Yes you must turn off the agc. Then the audio output will be linear
with respect to incoming signal strength. You will probably have to
adjust the rf gain to avoid overloading the receiver with the agc off.
Once a reference level is set then you can compare the two antennas
difference.

73
Gary K4FMX

On Fri, 15 Apr 2005 20:30:08 -0500, "Ken Bessler"
wrote:

I'm trying to evaluate incoming signal strength
using my soundcard and a program called
"Cool Edit Pro 2.1". This rather sophisticated
package allows measurments down to 0.001
db.

I was wondering should I turn off my AGC on
my FT-857D for these measurements?

I take 10 readings within 1 second then switch
antennas and repeat. I average out the readings
and then decide which antenna is best for that
signal. I also look at background noise levels as
a reference.