K3 PSK Dreaming

[Bill Frantz]

Background:

I am a relatively inexperienced operator with a spiffy new basic
K3. (The only installed accessory is the K144XV and its required
KXV3A.) To give an idea of where I'm at as an operator, my first
use of the K3 was to copy W1AW slow code practice.

Most of my HF QSOs are PSK31 on 20 meters using a Small Wonder
Labs PSK-20, which is basically a single frequency, direct
conversion, SSB transceiver covering about 3.5 KHz of the PSK
subband on 20 meters. Because my MacBook Pro has only one audio
connector run in half duplex, I use a SignaLink USB interface.
With this setup I have been able to work over 45 states.

I've fallen in love with waterfalls. I'm a good prospect for a
P3, once the budget and KI6SLX, my wife recover from the K3. :-)

I very quickly set the K3 up for sound-card mode operation by
moving the audio cables from the PSK-20 to the K3 and turning on
the K3's VOX. After setting the Config settings following the
good description in the manual, I was able to make my first QSO
on the K3.


The dream:

I read in the "Theory of Operation" section of the manual that
audio is generated in a 24 bit DtoA converter and passed to line
out. Wait a minute. The K3 is producing analog audio so I can
immediately convert it back to digital. Ouch. (And the SignaLink
is only 16 bits.)

What I would like to see is an accessory for the K3 that looks
like a 24 bit sound card to the computer. Since the data rates
are too fast for RS-232, and software already supports USB, a
USB interface seems the way to go. Including the KUSB function
in the interface could be nice way to reduce cable clutter.

This accessory would eliminate one audio level control, and
allow more of the K3's dynamic range to show through to the
computer. I would probably reduce the times I need to use the
notch filter to filter down a strong local station.

Cheers - Bill, AE6JV

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[WB4SON]

You are pretty much describing the ONE thing I miss that was on my Icom
IC-9100 that is not on my K3 -- A single USB connection that has rig
control plus audio in and out (Not that Icom was perfect -- they left out a
critical adjustment for receive audio level, and some way to send CW via
rig command or port control, and a means switching into XMIT via port
control).

I'd love to see that sort of change made to a future version of the KIO3
card.

As a reference, if you change from 16-bit resolution to 24-bit resolution,
the JT65-HF minimum signal decode will go from about -24 dB to -32 dB --
that's a huge improvement in weak signal decode.

73, Bob, WB4SON



On Mon, Mar 26, 2012 at 5:20 PM, Bill Frantz <[hidden email]> wrote:

> ...What I would like to see is an accessory for the K3 that looks
>
like a 24 bit sound card to the computer. Since the data rates

> are too fast for RS-232, and software already supports USB, a
> USB interface seems the way to go. Including the KUSB function
> in the interface could be nice way to reduce cable clutter.
>
> This accessory would eliminate one audio level control, and
> allow more of the K3's dynamic range to show through to the
> computer. I would probably reduce the times I need to use the
> notch filter to filter down a strong local station.
>
> Cheers - Bill, AE6JV
>

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