[ARC5] Perhaps an error?

[Jim Wiley]

Use a scope to observe the RF envelope.  Assume for this example that 
you have set the scope so it shows 2 cm of vertical deflection above nd 
below the center line (4 cm total).  50% modulation will show peaks 
rising to 3 cm and dipping to 1 cm on either side of center line. This 
can serve as a calibration point from which you can observe what the 
meter on the 8640 says.  Does it agree at the 50% point?  10% modulation 
would have the trace rising to 2X the quiescent level, or 4 cm on each 
side of the center line, and dipping to exactly the center line.  Most 
8640 generators I have seen can do this,  and in fact can actually 
exceed 100%.

- Jim, KL7CC


On 6/13/2013 4:21 PM, Kenneth G. Gordon wrote:
> On the HP-8640B, how do you make certain that modulation percentage 
> for AM is 30%? Which scale does one read? I now suspect that the AM 
> modulation percentage was not 30% but something significantly 
> higher...like maybe even 100%, although I have never yet known of a 
> signal generator which could modulate 100% in AM. Anyone? Ken W7EKB