[Elecraft] K2 filter attenuation

[Ron D'Eau Claire]

I've noticed that when trying to grab a weak signal I have to keep the
filter wide. If I try to narrow the filter selection to block out an
adjacent signal there seems to be some (significant) attenuation to the
filter. ...
Colin
N=D8YGY
----------------------------

Is it really attenuation, Colin? Sometimes I can read a very weak signal
better at wider bandwidths, even with some QRM. That's because of what
he filter does to the background noise.=20

When the band noise encounters a narrow filter, individual spikes of
noise get stretched out - made broader. That's a normal consequence of
any filter and it shows up dramatically in a narrow filter. It also
happens to the signal itself on the on/off transitions at the end of
each dit and dah. That makes the transitions at the end of every dit and
dah less clear. The combination can make a weak signal much harder to
copy at a narrow bandwidth and it is with a wider bandwidth.=20

The total effect is to make the signal sound weaker in relation to the
noise and, unless he is sending quite slowly, makes the CW a little
harder to copy even without the extra noise because the code element
spacing has been shortened and less distinct. =20

Ron AC7AC
K2 # 1289