[Elecraft] 6 KHz filter and PSK31

[Cortland Richmond]

Soundcarc modes have one large problem used this way; harmonics of low
tones may produce a multiple (and unauthorized) signal in the passband. 
That's a good reason to use tones near the high frequency cutoff.   And
that's not counting transmit IMD.


Cortland
KA5S


> [Original Message]
> Date: Sat, 20 Sep 2008 00:40:38 -0600
> From: "Bob Cunnings" <bob.cunnings at gmail.com>
> Subject: Re: [Elecraft] K3 PSK31 with Digipan
> To: elecraft at mailman.qth.net
> Message-ID:
> 	<d5c86c8d0809192340q57845809p3b9e82983578814f at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> It finally dawned on me that the 6kHz filter could be put to work for
> soundcard modes in both transmit and receive by enabling ESSB and
> using USB or LSB instead of DATA A. Indeed, it works just fine with BW
> set to 4kHz and shift adjusted to put center at 1800 or so. With DM
> 780 set to max width (3.9 kHz) the waterfall just about fills the
> screen and there's almost 3.5 kHz bandwidth for transmit and receive.
> This gives a wider field for casual point and click PSK31 operation -
> nice for a simple setup like mine where there is no computer control
> of the radio, and I want to keep the knob twirling on the rig to a
> minimum (the interface consists only of 2 audio cables between laptop
> and rig with VOX keying. TX EQ flat, AGC and compressor disabled of
> course).
>
> Bob NW8L