[Elecraft] Which Audio Filter Kit?

[Bill Coleman]

On Feb 6, 2005, at 6:57 PM, Jim Harris wrote:

> Hopefully, I'm about two and a half weeks from
> ordering a K2 with about four accessory kits.  My
> question today is how much difference is there in
> performance between the KDSP2 and the KAF2?  Is the
> KDSP2 worth the extra $140?  I'm been using an
> IC-746pro for about a year and a half so I am familiar
> with the use of a DSP.

I've had both in my K2. Here are my impressions.

I wasn't thrilled with the KAF2. The CW filters in the K2 are sharp 
enough that I never needed to "supplement" it with an audio filter. I 
also found that the narrow audio filter sounded a little bit too 
"ringy" for my tastes.

I did, however, make use of the real-time clock in the KAF2 on 
occassion. Setting it was a pain, though. I also appreciated how much 
high-pitched audio hiss the standard low-pass filter of the KAF2 
removed. It was worth the price just for this feature.

THe KDSP2, on the other hand, has been a boon for me. For SSB, it is 
indispensable. I run the auto-notch all the time in SSB. I use the 
filtering to help clean up the shape of the crystal filter. It also 
helps to have a couple of narrower positions handy on SSB.

On SSB and CW, I haven't found the NR filter to be terribly useful, 
although it sometimes helps. Biggest problem is that it makes it sound 
like you are listening to the band through a long narrow tube.

I'd buy the KDSP2 again. The KAF2 would be OK if you are running 
battery or solar powered and  are concerned with power consumption.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901