If an external speaker is plugged into the 3.5 mm port in the back, can you still hear sound from the speaker on the scanner? I want to use an external speaker in my garage but also have sound at the scanner.
There's a mechanical swith in the jack that breaks the connection to the internal speaker.
You could open up the scanner and solder a wire to the jack so it will never break that connection,
or try inserting the plug gently until you feel a resistance, then the switch never engage and the tip of the plug makes a connection in parallell with the inner speaker.
If you use the LINE OUT and set all channels to RECORD and run it to an old stereo with AUX in you have a vol control in the shop and you do not change the impedence of the scanner audio amp.