[Elecraft] PSK31 on the K2

[Igor Sokolov]

> On 8/6/07, Igor Sokolov <ua9cdc at gmail.com> wrote:
> > I have made brake up box for microphone/sound card connection with
isolating
> > transformers. I find K2 to be pretty poor performer on PSK31. Has it
> > something to do with VFO stability of phase shift in the filters - I do
not
> > know. But weak signals coming from my IC765 get easyly decoded by the
> > program while if I use K2 the same program can decode only solid
signals. I
> > am not pleased with SSB performance of K2 either. Especially on TX.
Having
> > said that it is pretty good as CW contest rig and is almost on the par
with
> > my main radio.
> >
> > 73, Igor UA9CDC
> >
>
> The K2 has been my only radio for many years and I have made more
> PSK31 contacts than any other mode and I find the performance to be
> excellent. I have never had any trouble decoding weak signals - except
> for the day to day variations probably caused by the ionosphere,
> especially in northerly regions - and find it gives a very clean
> signal on transmit, IMD products -34dB when I measured using another
> receiver. The only annoyance is the fact that the frequency jumps by a
> few Hz when switching filters due to the limited resolution of the VFO
> DACs.
>
> I have also had complimentary reports on SSB (and it has always
> sounded good when I monitor it, as well.)
>
> I wonder if there is some problem with the SSB alignment on your K2.
> Perhaps the radio is close to a magnetic field such as a transformer
> which is modulating the VCO a little. When I made a power supply for
> my K2 I had to use a toroidal transformer for this reason.
>
> --
> Julian, G4ILO K2 s/n: 392  K3 s/n: ???
> G4ILO's Shack: www.g4ilo.com
> Ham-Directory: www.ham-directory.com

Thanks for your comments Julian. I do not think VCO modulation is the
reason. The radio is pretty far from the magnetic field sources. SSB (filter
and BFO) are aligned with the help of Spectrogram program.
I heard other K2 on the air and SSB signal was pretty similar to mine -
average and dim and  lacking high frequencies and punch. That will do for
day to day QSO but not for contests and pile ups. Anyway I will keep on
trying to do something about it before I give up:)

73, Igor UA9CDC