[Elecraft] [K3] what audio passband should I expect in TX DATA/DATA A mode?

[Pierfrancesco Caci]

>>>>> "Matt" == Matt Zilmer <mzilmer at roadrunner.com> writes:


    Matt> Hi Pf,
    Matt> Most tone modes operate at an offset from carrier frequency, so that
    Matt> the audio frequencies of interest are more or less cenetered in the
    Matt> filter passband.  I believe the JTx modes are already in the 1200 to
    Matt> 1500 Hz range so no offset is required.

Hi Matt,
actually, I'm seeing JT9 stations transmitting at 3400 Hz, and who knows
if there are some even above that. JT65+JT9 uses quite a wide receive
window. 


    Matt> The crystal filter being used only restricts the bandwidth of the RX
    Matt> chain (1st IF).  The DSP imposes its own audio filtering on the
    Matt> baseband, and that's what you're seeing as rolloff below ~300 and
    Matt> above ~3500 Hz.

Yes, and that was what I wanted to know. I've read in this mailing list
that the DSP limits the audio at 4 kHz. I'm seeing it roll off at little
above 3400. The low end rolls off at around 300, so I'm getting an audio
passband of ~3100 Hz. I wonder if this is normal, or if there's
something else I can tweak in the settings. 


Pf

-- 
Pierfrancesco Caci, ik5pvx