Odd Behavior - SDS200 Goes Deaf On External Speaker When Plugging in USB Cable

[vannossc]

I have a BHI external noise-cancelling speaker plugged into my SDS200. Works perfectly until I plug in the USB cable connected to my PC (fanless Kamrui) in order to run ProScan. As soon as the outer metal edge touches the outer connecter (not inserted yet!) the external speaker goes deaf. Remove it - works fine. If I unplug the speaker, the internal speaker works just fine with the USB cable plugged or unplugged..

Not optimal as I'd like to leave both plugged in at the same time.

Thanks for any insights,

Scott

 

[tvengr]

The audio output jack floats on the SDS200. It is not corrected to ground. When you touch the USB cable, you are shorting out the audio output. The Uniden BC23A external amplified speaker has an audio isolation transformer built in to avoid problems like that. Your speaker should have a stereo plug. A mono plug shorts out half of the audio amp in the scanner and can damage the amp. It is a balanced output on the scanner using the tip and ring connections.

 

[iMONITOR]

The audio output jack floats on the SDS200. It is not corrected to ground. When you touch the USB cable, you are shorting out the audio output. The Uniden BC23A external amplified speaker has an audio isolation transformer built in to avoid problems like that. Your speaker should have a stereo plug. A mono plug shorts out half of the audio amp in the scanner and can damage the amp. It is a balanced output on the scanner using the tip and ring connections.

All my external speakers have a monaural plug and I have them connected to both of my SDS200's, and using USB cables have no problem of any kind.

 

[mc48]

Try a ground loop isolator on the speaker cable if you have one.

 

[tvengr]

All my external speakers have a monaural plug and I have them connected to both of my SDS200's,

If they are non-amplified and a speaker terminal does not have a connection to ground, you will not notice the problem.

 

[vannossc]

Understood. Yes, this speaker has a mono 1/8" plug that is permanently connected to the powered speaker.

It's this speaker:

https://bhi-ltd.com/images/docs/manuals/DSPKR_User_Manual.pdf

I'll look for an isolator and give it a try. I like the external speaker as if fires forward and does a good job with the audio. Not fatal if I need to unplug it for a while - just inconvenient.

 

[doctordialtone]

I'll look for an isolator and give it a try.

I use these.

They're cheap and work great!

 

[vannossc]

I use these.

They're cheap and work great!

It's on the way. Will report out results.

 

[doctordialtone]

It's on the way

Great!

One more benefit of the Ground Loop Isolator is that it will remove any "popping" sound in the audio when using amplified speakers.

Let us know how it works out.

 

[vannossc]

Tried it just now - does not work on the rear jack at all. Works on the front jack but pops like crazy. Nothing good so far. This BHI speaker works good but not worth the trouble it seems.

 

[tvengr]

his BHI speaker works good but not worth the trouble it seems.

Try the Uniden BC23A speaker. It also has noise reduction (switchable in and out) and a volume control. It has a stereo plug to avoid shorting the output. It also has a built-in isolation transformer. You do not need any isolators. It plugs directly into the external speaker output jack of the scanner. (Note: The BC23A uses only the tip and sleeve connections on the plug).

 

[Trucker700]

Try the Uniden BC23A speaker. It also has noise reduction (switchable in and out) and a volume control. It has a stereo plug to avoid shorting the output. It also has a built-in isolation transformer. You do not need any isolators. It plugs directly into the external speaker output jack of the scanner. (Note: The BC23A uses only the tip and sleeve connections on the plug).

I used the BC23A with my SDS100 in an 18 wheeler for several years. Worked great. The internal speaker in the SDS100 just didn't have the power to overcome the noise from the Cat diesel engine. The powered Uniden speaker made a huge difference.
James

 

[gmclam]

I am running an SDS-100 powered from USB / cigarette lighter adapter and connected to powered speaker w/o issues. It does matter where power comes from for the radio and the speaker.

 

[vannossc]

I have an Yaesu FP-1023A power supply attached to a West Mountain power pole distribution box. Power to the scanner and speaker come from that supply - no wall warts involved. The power supply is grounded to a copper grounding bar station which is grounded to ground (8ft copper grounding bar).

I wonder if I made my own problem now...ground loop