WSJT-X for LF: Now I really will have to look at a top band antenna…

A couple of days ago, I read a post that the wonderful Joe Taylor, K1JT  was working on a new mode for use on LF. It wasn’t until this evening that I read up a little more.

Joe says, on

If you are on 160 meters, or perhaps on 472 or 137 kHz, you may be interested in a new mode called JT9, designed especially for making QSOs on these bands. JT9 uses the structured messages introduced in 2003 for the JT65 mode, now widely used for EME and for QRP operations at HF. JT9 can operate at signal levels as low as -27 dB (in a 2500 Hz reference bandwidth), with one-minute timed transmissions. It also offers slower transmissions of 2, 5, 10 and 30 minutes duration, and the slowest mode can decode signals as weak as -40 dB. With one-minute transmissions, submode JT9-1 has a total bandwidth of 15.6 Hz — less than one-tenth the bandwidth of a JT65A signal. The other submodes are narrower still: a JT9-30 signal occupies about 0.4 Hz total bandwidth.

JT9 is implemented in an experimental version of WSJT called WSJT-X. Some further details can be found at ,
and an early version of WSJT-X can be downloaded from .
If you want to try JT9, I suggest using dial frequency 1838, which is also used for JT65A, PSK31, and MFSK. In default configuration WSJT-X allows transmission and reception 1 to 2 kHz above the dial frequency.
Please note: WSJT-X is in an early development stage. Your feedback (direct email to me is best) will be much appreciated. And feel free to email me for a sked!
— 73, Joe, K1JT”
This looks interesting and surely has to be the way for those of us who have never been able to work *anything* on 160m to finally do something interesting on the band. I’ve just downloaded the latest WSJT-X release, which differs from the link in the post above, but it’s linked from the main WSJT home page
The program seems to be running ok and I’m monitoring 1838khz, so I will leave it going this evening and see how things work out.
Thank you Joe!
Tim Kirby, G4VXE, is a regular contributor to and writes from Oxfordshire, England. Contact him at [email protected].

9 Responses to “WSJT-X for LF: Now I really will have to look at a top band antenna…”

  • Michael - N5TGL:

    This is very cool.

    I ran JT65 on 160m last winter and had a blast, even though I got the antenna (Inv-L) up late. Here it is over a year later and I still (haha) am late getting the antenna up. Maybe I’ll get one last mow in for the season and then string it back up again. If I’m very industrious, I’ll set up the K9AY loop system I bought. In fact, I may have to do that just to make sure everything works. I got it with the intention of having it when we transferred to the UK, which seems to be in a bit of a holding pattern now.

    I also had reasonably good luck with SSB, but this year I’ll have some real power with the Clipperton L that I bought.

    Hope to see you on the bands!

  • David - N1ZHE:

    A friend who lives about 15 miles away and I were experimenting on 1.838 with JT9 the other night. We got down to one watt output, still perfect copy.

    I’ll have to try someone a little farther away to experiment with.

    If you want to try this mode out but can’t work on 160 meters, look at 10.130. Lots of activity there except for the wee hours EST time.

    David, N1ZHE

  • Steve G4AZB:

    On 1939.5 Mhz Also

  • Steve G4AZB:

    Sorry 1.839.5 Mhz

  • k2ncc Frank:

    I’ve had a handful of QSOs w/JT9-1 and look forward to more.

    So far I’ve seen action on 10.130, 14.078, 18.103 and 24.919.

    vy 73, de frank k2ncc in Oregon

  • ce1fmr:

    muy bueno toda la publicacion

  • n8tl:

    Interesting website look forward to reading newsletter.

  • matt wd9dmm:

    HI just became aware of JT9.I only have bands 10-20-40.How much equip.doI need
    and how expensive is it I have a complete station at moment and use mostly cw.I have one windows vista computer.
    look forward to hearing from you Matt Furlong wd9dmm

  • Bob KH6KG:

    I have been a Top Band user for over 30 years. I will be using JT-65 from my sunset here in Waikiki and hope to make my first QSO on that QRG and mode.

    I will call CQ until someone hears me.

    73 Bob KH6KG

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