Microphone level for Flex 6400... Use little square or solid line as reference for not cresting 0 DB

Kevin J. Darrah

Ok here goes.... I operate AM most of the time. With my Flex 6400, should I be adjusting my Leveler with the little Square that travels ahead of my solid line so that it doesn't strike 0 DB, or, adjust my Mic level so that the solid line travels no more then a couple of DB from 0 on the mic level meter. 

The reason I ask, if I adjust everything properly, then adjust my Mic Gain so that the little square ahead of the solid yellow line strikes the 0 DB limit... I have a 10 watt carrier and it's modulating too 20 watts on a peak reading watt meter, which is only 50% modulation. 


If I adjust the leveler so that the little square bottoms out at 0 DB, then adjust so the line is solid and just cresting past -10 and start turning yellow, then I have what would be 40 watts showing not only on the meter of the Flex 6400, but also I have 100% modulation according to my peak reading Watt Meters, which is an LP 100 BTW, so it's not a cheap ill-calibrated meter. 


It just seems as if there's a huge gap between the solid line, and the floating square that strikes the 0 DB mark, almost prematurely it seems. 


Any input on how this level meter is correctly adjusted from you users? Adjust to where the square hits the 0 DB mark first, or, adjust the mic gain up further so that the leveler is actually a solid line and stop it within a few DB of 0?

Bill -VA3WTB

The little dot ahead of the solid line is the audio peaks. Set your audio so the peaks  never reaches the red 0,,Best place is about -5.

It has been discovered that the EQ settings could send the peaks into the red but it is not being shown on the meter. That is a discussion for another time. It has been found that setting EQ sliders below the 0 mark gives the best audio as it won't drive the audio input to hard.

Kevin J. Darrah

Ok thanks.... well this limits my Flex 6400 to 50% modulation on AM then, that's all I wondered. I can see at this point the Flex was a poor choice to use for AM. Thank you and have a great rest of your week! 

Bill -VA3WTB

It is really a great choice for am. You will find when setting your audio properly that will give you all the drive you need. Many of us use AM a with great reports, no reason why you can't.

Kevin J. Darrah

If I adjust it the way you have specified, it only yields 50% modulation, according to the meters and the Oscilloscope. There really is no other method of adjustment, and the EQ levels were kept below 0... I always take away before adding too when EQ'ing. Thanks, I was hoping I was reading the leveler wrong, but such is not the case. I have 30 days to send it back, so I'm not out anything. Thanks again. 

Bill -VA3WTB

what you can do s to go on the air and talk with a friend while adjusting the audio and see where it works the best? As I said many use the Flex for AM,,so it must be fine,,I think you selling a little short.

Kevin J. Darrah

if you run AM, then you understand that 4x the carrier is 100% modulation which is how you correctly operate AM. On a 10 watt carrier that would be 40 watts PEP out of the radio, not 20 watts. I've been on AM for nearly 40 years, the mechanics don't change because it's suddenly being done with an SDR. Perhaps there is something wrong with the unit, but it will not work the way it is currently functioning unfortunately.