[Elecraft] K3 CW Reception
Steve Walter WA3A
wa3a at arrl.net
Sun Nov 1 15:58:56 EST 2009
Now that I have my first receiver that actually hears whats on the band (K3
of course) I am in need of some education on cw reception. I have K3 #3397
with 2.7, 1.8 and 400 hz filters. Latest beta.
When tuning away from a cw signal and the tone disappears I continue to hear
clicking (not quite clicking but more like cw with no tone) for up to
another 500 hz. Usually more like 250-300 hz. I normally use the 400 hz
filter. Reducing rx bandwidth begins to help around 100 hz but its still
noticeable. I believe this is caused by the transmitted cw waveform and the
rise and fall times. My understanding is that this is also what causes key
clicks but I'm not sure if thats what I'm hearing. To me, key clicks would
extend further from the center than what I'm hearing. Is this what also
causes faster cw to use more bandwidth? It is on all cw signals and not
related to strength (although its usually wider with a stronger signal) or
AGC settings (including off). Of course, on steady carriers I dont hear
anything once the tone is gone. When listening to a TS570 its not nearly as
noticeable BUT there are alot of other things going on like AGC pumping and
images and just mushy audio in general. Its amazing to me how bad the 570
sounds after using the K3.
Another part to this question: What does transmitted phase noise sound like
on reception? I have read a lot of posts on phase noise but I have no idea
what people are hearing.
And maybe on a related topic I have also noticed SSB splatter much more with
the K3. Is this also related to the K3 just being a cleaner receiver?
None of these issues seem to be rx overload. I dont use NB, NR and always
use the ATT on the lower bands. As I said before I have tried various AGC
settings including agc off and backing off the rf gain with no real
difference.
Maybe I'm just now realizing what alot of you have been talking about...
Poorly designed and/or improperly operated transmitters/amplifiers. If
thats the case its an eye(ear)-opener for me!
73, Steve WA3A
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