheap at $7.85.

Click to expand...

Sweet thanks, will this work even if I just use a single audio cable to stream and not the RCA inputs?

Also, should I leave my computer case grounded since it didn't fix anything?

Thanks again.

I had a hum issue too, no matter what I did I couldn't get rid of it. Grounded, changed cables, outlets, antennas, moved around the gear, tried a brute-force filter, even a laptop on battery, but the hum was ever-present. I began to wonder how anyone can avoid it!

I figure it was the radio and gave up trying. Later I got a receiver that overcame the issue. The one thing that "fixed" it for me was to avoid audio cables altogether. Use an RTLSDR dongle. Plugs into the USB port. Lots of folks here I'm sure are familiar with them. All digital, zero hum. No cables needed. The dongle costs about $20, software is free.


Oh, also allows one to monitor as many freqs as yo like within about a 2meg slice of spectrum. I once fed 3 amateur radio repeaters simultaneously with a single RTLSDR. You can have as many "VFO"s as your like.

Small too, my entire server is about the size of a desktop scanner.

Just remember to do trunking, you need SDR Trunk, and multiple dongles to run it from everything I can tell.

I corrected my hum issue by using a mono audio cable. Haven't had a problem since.


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