[Elecraft] APF for K1, K2 and other rigs -

[Ron D'Eau Claire]

I'm one of those who has been testing the K3 APF implementation. 

 

As I mentioned earlier, it reminds me of the analog tunable active filters
I've used beginning with a vacuum-tube "Select-O-Ject" back in the 1950's
and right up to the little Elecraft AF1 Audio Filter mini-module kit.

 

So I dug out the AF-1 and hooked it to the K3 phones output, tuned in some
stations and switched between the outboard AF1 and the Elecraft APF. 

 

I find very little difference in the sound. The AF1 provides the peaking
gain with a shape peak and wide skirts and in BP2 position has a very
similar sounding bandpass characteristic to the APF. In addition the AF1
offers an optional lower Q filter in BP1 position of its selector switch,
plus a separately variable low pass filter to roll off the high frequencies
as you wish.. 

 

So, if you've got a K1, KX1, K2 or other rig and want to see what the
"hoopla" is all about try an AF1 on your phones output.  

 

(And for you frustrated solder jockeys it'll give you an excuse to dig out
the old iron and melt solder :-) 

 

73, 

 

Ron AC7AC