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AFSK TX power level

Craig K9CT
Craig K9CT Member ✭✭
edited February 2019 in SmartSDR for Windows
I am using MMTTY for AFSK and receiving very well. However, I have observed low power despite DAX at almost any audio level. It seems to me I had great output before but can't seem to figure out what has happened. I assume the TX bandpass is the same as the RX bandpass and allows the tones to be in the pass band. I am using 2125 and centering on 2200 for RX. 

My power on CW and SSB is right on. So nothing wrong with the 6700. 

Any hints? 

Thanks, Craig K9CT

Answers

  • George KF2T
    George KF2T Member ✭✭✭
    edited February 2019
    Have you tried the TX slider in the DAX Control Panel? And/or another DAX channel?
  • Craig K9CT
    Craig K9CT Member ✭✭
    edited April 2016
    Yes, I have but I did it again to confirm. If I push the slider on DAX TX to 51 I get 100 watts out. However, the audio level on the TX panel shows level in the RED. I would think GREEN level would be linear but YELLOW and RED would be distortion. Are your levels about this to transmit 100W?


  • Al K0VM
    Al K0VM Retired Member ✭✭✭
    edited November 2017
    Craig,
      With single tone DIGI modes, with the  level meter just at the red threshold, you should have full output ( ~100 watts PEP ).  The PA in the radio should still be in a linear region but internal ALC is about to be applied..  I believe that Yellow does not indicate distortion but indicates that processing is begining to be applied applied in SSB modes.
      The TX band pass is independent of the RX band width.. See TX Low/High cut ( applies to all modes )  in the PHONE panel

    AL, K0VM
  • George KF2T
    George KF2T Member ✭✭✭
    edited February 2019
    Craig, here are the values here:
    Software is WSJT ver 10
    DAX 3 TX level: 40
    Audio "Level" one notch below red

    RF Power on F6500 meter: 80 watts
    Confirmed by external meter

    Same in SSB with tone generator on microphone input.

    I guess I'm "missing" 20 watts somewhere. Never really noticed/cared until now :-) Will try the usual reset sequence and see. 

    I'm usually on JT modes, so don't really have a lot of call for such "high power."

    Thanks for the report.

    73, Geo

  • km9r.mike
    km9r.mike Member ✭✭
    edited May 2015
    Hi Craig. Ensure that RF slider on the TX panel is set to the desired power out level. I usually have it at 100w then I increase or decrease dax tx level to achieve desired transmit output for mmtty ops with the " level " meter on ssdr peaking below zero at all times. I will also run it peaking in the yellow and have had no complaints wrt tx distortion. Since your level meter is responding to your adjustments in dax tx level (it will even do this with RF slider set to zero watts) I am thinking perhaps your rf slider was set to a lower value in dig lower mode and you might have not noticed it. It sounds as if you increased dax tx level to increase your TX power but ended up bumping against the yellow and red "level meter" indications because you were not seeing your usual TX output, however, if your RF slider was inadvertently set to say 50w well then 50w or less is what you will get when you peak out the level meter below zero. Hope this works.

    cul,
    mike
  • Joe Duerbusch
    Joe Duerbusch Member
    edited April 2015
    Hi. I think you would have better luck with MMTTY if you used low tones instead of the REAL RTTY tones of 2125/2295.  I set MMTTY for 1445 Mark and then I have to use NET to transmit on the same freq.  Now you can use the RTTY filters in the Flex down to 250 HZ.  Writelog and N1NN both have an offset function which will set the correct frequency from/to the Clusters.  Only big problem is that you cannot Click on a RTTY signal as the Flex will go to the Carrier Frequency and not the Mark.
    I am using a Flex 6300 with Writelog and MMTTY plugin.
    Hope this helps, cu at Dayton.

    Joe K0BX

  • Craig K9CT
    Craig K9CT Member ✭✭
    edited April 2016
    Thanks to everyone for your thoughts. I was concerned that the audio level was near the RED line to be at 100 watts. I thought that in prior time, it was in the GREEN setting levels on DAX. 

    Joe...your comments are quite useful. For DX and contest spots, the Mark frequency needs to be the click freq. The center of the filter needs to follow the Mark freq. as well. 

    See you at Dayton

    73, Craig K9CT
  • Joe Duerbusch
    Joe Duerbusch Member
    edited April 2015
    Hi Craig, I guess I wasn't too clear about the "Click Freq".  If you add the offset in Writelog or N1MM then clicking on the Telnet spots will go to the correct Frequency.  It ONLY clicking on the Station on the FLEX screen that doesn't work correctly.  It doesn't work, Flex design, Try Clicking on ANY RTTY station on the Flex display.  The Yellow line will always go to the Carrier Frequency and not the Mark frequency.  I sure wish they would fix it.  It does work correctly on CW so I know it can be done.  

    FLEX has decided that 1500HZ is the center frequeny for all digital modes.  If you want to use the narrow filters, you must use low tones and put the mode in DIGI.  

    Hope this helps.

    73
    Joe K0BX

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