Ummm ... on my K3 [#642 but upgraded by Elecraft and with new synth],
the noise level decreases as I narrow the BW, pretty much just like
information theory says it should. On the other hand, a CW signal
centered in the passband doesn't change much if at all. I'm pretty sure
that's how it's supposed to work. I can detect a tiny decrease in the
signal level but it is just discernable, nothing big or a problem.
I normally run CW in contests at 250 Hz, sometimes 200 Hz, I have used
100 Hz occasionally when necessary. I don't think I've ever used 50 Hz,
CW sidebands at 30 WPM exceed that and the code elements start to run
together from ISI.
73,
Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org
On 9/13/2015 7:41 PM, Keith Onishi wrote:
One of my friend K3 users report that AF output level with 100Hz
passband width is lower than with 150Hz passband width. He also
reported that a noise like “Ptsu” was generated on reducing passband
width from 150Hz to 100Hz. He had guessed that these were specific to
his K3, but some other K3 users including myself reported the same.
Some extreme users who use this narrow passband may have been
bothered by this reduced AF output level and noise. If the AF output
level change is caused by K3 DSP filter design or program, adding
automatic gain compensation feature to keep same AF output level
would be highly welcome.
73 de JH3SIF, Keith
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