Loss of audio when amplifier is moved to operate

WV5Q

I have a 6400M that works perfectly. I have an Ameritron ALS-600 that I would like to use. When I turn the amplifier on, everything is normal, but when I switch to operate, I lose all audio on the radio. I am using an ARB-704 relay interface. I have gone over the manual, and all settings on the radio are exactly as the manual shows. Ideas?

KD0RC

What cables do you have plugged in between the 6400M and the ARB-704? Especially, what do you have the ARB704 Radio jack connected to?

WV5Q

TX1 RCA to interface, Relay out of interface to amplifier. TX1 checked on TX Band Settings.

KD0RC

If you unplug the TX1 cable, does receive work again? I am wondering if the polarity of either TX1 or a jumper in the 704 is set wrong.

Mike-VA3MW

You don't really need the 704, so you are safe to do what Len suggests and I would test without it.

WV5Q

Mike and Len (et al), That did it. Took the 704 and the associated cables out, only radio and amp connected with Coax. Perfect. All works FB now. Thanks.

WV5Q

I have received a couple of replies to my initial question and problem of, as soon as I switch the ALS to operate I lose all audio on the Flex. I have the RCA plugs to the Relay on the 600 and TX1 (turned on in TX menu). The ALC doesn't seem to cause a problem. I have also had the ALS 704 in line and that doesn't seem to make any difference. I am missing something here. Any suggestions? And to Len, as soon as I put the 600 back in standby I again have audio.