New K3 DSP Board

[Roy Morris-6]

If the new DSP board does not improve the low frequency response in receive audio unless the bandpass is adjusted as some have suggested, I wonder what it is intended to do.   Is it supposed to improve the low frequency transmitted audio?  What can the new DSP board do that the TX EQ and RX EQ in the MAIN menu not do?   Roy Morris  W4WFB
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[Bob Cunnings NW8L]

Lyle posted this a while back:

http://www.mail-archive.com/elecraft@.../msg83487.html

describing the changes.

Bob NW8L

On Sat, Jan 23, 2010 at 7:55 AM, Roy Morris <[hidden email]> wrote:

> If the new DSP board does not improve the low frequency response in receive audio unless the bandpass is adjusted as some have suggested, I wonder what it is intended to do.   Is it supposed to improve the low frequency transmitted audio?  What can the new DSP board do that the TX EQ and RX EQ in the MAIN menu not do?   Roy Morris  W4WFB
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[P.B. Christensen]

> "If the new DSP board does not improve the low frequency response in
> receive audio unless the bandpass is adjusted as some have suggested, I
> wonder what it is intended to do.   Is it supposed to improve the low
> frequency transmitted audio?  What can the new DSP board do that the TX EQ
> and RX EQ in the MAIN menu not do?   Roy Morris  W4WFB"

Here's a summary:  The Main DSP Board (Rev. D) does three things that are
independent of EQ settings and contrary to other opinions, do in fact make
measured improvements to Tx and Rx audio response:

1) The new low-pass audio filter in the Rx path attenuates undesirable
artifacts above approximately 4 kHz;

2) The headphone low frequency response is improved when using low Z
headphone types (e.g., older 4 or 8-ohm) through a 10X increase in coupling
capacitor value; and

3) Mic and Line-In low audio response is improved through the re-scaling of
several components.

Paul, W9AC


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[P.B. Christensen]

> "Lyle posted this a while back:
> http://www.mail-archive.com/elecraft@.../msg83487.html
describing the changes. Bob NW8L"

That refers to the Rev. C. changes current as of last October.  Main DSP
Board Rev. D now includes a hardware LPF circuit in the audio receive path.

Paul, W9AC

 

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