Request To Uniden Regarding External Speaker Connection 996/536

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Jan 22, 2003
McLean, VA
This is a request to Uniden for direction, guidance, diagrams, Technical Bulletins or Uniden supplied Accessory cables/adapters to deal with the External Speaker issue on the 996/536 and maybe other similar design Uniden scanners.

External Speaker Issue: The External Speaker connection/amplifier/design needs to be isolated from anything other than a passive External Speaker. Using an amplified External Speaker, Mixer, Recorder or external device that has power can cause ground loops, hum, reduction of output, muffled sound and possible in worst case situations even damage to either the scanner or other connected device.

I think it is fair to say that there are more and more issues coming up with the External Speaker output questions and problems from end users on these scanners due to the audio output amplifier design.

For example a was experimenting with my 996XT yesterday with an AC Voltmeter between the chassis ground and the External Speaker ground/sleeve. When I plugged headphones into the front headphone jack of the 996XT, the AC potential between the chassis ground and External Speaker ground/sleeve, the AC Voltage jumped from milliVolts to Volts. Is this specifically a problem?? I am not sure, I was just playing around as I am getting ready to interface some Motororla amplified speakers and I wanted to make sure there will be no problem with ground loops or Voltage feedback. I need to look into this futher before I integrate my amplified speaker.

I am looking to Uniden, the designers and experts of this hardware, to document what is going on with these External Speaker outputs and provide specific circuit interface diagrams, cable build examples/recommendations/schematics, suggest appropriate ground loop isolators or coupling transformers with part numbers and sources and/or actually offer Uniden designed Accessory cables or Interfaces that will work properly and protect the scanner and attached devices.

Uniden, thanks in advance for considering this issue and offering the user community a consistent and functional solution.
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