[Elecraft] Data mode and filters

[Jim Brown]

On Sun,5/17/2015 7:29 PM, Joe Subich, W4TV wrote:
> Yes, you were probably over driving the K3 (KPA3).  You can estimate
> the amount of overdrive by using the the LP-100A Peak to Average
> function.  With PSK31 "idle", the LP-100A shows the following: 

Perhaps, BUT -- look at the data for 100W, 93W, 50W. and 29W. The 100W 
and 93W data clearly shows IMD at levels corresponding to 2-tone data, 
the difference between 100W and 93W is 4 dB, and at 50W almost no IMD is 
visible (there are sidebands +/- 360 Hz 60 dB down). 50W gets a legal 
limit amp to full power. At 30W, which gets the KPA500 to full power, 
sidebands at about +/- 50 Hz are barely visible, there are -63 dBc 
sidebands at about +/- 360 Hz.

But let's return to the real world issue -- QRM as the result of 
excessive occupied bandwidth. The K3 I measured is 105 Hz wide at -40 
dBC at 29W, 110 Hz at 50W. At -60 dBC, it's 340 Hz at 29W and 720 Hz at 
50W.

Given that the vast majority of PSK31 ops work below 50W and that 50W to 
a power amp will get you to 1500W, your concerns simply do not make 
sense in the real world.

73, Jim K9YC