Don Wilhelm wrote:
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.
True enough -- but if you are a SW DXer trying to verify the ID of a weak,
rare SWBC station, and therefore not particularly interested in fidelity, you
can listen to AM in USB/LSB mode quite satisfactorily by zero-beating the
carrier. This is especially cool because by switching between LSB and USB, you
can pick the sideband that is the least interfered with by adjacent-channel
signals. Having chosen the sideband to listen to, you can then tailor the DSP
passband to maximize intelligibility. I use this mode often when DXing on
broadbanded GC receivers in preference to using the wide AM mode provided.
Bill / W5WVO
K3 in February 2008
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
[EMAIL PROTECTED] 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
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