[Elecraft] K3 Filter advice...

[Don Wilhelm]

Drew,

For AM you will need either the 6 kHz or the 15 kHz filter - an AM 
signal will not fit through the 2.7 kHz filter without seriously 
degrading the fidelity.

The 2.7 kHz filter along with the DSP filtering does an acceptable job 
for casual CW, but if a strong (S-9+30) station comes on the air within 
that 2.7 kHz bandpass, the DSP input can be overloaded, so you may want 
to consider a filter more narrow than the 2.7 - I think 500 Hz is a good 
choice.  For data modes, 200 Hz is a good choice, and IMHO is a bit 
narrow for normal CW.

If you are into operating during periods of heavy band use (like contest 
times), then the 8 pole filters with their steeper skirts may be 
helpful, but for more casual use, the 5 pole filters do a great job.

Remember that the filters are 'roofing filters', and not the final 
filtering (which is done in DSP).  Their purpose is to reduce the 
strength of undesired signals ahead of the DSP ADC - as long as the DAC 
is not overloaded, the DSP can provide all the filtering needed.  Right 
now, I have only the 2.7 kHz filter in my K3 and it does quite well on 
CW with only the DSP filtering - but then I have not operated on a 
contest weekend yet either.

73,
Don W3FPR

drewko1 at verizon.net wrote:
> I'm wondering what minimum complement of filters would work for me in
> a K3. I am only interested in general coverage reception of SWBC
> stations, plus operating CW. I am a little unlclear about what filter
> would be required for AM (reception only), with the KBPF3 option.
>
> For CW I generally prefer a wide filter (my K2 is set at 2.0 kHz most
> of the time). I suppose I would want a narrower filter as well but
> can't decide whether 500/400 or 250/200. 
>
> Does a 2.1 kHz + 200 Hz filter pair seem like a useful combo for CW?
>
> Finally, I don't have a clue what noticeable difference there would be
> between a 200/5-pole and a 250/8-pole. If the difference is really
> subtle or limited to very occasional use I suppose I'd go for the
> cheaper one. 
>
> 73,
> Drew
> AF2Z
>
>