Pro-97 to line-in/mic loud humming

[kicktd]

Pro-97 to computer line-in loud humming

When I hook the Pro-97 up to my computers line-in or mic port (just to make sure it wasn't a line-in port problem) I get a very loud humming that only occurs when the antenna (either stock rubber ducky or my outside) is hooked up. Doesn't happen when you hook up normal headphones nor coming out of the speaker.

I use to hook my Pro-94 up the same way with no problems at all. It seems that as soon as either antenna connection touches anywhere on the antenna hook up on the scanner the buzzing occurs. I've tried several different audio cords to make sure it wasn't a bad cord either, same results.

Edit: This happens even when the scanner is turned off as long as the antenna is plugged in. Happens running on the batteries or the wall plug.

Just wanting to get some opinions on what ya'll might think is causing the problem.

 

[LarrySC]

The scanner does not have a line level signal and does not have a mic. So what are you trying to do??

 

[Scott_PHX_APP]

It sounds like you have an AC grounding problem. In addition to that, I'm not sure, but are you using the speaker out/headphone jack to go into the mic jack on your PC? If so, you need to isolate that connection, or at least you should. The mic input is high impedance and you may be over driving the input really bad with the 97. Not sure what the difference might be between the radios, but I wouldn't drive the mic jack with a speaker output. The line input is somewhat lower impedance but the speaker output is still higher and should be isolated also. Some more info from you as to the humming sound, does it sound like 60Hz or something different? If you touch the cable when it's plugged into the PC, do you still get the hum?
OK, now for the joke part. Try teaching the PC to sing instead of hum?
Later...

 

[kicktd]

LarrySC - I hook the Pro-97 up to my computers line-in to record/listen to it through my computer. Not hooking a mic up to the scanner.

lol I tried to teach it but it didn't work out too well

I'm hooking it into the Line-in not mic, just tested that to make sure it wasn't the line-in jack. Yes it is 60Hz and does happen when touching the jack.

how would you go about isolating it?

 

[pro92b]

Everything you said points to a bad connection from the ground side of the line in jack to the motherboard inside the PC. Isolation is not necessary with the kind of connection you are trying to make and it will not help. If the hum occurs when nothing is plugged into the line in jack and you touch the line in jack, it points to a bad ground in the PC itself.

 

[kicktd]

Hmm ok thanks. I'll have to look to see if my PC is grounding correctly. Good thing I build my own computers lol.

 

[Russell]

Try muting the input you're NOT using through the audio control panel. If you're using line then mute MIC input, etc.

 

[kicktd]

Try muting the input you're NOT using through the audio control panel. If you're using line then mute MIC input, etc.

mic is always muted and I only unmute the line-in when I want to listen to it live. The buzzing is also when recording so most likely like stated above it's probably a ground problem with my motherboard.

 

[Scott_PHX_APP]

Make sure, if you are building your own PC's, that you run ANY audio cableing away from the uP and FAN'S! Yep, fans can be a pain in the ear too. Anyway, as was mentioned, make sure you ground your motherboard and have a good ground from the power supply to the wall outlet, etc. Picking up hum from the cable is common and when holding on to the wire, it's way more common. Good grounding and shielded cables should help for sure. Let us know how it goes...
Later...

 

[n2deep]

I don't know if this is like the same problem your are having, but I use to get a lot of humming and feedback when I had the Pro 97 plugged into the external power either at home or in the car and used the headphone jack to hook up to my computer or external speaker, but I used a Paper clip with one end wrapped around the antenna and it solved the problem. I have been using it like this for over a year now. Look at the attached picture...Hope this helps

http://jms1974.googlepages.com/Pro97.JPG

 

[Scott_PHX_APP]

OH! they must have done the same thing on the 97 as the 95 with the 100 ohm resistor in series with the earphone/external jack ground. That's a pain in the ^#@$ if you ask me, but I'm sure they are just trying to cover theres. That may be why you're getting the hum on the 97 and not the other. I use to have the clip on my 95 but got tired of the BNC getting jamed and sometimes getting a bad connection to the ear phone now and then, so I solved the problem for good. I just soldered a 50uF cap from the jack ground to the chassis/antenna ground and it's done... I never thought of that as a reason for the noise. If I remember right, it's a 100 ohm resistor in series to "protect" you from hurting your ear if you have the level up to high. The problem I always had was when I turned up the volume to hear in the earphone, the sound was distorted too much. Bad Radio Shack, Bad, Bad, Bad...
Later...

 

[Halfpint]

Bad Radio Shack, Bad, Bad, Bad...

Actually it should be Bad lawyers, Bad, Bad, Bad... Either someone's kid managed to completely blow out their hearing or there have been enough `gummit' funded researches finally done that *prove* that stupidity when it comes to cranking up the volume to `Rave' levels will do so and instead of making an example of them for their stupidity the nannies went and sicced their lawyers on the various companies that make equipment with headphone jacks and either collected a whole wad of $$$ or convinced them that they would if they didn't do something to protect the idiots from themselves. The really horrible thing is that even when `the proper precautions' are taken to protect oneself from excessively louds sounds all it takes is for just a few to `sneak through' and one's hearing can be destroyed forever. Doing stuff like putting that type of limiting that one finds in those scanners *isn't* going to do a danged thing *except* introduce other problems like what we are discussing or even worse provide a false sense of security. (And the lawyers will just find something else to sue or threaten to sue about.)

Just a disgruntled `Olde Fart's' 2¢ worth. {FROWN!}

 

[kicktd]

I'm off to find a paper clip! Since everything in the computer is grounded properly lol

Edit: haha That worked! Took a little position of the clip but I got it. Sounds SO much better now without that buzzing. Thank you n2deep!!