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TX Power Variation

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  • johnmellish
    Hi folks. When using JT65 my tx power varies slightly with the tones being sent. I guess this is caused by my tx bandpass response to the different tones but
    Message 1 of 9 , Dec 23, 2009
      Hi folks. When using JT65 my tx power varies slightly with the tones being sent. I guess this is caused by my tx bandpass response to the different tones but would like some reassurance that it is normal. Worse case variation is about 18W to 22 W so its less than 1dB.
      Many thanks - especially to JT for such a great mode for stations with no outside antennas like myself. Have a good Christmas - John (G4HUK)
    • Ben Nardi
      John, I have a Icom 706 and have noted similar power variations across the audio passband on all the digital modes. This is particularly noticeable on modes
      Message 2 of 9 , Dec 23, 2009
        John,
         
        I have a Icom 706 and have noted similar power variations across the audio passband on all the digital modes. This is particularly noticeable on modes that require linear operation such as PSK31. I would consider passband variations on the order of 1db as normal and within spec. for most SSB equipment.
         
        Regards
         
        Ben W3ZUP


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      • WY5R
        You sparked my curiosity, and I ran a test. On a Kenwood TS-2000 set for 50 watts into a dummy load, the variance approximately 1 Watt (49 to 50 Watts). I
        Message 3 of 9 , Dec 23, 2009
          You sparked my curiosity, and I ran a test.  On a Kenwood TS-2000 set for 50 watts into a dummy load, the variance approximately 1 Watt (49 to 50 Watts).  I looked to make sure that I had no audio TX DSP filter running.  I can't say if your experience is normal, as this is the only rig that I've made such a test.
           
          Merry Christmas and Happy New Year,
          KD - WY5R
           
           
          ----- Original Message -----
          Sent: Wednesday, December 23, 2009 5:03 AM
          Subject: [wsjtgroup] TX Power Variation

           

          Hi folks. When using JT65 my tx power varies slightly with the tones being sent. I guess this is caused by my tx bandpass response to the different tones but would like some reassurance that it is normal. Worse case variation is about 18W to 22 W so its less than 1dB.
          Many thanks - especially to JT for such a great mode for stations with no outside antennas like myself. Have a good Christmas - John (G4HUK)

        • Charles Miller
          I encountered this effect on my IC756PRO3 and IC746PRO. Both have menu provisions to adjust the transmit audio response if desired. I also notice it in the
          Message 4 of 9 , Dec 23, 2009
            I encountered this effect on my IC756PRO3 and IC746PRO. Both
            have menu provisions to adjust the transmit audio response if
            desired. I also notice it in the Spectran display of receive
            passband. This may be adjusted as well on some rigs. I don't
            know whether these adjustments are available on your rig. At any
            rate, it's a minor issue.

            73, Chuck N6KW

            On 2009-12-23 11:03, johnmellish wrote:
            > Hi folks. When using JT65 my tx power varies slightly with the tones being sent. I guess this is caused by my tx bandpass response to the different tones but would like some reassurance that it is normal. Worse case variation is about 18W to 22 W so its less than 1dB.
            > Many thanks - especially to JT for such a great mode for stations with no outside antennas like myself. Have a good Christmas - John (G4HUK)
            >
            >
            >
            > ------------------------------------
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          • Jordan
            Different tones are bound to create different levels of RF, unless you have a perfectly flat response across the passband...There is also a slight pulsing
            Message 5 of 9 , Dec 23, 2009
              Different tones are bound to create different levels of RF, unless you have a perfectly flat response across the passband...There is also a slight 'pulsing' effect as the rise/fall times of tones, ALC if any, etc....
               
              The pulses, or tones, can be seen on my grid current meters in my amps as well...It let's me know I have some headroom left in the signal and helps keep the signal clean....
               
              Happy Holidays....73...Jordan VE6ZT
               
               
              ----- Original Message -----
              Sent: Wednesday, December 23, 2009 2:15 PM
              Subject: Re: [wsjtgroup] TX Power Variation

               

              I encountered this effect on my IC756PRO3 and IC746PRO. Both
              have menu provisions to adjust the transmit audio response if
              desired. I also notice it in the Spectran display of receive
              passband. This may be adjusted as well on some rigs. I don't
              know whether these adjustments are available on your rig. At any
              rate, it's a minor issue.

              73, Chuck N6KW

              On 2009-12-23 11:03, johnmellish wrote:
              > Hi folks. When using JT65 my tx power varies slightly with the tones being sent. I guess this is caused by my tx bandpass response to the different tones but would like some reassurance that it is normal. Worse case variation is about 18W to 22 W so its less than 1dB.
              > Many thanks - especially to JT for such a great mode for stations with no outside antennas like myself. Have a good Christmas - John (G4HUK)
              >
              >
              >
              > ------------ --------- --------- ------
              >
              > To unsubscribe, send an email to:
              > wsjtgroup-unsubscri be@yahoogroups. com
              >
              > WSJTGroup HomePage http://www.ykc. com/wa5ufh/
              >
              >
              >
              >
              >
              > Yahoo! Groups Links
              >
              >
              >
              >

            • Jordan
              Ooops...I should have said screen current....not grid current...agn...73...VE6ZT ... From: Jordan To: Charles Miller ; johnmellish Cc:
              Message 6 of 9 , Dec 23, 2009
                Ooops...I should have said screen current....not grid current...agn...73...VE6ZT
                 
                 
                ----- Original Message -----
                From: Jordan
                Sent: Wednesday, December 23, 2009 2:45 PM
                Subject: Re: [wsjtgroup] TX Power Variation

                Different tones are bound to create different levels of RF, unless you have a perfectly flat response across the passband...There is also a slight 'pulsing' effect as the rise/fall times of tones, ALC if any, etc....
                 
                The pulses, or tones, can be seen on my grid current meters in my amps as well...It let's me know I have some headroom left in the signal and helps keep the signal clean....
                 
                Happy Holidays....73...Jordan VE6ZT
                 
                 
                ----- Original Message -----
                Sent: Wednesday, December 23, 2009 2:15 PM
                Subject: Re: [wsjtgroup] TX Power Variation

                 

                I encountered this effect on my IC756PRO3 and IC746PRO. Both
                have menu provisions to adjust the transmit audio response if
                desired. I also notice it in the Spectran display of receive
                passband. This may be adjusted as well on some rigs. I don't
                know whether these adjustments are available on your rig. At any
                rate, it's a minor issue.

                73, Chuck N6KW

                On 2009-12-23 11:03, johnmellish wrote:
                > Hi folks. When using JT65 my tx power varies slightly with the tones being sent. I guess this is caused by my tx bandpass response to the different tones but would like some reassurance that it is normal. Worse case variation is about 18W to 22 W so its less than 1dB.
                > Many thanks - especially to JT for such a great mode for stations with no outside antennas like myself. Have a good Christmas - John (G4HUK)
                >
                >
                >
                > ------------ --------- --------- ------
                >
                > To unsubscribe, send an email to:
                > wsjtgroup-unsubscri be@yahoogroups. com
                >
                > WSJTGroup HomePage http://www.ykc. com/wa5ufh/
                >
                >
                >
                >
                >
                > Yahoo! Groups Links
                >
                >
                >
                >

              • Steve Chambers
                Hi John Its worth checking that the sound card is not using any form of audio boosting. I found that I had a similar power variation using a sound blaster, on
                Message 7 of 9 , Dec 23, 2009
                  Hi John
                  Its worth checking that the sound card is not using any form of audio boosting. I found that I had a similar power variation using a sound blaster, on turning off all the boost and compression within the sound card settings, the power verification was gone.
                  I hope that helps

                  Merry Christmas and a happy new year to all in the group.
                  Steve G8IHT 

                • John Mellish
                  Many thanks everyone, your comments were very helpful. Wishing you all a great Christmas and a happy and healthy New Year. 73 John (G4HUK)
                  Message 8 of 9 , Dec 24, 2009
                    Many thanks everyone, your comments were very helpful.
                     
                    Wishing you all a great Christmas and a happy and healthy New Year.
                     
                    73 John (G4HUK)


                  • hb9ari
                    Hi Steve, Same problem here; using an Audigy 2 ZS Notebook (PCMCIA). Problem solved today by loading new SB drivers. Power variation was over 3dB with some DF.
                    Message 9 of 9 , Dec 25, 2009
                      Hi Steve,

                      Same problem here; using an Audigy 2 ZS Notebook (PCMCIA).
                      Problem solved today by loading new SB drivers.
                      Power variation was over 3dB with some DF.
                      Now i'm well under 1dB over DF +/- 800Hz. around 1200Hz.
                      It's now compatible with TX filter ripple.
                      With audio only, variation is under 0.2 dB.

                      Too late for a Merry Christmas... but an Happy New Year!

                      I enjoy to "see" you next Spring when ready from my
                      camping site!

                      73 QRO,
                      Rudi, HB9ARI


                      Steve Chambers wrote:
                      > Hi John
                      > Its worth checking that the sound card is not using any form of audio
                      > boosting. I found that I had a similar power variation using a sound
                      > blaster, on turning off all the boost and compression within the sound
                      > card settings, the power verification was gone.
                      > I hope that helps
                      >
                      > Merry Christmas and a happy new year to all in the group.
                      > Steve G8IHT
                      >
                      >
                      >
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