[Elecraft] K3 Rev C DSP with Low Freq Enhancement

Wayne Burdick n6kr at elecraft.com
Tue Oct 13 13:31:45 EDT 2009


I believe the add-on LPF module for the DSP board will be available  
soon. We'll post details at that time. It's easy to install.

The rolloff of this module is 4.5 kHz, and it completely eliminates  
all high-frequency artifacts resulting from the CODEC's 12-kHz sample  
rate.

I can't hear the artifacts, which are typically 60 dB down from even  
weak audio signals, but some operators with better ears apparently can.

73,
Wayne
N6KR

On Oct 13, 2009, at 12:37 AM, Eric Tichansky wrote:

> Paul Christensen wrote:
>> Take a look at what's happening before the ADC and after the DAC  
>> circuits.
>> The K3 has some of the best designed audio circuits for a  
>> communications
>> transceiver.
>>
>> Paul, W9AC
>>
>>
> Unfortunately, the issue with the 12 kHz leakage (DAC clock?) and beat
> notes (+/- CW sidetone around 12 kHz) make for some awful audio in CW.
> I guess most folks don't hear it, but given previous reports from
> others, it is an issue.  I can't comfortably use the K3 for CW unless
> using outboard low-pass audio filters to knock the high end garbage  
> down
> to an in-audible level.
>
> 73
> Eric NO3M
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