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Re: Signalink USB and WSJT - PTT delay causes hot start - any fix?

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  • Roger Kendall
    Hi Bill, I have a not dissimilar setup here with SignaLink USB,TX Linear Amp, Masthead RX amp etc. The basic problem is that with the SignaLink interface the
    Message 1 of 4 , Apr 8, 2011
      Hi Bill,
          I have a not dissimilar setup here with SignaLink USB,TX Linear Amp, Masthead RX amp etc. The basic problem is that with the SignaLink interface the initiation of the transmitter PTT is achieved by recognition of the presence of an AF tone(s) in the interface hence you cannot begin the consequent sequencing until a PTT signal is available from the SignaLink interface.Using the standard (supplied) interface cable to connect to the transmitter will always key the transmitter immediately unless you have some other sequencer that you can interpose between the interface and the TX to delay application of the PTT signal until switching of the other devices (linear etc)
          Ideally you need to ensure that the TX is last to be switched so no RF can be generated until all other devices in the chain have had time to reach transmit mode.(and vice versa when returning to a RX state) The majority of modern electro-mechanical relays seem to have a switching time of 10 to 15 milliseconds whereas the TX is likely to be much less resulting in the hot-switching  with its undesirable consequences.
          It is a good idea to draw a sketch plan of the system and decide which devices can be switched concurrently, sequentially, which should be mutually exclusive (or inclusive) and which require a delay mechanism. You need to do this for both RXto TX and again for TX to RX. I did this and so far have avoided "killing" any of the devices!!
       
                  Roger, G8BNE
    • Al WA4EWV
      Good Morning: I am including moon-net, wsjtgroup and Roger (G8BNE) email in this thread. I have opened the cable from the sequencer to the radio and brought
      Message 2 of 4 , Apr 8, 2011

        Good Morning:

        I am including moon-net, wsjtgroup and Roger (G8BNE) email in this thread.

         

        I have opened the cable from the sequencer to the radio and brought out the PTT wire.

        I cut the wire, and routed the PTT of the SignaLink to the sequencer.

        The output of the sequencer goes to the PTT of the radio.

         

        I have a block diagram of this if anyone wants it.

         

        I hope this helps.

        AL

        WA4EWV

         

         

         

         

         

         

         

        Hi Bill,

            I have a not dissimilar setup here with SignaLink USB,TX Linear Amp, Masthead RX amp etc. The basic problem is that with the SignaLink interface the initiation of the transmitter PTT is achieved by recognition of the presence of an AF tone(s) in the interface hence you cannot begin the consequent sequencing until a PTT signal is available from the SignaLink interface. Using the standard (supplied) interface cable to connect to the transmitter will always key the transmitter immediately unless you have some other sequencer that you can interpose between the interface and the TX to delay application of the PTT signal until switching of the other devices (linear etc)

            Ideally you need to ensure that the TX is last to be switched so no RF can be generated until all other devices in the chain have had time to reach transmit mode.(and vice versa when returning to a RX state) The majority of modern electro-mechanical relays seem to have a switching time of 10 to 15 milliseconds whereas the TX is likely to be much less resulting in the hot-switching  with its undesirable consequences.

            It is a good idea to draw a sketch plan of the system and decide which devices can be switched concurrently, sequentially, which should be mutually exclusive (or inclusive) and which require a delay mechanism. You need to do this for both RXto TX and again for TX to RX. I did this and so far have avoided "killing" any of the devices!!

         

                    Roger, G8BNE

         

         

        From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of billdz.geo
        Sent: Friday, April 08, 2011 6:29 AM
        To: wsjtgroup@yahoogroups.com
        Subject: [wsjtgroup] Signalink USB and WSJT - PTT delay causes hot start - any fix?

         

         

        Hello,

        I'm trying to use Signalink USB with WSJT on 2 meters with a kilowatt amp and a mast-mounted preamp. The problem is, there seems to be a delay before the PTT circuitry in the Signalink triggers the PTT circuitry in the rig and sequencer. By the time the rig's PTT is activated, the WSJT tones have already started, which means a hot start of the amplifier and the preamp relays, which is bad.

        Is there any way to prevent this PTT delay? I have never noticed it with any other interface.

        73, Bill NZ5N

      • Bill Dzurilla
        Roger and Al, thanks for the replies.  I think the problem is that the Signalink has a VOX-activated PTT command.  As Roger put it, the initiation of the
        Message 3 of 4 , Apr 8, 2011
          Roger and Al, thanks for the replies.  I think the problem is that the Signalink has a VOX-activated PTT command.  As Roger put it, "the initiation of the transmitter PTT is achieved by recognition of the presence of an AF tone(s) in the interface hence you cannot begin the consequent sequencing until a PTT signal is available from the SignaLink interface."

          I believe this VOX-type PTT makes the Signalink USB dangerous to use for EME, MS, or in any other type of application involving an amp or preamp.  We want the amp and the preamp to be fully switch into transmit mode BEFORE the tones start.  Even if we use a second sequencer between the Signalink output and the rig's PTT input, as Roger suggested, or if we
          open the cable from the sequencer to the radio and bring out the PTT wire to the PTT of the SignaLink, as Al suggested, the problem remains: the tones will have started BEFORE sequencing is completed, the power amp will hot start, and the preamp relays will hot switch. 

          As the WSJT tones do not start for a half second after the program sends the TX command, there is no problem as long as sequencing begins when WSJT sends the TX command and not when the tones begin.

          Everything worked fine with my old Donner interface, but I had hoped to replace it with the Signalink USB, which is said to have a superior sound card that makes for better decoding.  But unless there is some way to get the Signalink to activate PTT before the tones start (and apparently there is not), I will put the Signalink back on the shelf and use the Donner.

          Perhaps other Signalink models do not use VOX-type PTT?  It seems a lot of EMEers and ping jockeys use Signalink interfaces, perhaps different models than the USB.

          73, Bill NZ5N

          --- On Fri, 4/8/11, Al WA4EWV <wa4ewv@...> wrote:

          From: Al WA4EWV <wa4ewv@...>
          Subject: [Moon-net GG] Signalink USB and WSJT - PTT delay causes hot start - any fix?
          To: "'billdz.geo'" <billdz.geo@...>, wsjtgroup@yahoogroups.com
          Cc: "'Moon-Net'" <moon-net@...>, "'Roger Kendall'" <r.kendall@...>
          Date: Friday, April 8, 2011, 9:52 AM

          Good Morning:

          I am including moon-net, wsjtgroup and Roger (G8BNE) email in this thread.

           

          I have opened the cable from the sequencer to the radio and brought out the PTT wire.

          I cut the wire, and routed the PTT of the SignaLink to the sequencer.

          The output of the sequencer goes to the PTT of the radio.

           

          I have a block diagram of this if anyone wants it.

           

          I hope this helps.

          AL

          WA4EWV

           

           

           

           

           

           

           

          Hi Bill,

              I have a not dissimilar setup here with SignaLink USB,TX Linear Amp, Masthead RX amp etc. The basic problem is that with the SignaLink interface the initiation of the transmitter PTT is achieved by recognition of the presence of an AF tone(s) in the interface hence you cannot begin the consequent sequencing until a PTT signal is available from the SignaLink interface. Using the standard (supplied) interface cable to connect to the transmitter will always key the transmitter immediately unless you have some other sequencer that you can interpose between the interface and the TX to delay application of the PTT signal until switching of the other devices (linear etc)

              Ideally you need to ensure that the TX is last to be switched so no RF can be generated until all other devices in the chain have had time to reach transmit mode.(and vice versa when returning to a RX state) The majority of modern electro-mechanical relays seem to have a switching time of 10 to 15 milliseconds whereas the TX is likely to be much less resulting in the hot-switching  with its undesirable consequences.

              It is a good idea to draw a sketch plan of the system and decide which devices can be switched concurrently, sequentially, which should be mutually exclusive (or inclusive) and which require a delay mechanism. You need to do this for both RXto TX and again for TX to RX. I did this and so far have avoided "killing" any of the devices!!

           

                      Roger, G8BNE

           

           

          From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of billdz.geo
          Sent: Friday, April 08, 2011 6:29 AM
          To: wsjtgroup@yahoogroups.com
          Subject: [wsjtgroup] Signalink USB and WSJT - PTT delay causes hot start - any fix?

           

           

          Hello,

          I'm trying to use Signalink USB with WSJT on 2 meters with a kilowatt amp and a mast-mounted preamp. The problem is, there seems to be a delay before the PTT circuitry in the Signalink triggers the PTT circuitry in the rig and sequencer. By the time the rig's PTT is activated, the WSJT tones have already started, which means a hot start of the amplifier and the preamp relays, which is bad.

          Is there any way to prevent this PTT delay? I have never noticed it with any other interface.

          73, Bill NZ5N

          --
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