Just to elaborate on what Evert is saying below -- You want to tune the
receiver frequency using RIT, with the FSK441 DF (Delta frequency) reading as
your guide. You do NOT want to tweak with the transmit frequency. Set your
main VFO to the frequency agreed upon (e.g., 50.255 MHz) and leave it there.
The other guy will get a DF reading indicating how far your frequency is from
his frequency, and he will adjust his RIT to compensate for that (if
necessary). You can do the same for his signal. If you change your TX
frequency using either the VFO or XIT, that will mess him all up. :-) And
vice-versa. Use only the RIT for receive tuning.
In truth, the WSJT FSK441 decode engine is capable of automatically resolving
a DF of up to 400 Hz. You may be able to filter out a lot of noise by tuning
the signal closer with RIT such that the reported DF number gets smaller, and
then narrowing the WSJT passband accordingly -- but this is usually
unnecessary with pings of moderate or better strength.
Bill W5WVO
Evert Bakker (PA2KW) wrote:
Hi Mike and Lenny,
Using FSK441, don't change the tones (as far as I know you can't).
Just tune in for the RX signal and the DF will show you how to tune
in on your partner. From then on it should be OK.
73's, Evert PA2KW
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of AD6XY - Mike
Sent: Monday, March 03, 2008 22:41
To: [email protected]
Subject: Re: [Elecraft] Anyone using WSJT with a K2?
I tried on our 70 MHz band with my XV-70. The same goes for JT65 as
used by our beacons where I found the tuning very critical.
I thought nothing of this but maybe you have a point.
Some weeks later on, I tried decoding JT65 on 23cm via an Icom IC910
and it worked fine. It may be the K2 filter but more likely it was
just conditions.
Although the tones are as specified, the tones in practice will
depend on your calibration and Doppler shifts. The WSJT program
should be able to decode the signals if they are off frequency. If
you know your filter is off above 2 kHz, it might pay to tune a few
100Hz higher up the band. That way signals with positive Doppler are
more likely to fall in the pass band.
I am not sure the filter phase response is all that important here
because the mode is not phase coherent.
Filter ripple may be a problem on transmit, especially is if is as
severe as 3-4 dB. It looks like you are receiving and this might be
the cause of less QSOs. Try and alter the TX audio tone frequency but
this time down a bit so it falls into the SSB pass band. You should
not need to alter the filter - simply change WSJT tones instead.
Mike
w2bvh wrote:
Has anyone on the list used WSJT FSK441 mode with a K2? If so I'd
like to hear about your experience.
I've tried it with a XV-50 that I recently built and so far have just
limited success. I have decoded about 2-3 transmissions (plus another
2-4 partials) over 3 Saturday morning "random hour" WSJT meteor
scatter sessions on 6 meters, but so far no successful qsos. I
operated with the K2 set for agc off, usb, and filter OPT1.
My K2 is sn 1520 and was updated to the the most recent firmware at
the same time as the XV50 build in order to accommodate the XV50 and
the KIO2 which also had to be added to the K2 for 6 meter operation.
According to the wsjt manual FSK441 uses 882, 1323 1764 and 2205 Hz
tones in its encoding. My K2's OPT1 filter has the 2205 Hz tone on
the IF filters shoulder. By eye its about 3-4 db below the passband.
(In a previous version of this email I attached a jpg of the
spectrogram plot, but evidently emails with attachments are not
permitted here. I can send you a copy directly if it would help).
Is it possible there is too much attenuation or phase distortion of
the 2205 Hz signaling element for easy WSJT operation? I have the
OPT1 filter adjusted for the best sounding ssb voice signal
(according to my xyl's careful listening). If it's necessary to move
the filter up 150-200 Hz for WSJT, it will affect how my voice
comes across in ssb.
What are my best options for good both ssb and wsjt operation with
the K2? Are compromises required here or is there a way to get both
good SSB and good WSJT?
Thanks in advance.
73,
Lenny W2BVH
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