I have a kt8900d mobile radio being used as a base and am looking for a good external speaker for it. I tried a ts750 speaker which i purchased from amazon but no volume comes out even with the radio turned up. Any suggestions? The first speaker i tried was a small uniden scanner speaker but all it did was keyed the radio up when plugged in.
Your issue lies with the wiring of the jack on the back of the radio. The jack is a "TRRS" four conductor configuration because, in addition, to having audio out it also carries microphone in and PTT. Plugging in a standard two conductor mono speaker either isn't making contact with the speaker connections or shorting the PTT, throwing the radio into transmit.
The solution is probably going to be wiring a plug correctly yourself.
(See page 4 of the manual.)
