WSJT-X and 630 meters, a match made in heaven #FST4 #FST4W

Mark ~ AE2EA

When I decided to operate on the newly opened 630 meter band, the lack of commercial amateur radio equipment for the bands below 160 meters forced me to get creative So here's the approach that I took to get on 630 meters by utilizing a repurposed non directional beacon, a modified HP downconverter, and a reconfigured 80 meter dipole antenna.
I originally used JT9 and WSPR but have migrated to FST4 and FST4W. On 630 meters every db of S/N improvement helps and I really appreciate the inclusion of the MF and LF modes. It's astounding what the roughly 350 milliwatts EIRP that my antenna radiates can do. Claude Shannon would be proud of what the WSJT-X developers have done.

Watch it here:

Mark ~ AE2EA

Peter Hall, VK6HP


Thanks for posting the information about your MF station.  I was particularly interested in the re-used Southern Avionics Company NDB components since a small group which I formed a couple of years ago has obtained access to a de-commissioned NDB here in VK6.  The station used two SAC transmitters, various changeover and monitoring equipment, an auto-coupler, and a 22 m live mast with a somewhat indeterminate (as yet) radial field.   We are replacing a good deal of the original electronics with homebrew and commercial ham gear but we'll keep the autocoupler.  Operations will be initially on 630 m using a Zachtek exciter and a very robust push-pull Class D PA; about 25 W transmitter output should give us the legal 5 W EIRP.  In due course we'll have full remote operation supporting (at least) WSJT-X digital modes on 630 and 2200 m.  It's taken a while to get the site access details sorted out but I'm hopeful the worst is now - almost - behind us.  There's a placeholder QRZ page under the callsign VK6MJM which, in a nod to history, preserves the ident of the NDB.

More immediately, my home 630 m station in Perth uses a Kenwood transceiver as a low-level exciter and receiver; a homebrew 300 W Class D PA; a homebrew coupler; and an umbrella-loaded T transmit antenna which looks suspiciously like a re-purposed ZS6BKW HF doublet.  There's a bit more detail on my QRZ page if you're interested.  From this corner of the world all the activity is JT-mode digital and I was pleased that the WSJT-X team responded so promptly to a request to allow optional disabling of very slow envelope edges in the FST4 and 4W modes, thereby helping users of simple non-linear PAs to try the new modes with existing gear.  It's encouraging to see people experimenting with the new modes with, for example, reports of JA FST4W-1800 signals received in VK7 the other day.

73, Peter (Vk6HP).

Mark ~ AE2EA

The SAC PC-1000 autocoupler is the real prize in my 630 meter station. My transmitter is a SAC SS-250C with only 25 watts output and the EIRP is estimated somewhere between 20 dbm and 26 dbm, so a more powerful amplifier is in my future, along with some antenna improvements. Still, I've made 3500 km JT9 contacts when conditions are good.

I've played around with the -900 and -1800 modes, but my FTDX-3000 has too much frequency drift over those time periods. I've been thinking of programming my GPSDO locked arbitrary waveform generator as a FST4W exciter. If I do I might give 2200 meters a shot.

I enjoyed reading your QRZ page and have downloaded your amplifier info for inspiration. Thanks.

73, Mark ~ AE2EA