[Elecraft] [K3] Width Control and AF Output Level

[Fred Jensen]

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