JT9 - WOW! Very sensitive indeed!

Discussion in 'Working Different Modes' started by W7UUU, Aug 18, 2014.

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  1. W7UUU

    W7UUU Principal Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Thanks for that Frank - never occurred to me to turn off AGC.

    And yes - I do the same thing with power - if I get a high signal report, the next go-round
    I drop the power accordingly. "The least amount of power needed to make the contact".
    Same thing when answering a CQ. On JT9 I usually start at 3 watts regardless of band
    or antenna involved. If I don't get him, next time I see him CQ I'll up to 5 watts and so
    on, until I'm the "guy that goes red". The highest I've ever used on JT9 is I believe 20 watts
    just one time, 15 one other time. All the rest were 10 and below. Not so much on JT65 - I've
    had to run up to 50 watts to "make it" a few times.

    Dave
    W7UUU
     
  2. N2ADV

    N2ADV XML Subscriber QRZ Page

    Dave, you are going to notice a huge difference with AGC off. You should kill AGC in any digital mode (there are always exceptions but I haven't found one yet). With AGC on, one person with a good antenna or the right kind of conditions will wipe out a lot of your view though zero fault of their own.

    I, too, halve my power if I get a "big" report but there have been times when I've been -01 on JT65 running milliwatts! Conditions play a huge part. Conversely, there have been times when I've gotten -24dB reports running 100 watts in poor conditions.

    For those experiencing issues with people "wiping out" your waterfall before crying "too much power! FOUL!" check your receive chain first before you start pointing fingers... Many (as in most) issues are on the receive end. Be prepared to ride the RF gain and adjust your settings when conditions change. If you never touch the settings on receive, you are doing it wrong! The JT modes are not "set and forget" modes... Fact is, you on the receive end have ZERO idea who is running what power. Period.
     
  3. K2NCC

    K2NCC Ham Member QRZ Page

    Highest I've ever used was about 90W. But I was on a dead band and zero hits on the PSKreporter. Worked up to that from 5W before I gave up and went to another band.

    92Wjt.png

    Had a guy from Japan use 400W (wow!) to work me, and he still only got a -17 report. Really depends on conditions, your antenna, location, etc.

    I'm sure his neighbors didn't appreciate it as much as I did. :eek:
     
  4. AA9G

    AA9G Ham Member QRZ Page

    What about when you get 15 decodes and 14 are the same person reported on 14 different frequencies? I always attributed that to a very distorted transmission.
     
  5. K2NCC

    K2NCC Ham Member QRZ Page

    Amen. I used to complain about how my old tube rig and it's accessories required me to spin/flip a dozen knobs/switches just to change bands. Now, even with everything just a mouse-click away, I find I'm still doing as many adjustments on a regular basis. Particularly when changing modes and software. In my experience, in spite of advancements in technology, the radio is not just punch-in-a-freq-and-PTT.
     
  6. K2NCC

    K2NCC Ham Member QRZ Page

    Honestly Dave, that's almost certainly something that can be fixed on your end. There are exceptions of course, people running compression and other errors or conditions. But I can't stress enough how turning off AGC and lowering your gain will fix so many wipe-outs and clutter. I had people tell me that long before I became a convert. Now I rarely have the AGC on.
     
  7. AA9G

    AA9G Ham Member QRZ Page

    Oh I have AGC off, and I've tried reducing gain. The only thing that really bugs me about when it occurs is sorting through the false decodes for real ones and having 5 seconds to do so! This mode can help keep your brain sharp, lol.
     
  8. K2NCC

    K2NCC Ham Member QRZ Page

    First thing I thought when I saw this is "Time to upgrade that computer OM!". Even with a computer that's several years old, I get near instant decode after the 47-second mark, regardless of how busy the waterfall is. Even with an older machine, you can unload some resources and tweak it to get better than 5 seconds work time.

    Unless that was just an exaggeration, but I've heard some folks don't get a decode until nearly the next minute.

    One thing about all those pretty colors and sounds, it's takes some horsepower.


    Oh, if someone hasn't taken the QSO from you in the meanwhile, you have about 20 seconds after the start of the next minute to begin your TX before the software makes you wait the next round.


    I always called terrestrial JT65/9 the lazy man's mode. Granted, it's not fully automatic, but it takes less work than any other mode I've used.
     
  9. K2NCC

    K2NCC Ham Member QRZ Page

    Oh, and if you really want the guy, and can't figure out where he is soon enough, it's perfectly fine to find an unoccupied spot and reply. Likely he'll move over to where you are.

    I do that often when there's a "pile-up" and might be the only one he decodes out of all the overlapping callers.
     
  10. AA9G

    AA9G Ham Member QRZ Page

    Cool, I will try that. There's nothing wrong with my computer, I reckon I exaggerated a bit. But it can still be hectic those few seconds if you get a number of CQ's and you're trying to see which one might be 'RARE'
     
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