JT Modes on 80m

Discussion in 'Working Different Modes' started by G0VKT, Oct 12, 2017.

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  1. G0VKT

    G0VKT Ham Member QRZ Page

    I like the JT modes on HF as I have a very modest station. 100w to a 45' inverted L with the chassis of my mobile home as the ground.

    Last weekend I decided to try 80m for the first time as the band didn't have much of the background noise that has been present of late.

    I got up at about 3am on Sunday and there were loads of digital signals. Almost all were using FT8. Using 50w and FT8 I worked a station in Michigan and then one in Columbia. Very pleased indeed! And surprised at the low signal levels that could be worked.

    Just being curious, but I assumed that JT9/65 would be better. Is there something about FT8 that suits this band better. Paths that are only present for a short time? Or nothing more than FT8 being the popular new mode at the moment? The higher bands seem to have more of a mix.

    Thanks

    Paul
     
  2. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    No, there is nothing that make FT8 better on 80m nor better than JT9/65. I find FT8 noticeably poorer at making contacts (lower senstivity). I can often see dozens of signals on the waterfall that cannot be decoded by FT8.
     
  3. KJ3N

    KJ3N Ham Member QRZ Page

    That's by design. What you gain it speed of the mode, you give up in ability to decode at weaker levels.

    Then I would suggest your setup needs tweaking. I can usually decode signals that are marginally discernible on my waterfall. The lower limit (as I understand it) for FT8 is roughly -23. I can occasionally get decodes as low as -24, but they're rare. Typically, -22 seems to be my limit and those are pretty faint on my display.
     
  4. KJ4VTH

    KJ4VTH Ham Member QRZ Page

    Been working JT-65 for a few years and it works extremely well in various band conditions. Recently tried FT-8 and note the number of repeats often required to confirm a contact make it no faster than JT-65. Not always but often.
     
  5. ND6M

    ND6M Ham Member QRZ Page

    FT8, a really great piece of software, but, it has rapidly become a major source of QRM in the digital band segments.

    It's not the FT-8 protocol itself that is the problem, the problem is the LIDS that that enable the call CQ function and then call, and call, and call, and ,...................well, you get the idea..

    I recently noted a station that called CQ constantly for over an hour and never received a reply, perhaps the "operator" just went out for lunch.
     
  6. KJ4VTH

    KJ4VTH Ham Member QRZ Page

    WSJT-X has TX timeout feature but not enabled by default:(
     
  7. NS8N

    NS8N Premium Subscriber QRZ Page

    I've noticed that the auto sequence feature doesn't work so well if you're the one calling CQ. I've tried with it enabled and yes it will keep putting my CQ out and I'm not getting any responses. But if I instead put out one or two CQs then hit the stop transmit button, I'll get a response back.

    I suspect it is a time sync issue between our stations but that is just my theory, I don't have any evidence to back up that claim. The auto sequence works great if you are responding to a CQ, however.
     
  8. KJ4VTH

    KJ4VTH Ham Member QRZ Page

    Interesting observation Brandon. I have answered some CQs and the other party calls CQ again & again. Yet on PSK Reporter I'm being heard by that station or another nearby. Maybe that "feature" is why.
     
  9. VA3VF

    VA3VF Ham Member QRZ Page

    Is your PC clock accurate to +/- 1.5 seconds (althought recent revisions are good to up to =/-2.5 seconds)?

    Do you have Call 1st enabled?
     
  10. VA3VF

    VA3VF Ham Member QRZ Page

    FT8 is about 3 dBs worse than JT65. It can make a difference in making a contact or not. On the other hand, the 15 seconds cycle compensates this difference on higher bands, where propagation conditions can change very fast. On 160, JT65 has an edge. On 6M, FT8 does.
     

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