Batboard

My audio on my TK-790, ONLY IN SCAN MODE, the speaker has a background hissing sound. When it stops on an active channel it is loud and clear. When i plug my antenna into the antenna jack the hissing gets louder. i put a noise filter (ground loop isolator) on the speaker cable and the hissing has stopped but now the audio is so low you can barely hear it. Take the noise filter off and and the audio is back loud and clear but the hissing is also back.

thanks

asmitty0010 wrote:My audio on my TK-790, ONLY IN SCAN MODE, the speaker has a background hissing sound. When it stops on an active channel it is loud and clear. When i plug my antenna into the antenna jack the hissing gets louder. i put a noise filter (ground loop isolator) on the speaker cable and the hissing has stopped but now the audio is so low you can barely hear it. Take the noise filter off and and the audio is back loud and clear but the hissing is also back.

thanks

Just curious, have you tried a Kenwood board, they may be more familiar with the issue being is how that is their radio of choice.

Without having a schematic to look at, I would guess a mute gate is not clamping the audio to the PA well enough during scan to fully eliminate the normal squelch noise on an unbusy channel. This may be normal. I would have to hear how loud the residual sound is. The advise to talk with other Kenwood users is your best first step.