Pro197 speaker acting as an open mic on feed???

Ok this one is very odd - and kind of disturbing.. I just found out by accident that my feed may or may not have been picking up "open mic" noise, even though there is no microphone installed on the computer (and no, it doesn't have one built in or a webcam hooked up, this is a dedicated, home built machine in a rack in a closet). I had my android app running while I was messing around in my server closet, and all of a sudden I heard the sounds of a screwdriver Plinko-ing through the rack (which had happened 30 seconds earlier) coming over the app!!

I brought up the streamer program to the VU meters and started tapping around, and found that it picks up strongest when I tap directly on the scanner itself, and I can hear myself when I talk toward the speaker!!! So like, WTF?! I know some people have complained about hearing open mic stuff on other feeds, and thats why I was careful in my own setup.. But this is maybe something everyone should check on - make sure they aren't broadcasting open mic inadvertently...

It happens regardless if the feed is plugged into the headphone or EXT jack, and it is most definitely coming into the computer via the Line In, and only on the left channel (right channel is a BC72XLT which does not seem to have this issue).. If nobody has any other suggestions as to why it's doing it or how to stop it, I'm going to open it up and disconnect the speaker.. This also showed me that what I thought was ground loop hum is actually fan noise from the network equipment and servers.

I have actually contacted a different feed provider before for this exact same issue (unknown feed scanner model). I heard what sounded like an open mic and immediately contacted the feed provider about the issue. He told me that he didn't know of a microphone that was attached to his feed computer and didn't know why it sounded like a microphone on the feed. He was able to reset it, but at some point it came back and I had to contact him again about it. The feed has since been discontinued (unknown if it was related to the issue), but it certainly is a pretty nerve-racking situation to be in if you aren't constantly vigilant of what your feed is actually broadcasting.

Same problem here

I have a radio shack pro-197 scanner also and it is doing the same thing, however i have already taken it apart and luckily the speaker is plugged into the board rather than soldered so i thought easy fix and unplugged the speaker, guess what its still broadcasting open mic I have no clue, i have completely torn this scanner apart looking for another speaker or a hidden microphone to no avail. what did radio shack do when building this scanner? how is it possible the scanner is acting as open mic? the replies i have received on my post ask about mics hooked to computer etc which I do not have any, also like you this is a dedicated machine, at this point I am lost on what is causing the open mic and I am kinda freaked out that if I am talking loudly people can hear my voice on my live feed. If you solve this problem please let me know. Regards,

John Howell

here is my post http://forums.radioreference.com/radio-shack-scanners/301115-very-strange-problem.html

There is reason for this and I can't for the life of me remember what it is. Someone will be along to tell us what it is. Do not destroy your radios, it is a easy fix. This has happened before and has been posted before.

I have a PRO-197 and have also heard this happen. I actually have not tested this much but I placed a towel under the scanner to isolate it from the desk it is on. I will do some more testing this week, but I think it helped.

Bob

A speaker is a mic and a mic is a speaker. Cheap intercoms usually use the speaker as both a speaker and a microphone. I don't know why the scanner's speaker isn't disconnected when you plug in the audio feed to your computer. Maybe a bad jack on the scanner?

jackj said:

A speaker is a mic and a mic is a speaker. Cheap intercoms usually use the speaker as both a speaker and a microphone. I don't know why the scanner's speaker isn't disconnected when you plug in the audio feed to your computer. Maybe a bad jack on the scanner?

Click to expand...

The speaker is unhooked, so this has to be something else

jhowelljr said:

The speaker is unhooked, so this has to be something else

Click to expand...

If you kill the power to the scanner all together, do you still get the live audio over the feed? If so, you should probably start looking in a different direction, like your computer. If it goes away, then the scanner is a good place to look.

In the old days, the VCO of the scanners were very sensitive to any component vibrations. If you opened up the old scanners, you would find the VCO sections were covered with wax. This removed the vibration problem of the scanner being sensitive to component vibrations and the micro phonics went away. There is always the possibility that the vendors have taken shortcuts and this is the results.

One way of trouble shooting this if you are certain it is coming from the scanner is to take the covers off. Then take an insulated object like a straw or one of the cooks wooden spoons and start lightly tapping different areas of the scanner and see if you can find the sensitive spot or component that seems to have the strongest results. Coils and capacitors in the VCO area of the scanner would be my thoughts.

jim202 said:

If you kill the power to the scanner all together, do you still get the live audio over the feed? If so, you should probably start looking in a different direction, like your computer. If it goes away, then the scanner is a good place to look.

In the old days, the VCO of the scanners were very sensitive to any component vibrations. If you opened up the old scanners, you would find the VCO sections were covered with wax. This removed the vibration problem of the scanner being sensitive to component vibrations and the micro phonics went away. There is always the possibility that the vendors have taken shortcuts and this is the results.

One way of trouble shooting this if you are certain it is coming from the scanner is to take the covers off. Then take an insulated object like a straw or one of the cooks wooden spoons and start lightly tapping different areas of the scanner and see if you can find the sensitive spot or component that seems to have the strongest results. Coils and capacitors in the VCO area of the scanner would be my thoughts.

Click to expand...

Yes it is certainly the scanner I have conducted hours of testing and have isolated it to something (some component) contained within the shielded metal box on the board where the antenna connects to the back of the scanner. however this shielded box is both glued and soldered to the board and not being a board level technician this is where I have to stop, so I will be taking the scanner to my local ham radio club to a gentleman who is qualified at board level to further investigate.

PRO-197

I also have the open mic problem on my Pro-197. If I whistle loud enough I can hear it in my external speaker. Also if you tap the over it gets really loud over the external speaker. I opened it up and disconnected the internal speaker thinking that might be the problem but it is still acting as if it has a mic built in. I did not see one in side when I had the cover open.

Any body figured this one out yet?

Jamie R. Dean - WX4PUP