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Can't null TX image

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  • ugless
    I am having trouble nulling the image on transmit, and I was hoping to get some advice. I am using quisk 3.6.16 to do the iq handling. I was able to null the
    Message 1 of 18 , May 18, 2014
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      I am having trouble nulling the image on transmit, and I was hoping to get some advice.


      I am using quisk 3.6.16 to do the iq handling. I was able to null the rx image by tuning near 15 MHz and sliding Quisk's "Rx Phase" slider to about 3 degrees.


      To null the tx image, I powered on another transceiver (Yaesu FT-840) nearby with no antenna. Then, using Quisk's CW mode, I keyed down and verified the tone was heard at the proper frequency (shows about S9+20). Then, I tuned the transceiver to the image frequency and keyed down again, and I also see S9+20! No matter how much I adjust the "Tx Phase" slider, the S-meter doesn't move. I also tried physically swapping the right/left channels with no effect.


      Any ideas?

    • MIKE DURKIN
      Check you have both I and Q for Tx hooked up ... Disconnect one and Tx ... if you get power, then reconnect and disconnect the other, Tx again if you get power
      Message 2 of 18 , May 18, 2014
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        Check you have both I and Q for Tx hooked up ...

        Disconnect one and Tx ... if you get power, then reconnect and disconnect the other, Tx again if you get power then both cables are connected ok ...

        Thats the first place i would start ...

        Mike KC7NOA


        To: softrock40@yahoogroups.com
        From: softrock40@yahoogroups.com
        Date: Sun, 18 May 2014 10:51:35 -0700
        Subject: [softrock40] Can't null TX image

         

        I am having trouble nulling the image on transmit, and I was hoping to get some advice.


        I am using quisk 3.6.16 to do the iq handling. I was able to null the rx image by tuning near 15 MHz and sliding Quisk's "Rx Phase" slider to about 3 degrees.


        To null the tx image, I powered on another transceiver (Yaesu FT-840) nearby with no antenna. Then, using Quisk's CW mode, I keyed down and verified the tone was heard at the proper frequency (shows about S9+20). Then, I tuned the transceiver to the image frequency and keyed down again, and I also see S9+20! No matter how much I adjust the "Tx Phase" slider, the S-meter doesn't move. I also tried physically swapping the right/left channels with no effect.


        Any ideas?

      • ugless
        Ok, cool. Just did that and got power with both channels.
        Message 3 of 18 , May 18, 2014
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          Ok, cool. Just did that and got power with both channels.
        • warrenallgyer
          This may be way too simple but it sounds like your sound card is either in mono mode or does not accept stereo inputs. If you have had it working in stereo
          Message 4 of 18 , May 18, 2014
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            This may be way too simple but it sounds like your sound card is either in mono mode or does not accept stereo inputs. If you have had it working in stereo before then check the setup for the record device. It must be capable of stereo and set for a 2 channel mode.

            Warren Allgyer
            9V1TD
          • Sid Boyce
            It would be Line Out for TX. Wonder what the sound card is? Usually on some sound cards it s the Mic that is mono. 73 ... Sid. ... -- Sid Boyce ... Hamradio
            Message 5 of 18 , May 18, 2014
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              It would be Line Out for TX.
              Wonder what the sound card is?
              Usually on some sound cards it's the Mic that is mono.
              73 ... Sid.

              On 18/05/14 21:48, allgyer@... [softrock40] wrote:
               

              This may be way too simple but it sounds like your sound card is either in mono mode or does not accept stereo inputs. If you have had it working in stereo before then check the setup for the record device. It must be capable of stereo and set for a 2 channel mode.

              Warren Allgyer
              9V1TD



              -- 
              Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
              Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
              Senior Staff Specialist, Cricket Coach
              Microsoft Windows Free Zone - Linux used for all Computing Tasks
              
            • warrenallgyer
              Making sure there is no confusion: It would be the Line In connector on the RXTX (sounds like he has that right) and it should be connected to the Line In
              Message 6 of 18 , May 18, 2014
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                Making sure there is no confusion: It would be the Line In connector on the RXTX (sounds like he has that right) and it should be connected to the Line In connector of the sound card. If it is connected to the Mic In then, I agree, it is likely Mono. But even the Line In connection can be usually set for 1 CH (mono) in the Record Device/Properties/Advanced control panel. It should be confirmed it is set for 2 CH mode.

                Warren Allgyer
                9V1TD
              • ugless
                I m talking about transmitting, so we are talking about the Line Out of the sound card and the RXTX. The sound card is an M-Audio Delta AP 192, and its line
                Message 7 of 18 , May 18, 2014
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                  I'm talking about transmitting, so we are talking about the Line Out of the sound card and the RXTX.

                  The sound card is an M-Audio Delta AP 192, and its line out is specifically broken out into 1/4 inch left and right channels.
                • MIKE DURKIN
                  Yea .. if the cables are not the problem ... you have a problem with your build .... Mike KC7NOA To: softrock40@yahoogroups.com From:
                  Message 8 of 18 , May 18, 2014
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                    Yea .. if the cables are not the problem ... you have a problem with your build ....

                    Mike KC7NOA


                    To: softrock40@yahoogroups.com
                    From: softrock40@yahoogroups.com
                    Date: Sun, 18 May 2014 17:37:49 -0700
                    Subject: [softrock40] Re: Can't null TX image

                     
                    I'm talking about transmitting, so we are talking about the Line Out of the sound card and the RXTX.

                    The sound card is an M-Audio Delta AP 192, and its line out is specifically broken out into 1/4 inch left and right channels.

                  • ugless
                    Argh...I spent all day doing basic checks with a multimeter. No shorts/bridges that I can find in the TX chain. Are there some more advanced tests I can do?
                    Message 9 of 18 , May 18, 2014
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                      Argh...I spent all day doing basic checks with a multimeter. No shorts/bridges that I can find in the TX chain. Are there some more advanced tests I can do?
                    • warrenallgyer
                      Yup... my bad! Line Out on both. In fact.... please ignore my post. I was completely confused. Sorry! Warren Allgyer 9V1TD
                      Message 10 of 18 , May 18, 2014
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                        Yup... my bad! Line Out on both.

                        In fact.... please ignore my post. I was completely confused. Sorry!

                        Warren Allgyer
                        9V1TD
                      • MIKE DURKIN
                        Would need a scope i guess ... and an audio gen (id just use a pc program)-- also might want to disable some of the Tx chain -- to keep from over heating the
                        Message 11 of 18 , May 18, 2014
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                          Would need a scope i guess ... and an audio gen (id just use a pc program)-- also might want to disable some of the Tx chain -- to keep from over heating the driver/final ....

                          Also im not 100% sure on which RF front end your using but also might remove the I/Q combining/splitting transformer (bty  ... that might be the area of problem -- its where all quadrature type transceivers combine/split the phase shifted Rf signal) .. then you can verify that the Rf I and Q make it to the Rf transformer (with out reflected signal making it back the other side of the transformer -- get it?)

                          Mike kc7noa


                          To: softrock40@yahoogroups.com
                          From: softrock40@yahoogroups.com
                          Date: Sun, 18 May 2014 18:57:18 -0700
                          Subject: [softrock40] Re: Can't null TX image

                           
                          Argh...I spent all day doing basic checks with a multimeter. No shorts/bridges that I can find in the TX chain. Are there some more advanced tests I can do?
                        • warrenallgyer
                          Let s see if I can post on this subject without messing up again. One more advanced test that I have used to diagnose transmission problems is to transmit
                          Message 12 of 18 , May 18, 2014
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                            Let's see if I can post on this subject without messing up again.

                            One more advanced test that I have used to diagnose transmission problems is to transmit computer to computer. One computer running HDSDR in transmit, connected Line Out to Line In on a second computer running HDSDR on receive. This allows you to see the signal as it would be received and will quickly show if both I and Q are present and in the proper phase.

                            This will eliminate the software, the sound card and the sound control panel as possible causes.

                            Warren Allgyer
                            9V1TD
                          • ugless
                            Ok, I used a scope and found something very weird: the left and right channels are shorted together, but ONLY when the cable is plugged into the ensemble. If I
                            Message 13 of 18 , May 18, 2014
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                              Ok, I used a scope and found something very weird: the left and right channels are shorted together, but ONLY when the cable is plugged into the ensemble.

                              If I disconnect both ends of the cable, the left and right channels are not shorted together. If I plug one end into the sound card, they are not shorted together. If I leave it unplugged from the radio, the jack left/right are not shorted together. If I plug it into the radio (whether or not the sound card end is plugged in), the two channels short.

                              Is this a bad jack?
                            • Alan
                              Original Message ----- Subject: [softrock40] Re: Can t null TX image ... Use a ohmmeter. With nothing plugged into the Softrock Line Out is there a short at
                              Message 14 of 18 , May 18, 2014
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                                Original Message -----
                                Subject: [softrock40] Re: Can't null TX image


                                > Ok, I used a scope and found something very weird: the left and right channels are shorted together, but ONLY when the cable is
                                > plugged into the ensemble.
                                >
                                > If I disconnect both ends of the cable, the left and right channels are not shorted together. If I plug one end into the sound
                                > card, they are not shorted together. If I leave it unplugged from the radio, the jack left/right are not shorted together. If I
                                > plug it into the radio (whether or not the sound card end is plugged in), the two channels short.
                                >
                                >
                                > Is this a bad jack?
                                >

                                Use a ohmmeter.
                                With nothing plugged into the Softrock "Line Out" is there a short at the jack? Between the tracks that go to C5/6 and C4/C7.
                                I guess you are saying there is not until you put a plug into it?
                                Of this is the case then it looks like a faulty socket.

                                If there is a short at all times then it still could be the socket or a bridge, even a whisker not etched from the board.

                                73 Alan G4ZFQ
                              • Tony Parks
                                Could be... I have been testing jacks for this fault for the last few months prior to using them in filling kit orders. As I test a group of 20 jacks it is
                                Message 15 of 18 , May 19, 2014
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                                  Could be... I have been testing jacks for this fault for the last few months prior to using them in filling kit orders.  As I test a group of 20 jacks it is not unusual to find one with this fault. 

                                  If anyone needs a jack please contact me directly and I will send one at no charge.
                                  --
                                  Tony Parks
                                  kb9yig@...
                                  http://fivedash.com
                                  


                                  On Sun, 2014-05-18 at 20:50 -0700, rocketman768@... [softrock40] wrote:
                                   
                                  Ok, I used a scope and found something very weird: the left and right channels are shorted together, but ONLY when the cable is plugged into the ensemble.



                                  If I disconnect both ends of the cable, the left and right channels are not shorted together. If I plug one end into the sound card, they are not shorted together. If I leave it unplugged from the radio, the jack left/right are not shorted together. If I plug it into the radio (whether or not the sound card end is plugged in), the two channels short.


                                  Is this a bad jack?
                                • yl2qn_andy
                                  Hi, The same problem was with my build of RXTX. After some time of use (two months or three) I got similar problem. The problem was a bad jacks. My solution
                                  Message 16 of 18 , May 19, 2014
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                                    Hi,

                                    The same problem was with my build of RXTX. After some time of use (two months or three) I got similar problem. The problem was a bad jacks. My solution was to remove jacks at all and solder cables.

                                    I have a lot of issues with RX and TX come from bad cables and bad jacks. My final solutions (not situated for all) - remove sound card PCB from box and mount near RXTX PCB and connect without jacks with minimal length cables. After this I'm completely forget about any issues with ground loops, connect/no connect, phase/level settings etc.

                                    Regards,
                                    Andy - YL2QN  
                                     
                                  • ugless
                                    Got the new jack from Tony, put it in, and everything works!
                                    Message 17 of 18 , May 23, 2014
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                                      Got the new jack from Tony, put it in, and everything works!
                                    • MIKE DURKIN
                                      Good deal ... To: softrock40@yahoogroups.com From: softrock40@yahoogroups.com Date: Fri, 23 May 2014 14:29:17 -0700 Subject: [softrock40] Re: Can t null TX
                                      Message 18 of 18 , May 23, 2014
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                                        Good deal ...


                                        To: softrock40@yahoogroups.com
                                        From: softrock40@yahoogroups.com
                                        Date: Fri, 23 May 2014 14:29:17 -0700
                                        Subject: [softrock40] Re: Can't null TX image

                                         
                                        Got the new jack from Tony, put it in, and everything works!
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