[Elecraft] Anyone using WSJT with a K2?

[Bill W5WVO]

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: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of AD6XY - Mike
> Sent: Monday, March 03, 2008 22:41
> To: elecraft at mailman.qth.net
> 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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