Line level audio into Flex 6400 .. audio extremely hot by the time radio modulates 100%

Kevin J. Darrah

I run AM exclusively with my Flex 6400. Through the Mic input all seems well for the most part. I decided to run audio into the 15 Pin Connector. Now I am extremely puzzled. 

As long as I keep the modulation levels somewhere between 50% and 75% the audio is satisfactory.. When I try to modulate the audio too 100% as verified with a scope the audio is so excessively hot, even before the leveler encroaches 0 DB.... 

There is no hum, no anomalies etc.... On the audio .... AS long as I keep it at 50% ....  Wondered if anyone else had noticed/tried this on AM and had similar results. 

Kind of a strange situation, thanks. 

Bill -VA3WTB

Are wiring your mic directly to the 15 pin connector? or using a small mixer?

Rod KQ6F

I also have a 6400.

I hooked up an audio oscillator to pins 1 and 2 on the ACC connector, selected ACC input, AM mode and watched the RF envelope on a scope as I cranked up the oscillator output.  Everything perfect from zero to 100% modulation - no erratic behavior.

Kevin J. Darrah

Using an Omnia Volt.... running that into an attenuator to bring it down to consumer level audio, then a 600 ohm audio xmfr .... Using pins 1 and pin 10 on the connector into the Flex. 

Kevin J. Darrah

I thought pin #2 was for powered speakers... I will have to check that out, thanks

Rod KQ6F

I fed the audio into pins 1 and 5.  Pin 2 was a typo.