[Elecraft] APF For K3

[Paul Christensen]

> I found the APF in my Icom 7800 worthless.

Same here.  Icom's implementation of APF in the '7700/'7800 is really an 
"Audio Passband Filter" with low Q.  It's really no different than narrowing 
a DSP passband filter.

What's unique about the FT-1000D's APF is that the Q is very high, although 
its affected with APF tuning.  The high Q of the circuit forms a very narrow 
filter with fixed gain, and variable peaking frequency.

Paul, W9AC