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Re: [GenesisRadio] TX/RX Relay

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  • Bruce KF1Z
    Could be that the relay is stuck. Measure it with an ohmmeter to test, don t rely on hearing . Just disconnect the RF from G59 to GPA10 first, and check
    Message 1 of 19 , Nov 30, 2012
      Could be that the relay is stuck.
       
      Measure it with an ohmmeter to test, don't rely on 'hearing'.  Smile
      Just disconnect the RF from G59 to GPA10 first, and check continuity in RX/TX on the contacts
       
      If there is bias voltage at the driver and final when +5 is at the TX pin on the 4 pin jack, then there is no problem with  the CD4028 or ULN2003.
      And that means the relay coil must be ok.
      Well, turns could be shorted actually,
       
      So measure the resistance of the coil too ( with no power to GPA10 board)
       
      Bruce
      kf1z
       
       
       
       
      From: titZelbop
      Sent: Friday, November 30, 2012 10:56 PM
      Subject: [GenesisRadio] TX/RX Relay
       
       

      Hello,

      I am assembling the GPA 10 power amplifier board and I seem to have a problem with the TX/RX relay. It seems that I dont hear the contacts close when I apply +5V to the TX/RX pin, although the driver stage powers up when I do this. I've tried swapping out the ULN chips as well, no change. All other relays on the board seem to work.

      Any help would be appreciated.

      Stephen

    • titZelbop
      Hi, I confirmed that with the DMM that the contacts are not switching when +5V is applied to the TX/RX pin, although the current draw does increase by about
      Message 2 of 19 , Dec 2, 2012
        Hi,

        I confirmed that with the DMM that the contacts are not switching when +5V is applied to the TX/RX pin, although the current draw does increase by about 100mA. Resistance of the coil (with the power off) is about 650 ohms which is in line with the datasheet specifications.

        When +5V is applied I measure 12V across the relay coil. When no voltage is applied I measure ~1.8 volts which is above the minimum drop-out voltage for the relay. Is it possible that this is the problem?
      • Bruce KF1Z
        Well, this is easy to tell..... With NO +5 to TX pin on 4 pin connector...... ] Are the relay contacts in their on or off position? If they are in the on
        Message 3 of 19 , Dec 2, 2012
          Well, this is easy to tell.....
           
          With NO +5 to TX pin on 4 pin connector......
          ]
          Are the relay contacts in their on or off position?
           
          If they are in the on position, do they switch to the off position when power is disconnected from the board?
           
          Bruce
           
           
          From: titZelbop
          Sent: Sunday, December 02, 2012 5:22 PM
          Subject: [GenesisRadio] Re: TX/RX Relay
           
           

          Hi,

          I confirmed that with the DMM that the contacts are not switching when +5V is applied to the TX/RX pin, although the current draw does increase by about 100mA. Resistance of the coil (with the power off) is about 650 ohms which is in line with the datasheet specifications.

          When +5V is applied I measure 12V across the relay coil. When no voltage is applied I measure ~1.8 volts which is above the minimum drop-out voltage for the relay. Is it possible that this is the problem?

        • titZelbop
          Hi Bruce, Checking with the DMM, the relay contacts are in the same position with +5V on pin 4, 0V on pin 4 and with the board off. I thought it s maybe the
          Message 4 of 19 , Dec 2, 2012
            Hi Bruce,

            Checking with the DMM, the relay contacts are in the same position with +5V on pin 4, 0V on pin 4 and with the board off. I thought it's maybe the relay, so I desoldered in and tried a different one. Same issue. I can see that the voltage across the relay coil toggles between ~1.5V and ~12V but it does not switch.

            Any other suggestions?

            Stephen
          • Bruce KF1Z
            If you disconnect power form the board completely. The relay contacts do no change position? not even with the new relay? bruce From: titZelbop Sent: Monday,
            Message 5 of 19 , Dec 3, 2012
              If you disconnect power form the board completely.
               
              The relay contacts do no change position?  not even with the new relay?
               
              bruce
               
               
              From: titZelbop
              Sent: Monday, December 03, 2012 12:50 AM
              Subject: [GenesisRadio] Re: TX/RX Relay
               
               

              Hi Bruce,

              Checking with the DMM, the relay contacts are in the same position with +5V on pin 4, 0V on pin 4 and with the board off. I thought it's maybe the relay, so I desoldered in and tried a different one. Same issue. I can see that the voltage across the relay coil toggles between ~1.5V and ~12V but it does not switch.

              Any other suggestions?

              Stephen

            • titZelbop
              Hi Bruce, Yes that appears to be the case. I ve been poking around trying to see what the matter might be but I m running out of leads.
              Message 6 of 19 , Dec 3, 2012
                Hi Bruce,

                Yes that appears to be the case. I've been poking around trying to see what the matter might be but I'm running out of leads.
              • Bruce KF1Z
                Well, It just does not make any sense. I mean, I can understand if the relay is not dropping out when power is applied to the board. But in that case it would
                Message 7 of 19 , Dec 3, 2012
                  Well,
                  It just does not make any sense.
                   
                   
                   
                  I mean, I can understand if the relay is not dropping out when power is applied to the board.
                  But in that case it would drop out when power is disconnected.
                   
                  Maybe it never turns ON at all?
                   
                  That could ( almost MUST ) be the case.
                   
                   
                  Please measure at SV2PA ( 3 wire connector behind relay)
                   
                  Reference pin 1 as the pin closest to REL2C ( the relay that IS installed)
                   
                  Measure DC voltage referenced to ground, at each of the 3 pins, in RX, then in TX
                   
                  And let me know what those are.
                   
                  Bruce
                   
                   
                  From: titZelbop
                  Sent: Monday, December 03, 2012 1:06 PM
                  Subject: [GenesisRadio] Re: TX/RX Relay
                   
                   

                  Hi Bruce,

                  Yes that appears to be the case. I've been poking around trying to see what the matter might be but I'm running out of leads.

                • Bruce KF1Z
                  Meant SV3PB , not PA bruce From: Bruce KF1Z Sent: Monday, December 03, 2012 1:20 PM To: GenesisRadio@yahoogroups.com Subject: Re: [GenesisRadio] Re: TX/RX
                  Message 8 of 19 , Dec 3, 2012
                    Meant SV3PB , not PA
                     
                    bruce
                     
                     
                    Sent: Monday, December 03, 2012 1:20 PM
                    Subject: Re: [GenesisRadio] Re: TX/RX Relay
                     
                     

                    Well,
                    It just does not make any sense.
                     
                     
                     
                    I mean, I can understand if the relay is not dropping out when power is applied to the board.
                    But in that case it would drop out when power is disconnected.
                     
                    Maybe it never turns ON at all?
                     
                    That could ( almost MUST ) be the case.
                     
                     
                    Please measure at SV2PA ( 3 wire connector behind relay)
                     
                    Reference pin 1 as the pin closest to REL2C ( the relay that IS installed)
                     
                    Measure DC voltage referenced to ground, at each of the 3 pins, in RX, then in TX
                     
                    And let me know what those are.
                     
                    Bruce
                     
                     
                    From: titZelbop
                    Sent: Monday, December 03, 2012 1:06 PM
                    Subject: [GenesisRadio] Re: TX/RX Relay
                     
                     

                    Hi Bruce,

                    Yes that appears to be the case. I've been poking around trying to see what the matter might be but I'm running out of leads.

                  • Bruce KF1Z
                    Geez.... I AM doing well..... SV2PB bruce From: Bruce KF1Z Sent: Monday, December 03, 2012 1:36 PM To: GenesisRadio@yahoogroups.com Subject: Re:
                    Message 9 of 19 , Dec 3, 2012
                      Geez....  I AM doing well.....
                       
                      SV2PB
                       
                      Smile
                       
                      bruce
                       
                       
                      Sent: Monday, December 03, 2012 1:36 PM
                      Subject: Re: [GenesisRadio] Re: TX/RX Relay
                       
                       

                      Meant SV3PB , not PA
                       
                      bruce
                       
                       
                      Sent: Monday, December 03, 2012 1:20 PM
                      Subject: Re: [GenesisRadio] Re: TX/RX Relay
                       
                       

                      Well,
                      It just does not make any sense.
                       
                       
                       
                      I mean, I can understand if the relay is not dropping out when power is applied to the board.
                      But in that case it would drop out when power is disconnected.
                       
                      Maybe it never turns ON at all?
                       
                      That could ( almost MUST ) be the case.
                       
                       
                      Please measure at SV2PA ( 3 wire connector behind relay)
                       
                      Reference pin 1 as the pin closest to REL2C ( the relay that IS installed)
                       
                      Measure DC voltage referenced to ground, at each of the 3 pins, in RX, then in TX
                       
                      And let me know what those are.
                       
                      Bruce
                       
                       
                      From: titZelbop
                      Sent: Monday, December 03, 2012 1:06 PM
                      Subject: [GenesisRadio] Re: TX/RX Relay
                       
                       

                      Hi Bruce,

                      Yes that appears to be the case. I've been poking around trying to see what the matter might be but I'm running out of leads.

                    • Bruce KF1Z
                      I am about ready to give up on myself... Too many conversations at once I guess. I appologize. The connector is SV3PB yes, SV3PB actually pin 3 should be
                      Message 10 of 19 , Dec 3, 2012
                        I am about ready to give up on myself...
                        Too many conversations at once I guess.
                         
                         
                        I appologize.
                         
                        The connector is SV3PB  yes, SV3PB
                         
                        actually pin 3 should be closest to the BNC connector.
                        But tell me which is which,.
                         
                         
                        I am sorry for my own confusion!
                         
                        I just checked again...  yes SV3PB
                         
                        Smile
                         
                        Bruce
                         
                         
                        Sent: Monday, December 03, 2012 1:37 PM
                        Subject: Re: [GenesisRadio] Re: TX/RX Relay
                         
                         

                        Geez....  I AM doing well.....
                         
                        SV2PB
                         
                        Smile
                         
                        bruce
                         
                         
                        Sent: Monday, December 03, 2012 1:36 PM
                        Subject: Re: [GenesisRadio] Re: TX/RX Relay
                         
                         

                        Meant SV3PB , not PA
                         
                        bruce
                         
                         
                        Sent: Monday, December 03, 2012 1:20 PM
                        Subject: Re: [GenesisRadio] Re: TX/RX Relay
                         
                         

                        Well,
                        It just does not make any sense.
                         
                         
                         
                        I mean, I can understand if the relay is not dropping out when power is applied to the board.
                        But in that case it would drop out when power is disconnected.
                         
                        Maybe it never turns ON at all?
                         
                        That could ( almost MUST ) be the case.
                         
                         
                        Please measure at SV2PA ( 3 wire connector behind relay)
                         
                        Reference pin 1 as the pin closest to REL2C ( the relay that IS installed)
                         
                        Measure DC voltage referenced to ground, at each of the 3 pins, in RX, then in TX
                         
                        And let me know what those are.
                         
                        Bruce
                         
                         
                        From: titZelbop
                        Sent: Monday, December 03, 2012 1:06 PM
                        Subject: [GenesisRadio] Re: TX/RX Relay
                         
                         

                        Hi Bruce,

                        Yes that appears to be the case. I've been poking around trying to see what the matter might be but I'm running out of leads.

                      • titZelbop
                        Hi Bruce, Taking pin 3 as the closest pin to the BNC connector, 12V applied to the circuit: No Voltage on Pin 4: 1: ~0V 2: ~12V 3: 10.5V +5V on Pin 4: 1: ~0V
                        Message 11 of 19 , Dec 3, 2012
                          Hi Bruce,

                          Taking pin 3 as the closest pin to the BNC connector, 12V applied to the circuit:

                          No Voltage on Pin 4:
                          1: ~0V
                          2: ~12V
                          3: 10.5V

                          +5V on Pin 4:
                          1: ~0V
                          2: ~12V
                          3: 1.05V

                          There is no issue with the relay that I took out of the circuit, I measured its drop in voltage to be about 8V and the drop out to be about 2V, contacts switch as expected. Other relays switch as expected when applying different combinations of 5V and 0V to the band select pins.

                          Stephen
                        • Bruce KF1Z
                          Pin 3 should drop to 0.7 v on TX. This may be the issue. I told you that the UNL2003 is good. well, may be wrong. Try measuring pin 13 on ULN 2003 in TX It
                          Message 12 of 19 , Dec 3, 2012
                            Pin 3 should drop to 0.7 v on TX.
                             
                            This may be the issue.
                             
                            I told you that the UNL2003 is good.
                             
                            well, may be wrong.
                             
                             
                            Try measuring pin 13 on ULN 2003 in TX
                             
                            It should be near 12v on RX, and drop to 0.7v on TX
                            ( measure pin 14 as well... though it is not in use)
                             
                            Measure resistance between on 13 of ULN2003 and pin 3 of SV3PB
                             
                             
                            If pin 13 drops to 0.7v, then there is a connection ( resistive) problem between ULN2003 and pin 3 of SV2PB
                             
                            Is ULN2003 in a socket?
                             
                            BRuce
                             
                             
                            From: titZelbop
                            Sent: Monday, December 03, 2012 3:09 PM
                            Subject: [GenesisRadio] Re: TX/RX Relay
                             
                             

                            Hi Bruce,

                            Taking pin 3 as the closest pin to the BNC connector, 12V applied to the circuit:

                            No Voltage on Pin 4:
                            1: ~0V
                            2: ~12V
                            3: 10.5V

                            +5V on Pin 4:
                            1: ~0V
                            2: ~12V
                            3: 1.05V

                            There is no issue with the relay that I took out of the circuit, I measured its drop in voltage to be about 8V and the drop out to be about 2V, contacts switch as expected. Other relays switch as expected when applying different combinations of 5V and 0V to the band select pins.

                            Stephen

                          • titZelbop
                            Hi Bruce, Yes ULNs are socketed. I ve swapped them with no change in behaviour. Do you think it is a bad socket?
                            Message 13 of 19 , Dec 3, 2012
                              Hi Bruce,

                              Yes ULNs are socketed. I've swapped them with no change in behaviour. Do you think it is a bad socket?
                            • titZelbop
                              Hi Bruce, It is the same as measured on pin 3 of the connector. I am measuring from the physical pin of the ULN. ~10.5V and ~1.05V. Measured a resistance of
                              Message 14 of 19 , Dec 3, 2012
                                Hi Bruce,

                                It is the same as measured on pin 3 of the connector. I am measuring from the physical pin of the ULN.

                                ~10.5V and ~1.05V.

                                Measured a resistance of < 0.1 Ohm between the actual pin on the ULN to the side of L1D that connects to pin 3. This should be the resistance of the path through the socket, board, ribbon cable and connectors.
                              • Bruce KF1Z
                                no, socket is fine, if you swapped devices and got the same result ( SOMETHING would have changed. According to the resistance I d say that is fine... My
                                Message 15 of 19 , Dec 3, 2012
                                  no, socket is fine, if you swapped devices and got the same result ( SOMETHING would have changed.
                                   
                                  According to the resistance I'd say that is fine...
                                   
                                   
                                  My supply is 13.7 volts.   you are using 12.0v  even ?
                                   
                                  Do you have a supply that is higher voltage that you can try?  ( most bench supplies are 13.6 )
                                   
                                  That drop on the relay may be right on the hairy edge with low supply voltage.
                                   
                                  Bruce
                                   
                                   
                                   
                                   
                                   
                                   
                                   
                                  From: titZelbop
                                  Sent: Monday, December 03, 2012 3:54 PM
                                  Subject: [GenesisRadio] Re: TX/RX Relay
                                   
                                   

                                  Hi Bruce,

                                  Yes ULNs are socketed. I've swapped them with no change in behaviour. Do you think it is a bad socket?

                                • Bruce KF1Z
                                  May be worth checking that R6C is a 1k . Though I m not sure that would make the difference... After supper, I ll check my pin 13/uln2003 I was thinking that
                                  Message 16 of 19 , Dec 3, 2012
                                    May be worth checking that R6C is a 1k .
                                    Though I'm not sure that would make the difference...
                                     
                                    After supper, I'll check my pin 13/uln2003   I was thinking that it "had" to be 0.7v  because it's just a transistor switch.
                                     
                                    very odd, in any case.
                                     
                                     
                                    Bruce
                                     
                                     
                                    Sent: Monday, December 03, 2012 4:47 PM
                                    Subject: Re: [GenesisRadio] Re: TX/RX Relay
                                     
                                     

                                    no, socket is fine, if you swapped devices and got the same result ( SOMETHING would have changed.
                                     
                                    According to the resistance I'd say that is fine...
                                     
                                     
                                    My supply is 13.7 volts.   you are using 12.0v  even ?
                                     
                                    Do you have a supply that is higher voltage that you can try?  ( most bench supplies are 13.6 )
                                     
                                    That drop on the relay may be right on the hairy edge with low supply voltage.
                                     
                                    Bruce
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                    From: titZelbop
                                    Sent: Monday, December 03, 2012 3:54 PM
                                    Subject: [GenesisRadio] Re: TX/RX Relay
                                     
                                     

                                    Hi Bruce,

                                    Yes ULNs are socketed. I've swapped them with no change in behaviour. Do you think it is a bad socket?

                                  • Bruce KF1Z
                                    Ok, yes, Pin 3 of SV3PB ( pin 13 of uln2003)... does indeed go to 0.69 v on TX. and 12.05 in RX ( with 13.76v on pin 2 ) So, that means I have 11.36v
                                    Message 17 of 19 , Dec 3, 2012
                                      Ok, yes,
                                       
                                      Pin 3 of SV3PB ( pin 13 of uln2003)...   does indeed go to 0.69 v on TX. and 12.05 in RX   ( with 13.76v on pin 2 )
                                       
                                      So, that means I have 11.36v across my relay in TX  ( 12.05 – 0.69 )
                                       
                                      Where you have 9.45v  ( 10.5 – 1.05 )
                                       
                                      Maybe this is enough difference......
                                       
                                       
                                      I THINK that if you try a higher supply voltage, you may be ok.....
                                       
                                       
                                       
                                      Sent: Monday, December 03, 2012 4:55 PM
                                      Subject: Re: [GenesisRadio] Re: TX/RX Relay
                                       
                                       

                                      May be worth checking that R6C is a 1k .
                                      Though I'm not sure that would make the difference...
                                       
                                      After supper, I'll check my pin 13/uln2003   I was thinking that it "had" to be 0.7v  because it's just a transistor switch.
                                       
                                      very odd, in any case.
                                       
                                       
                                      Bruce
                                       
                                       
                                      Sent: Monday, December 03, 2012 4:47 PM
                                      Subject: Re: [GenesisRadio] Re: TX/RX Relay
                                       
                                       

                                      no, socket is fine, if you swapped devices and got the same result ( SOMETHING would have changed.
                                       
                                      According to the resistance I'd say that is fine...
                                       
                                       
                                      My supply is 13.7 volts.   you are using 12.0v  even ?
                                       
                                      Do you have a supply that is higher voltage that you can try?  ( most bench supplies are 13.6 )
                                       
                                      That drop on the relay may be right on the hairy edge with low supply voltage.
                                       
                                      Bruce
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                      From: titZelbop
                                      Sent: Monday, December 03, 2012 3:54 PM
                                      Subject: [GenesisRadio] Re: TX/RX Relay
                                       
                                       

                                      Hi Bruce,

                                      Yes ULNs are socketed. I've swapped them with no change in behaviour. Do you think it is a bad socket?

                                    • titZelbop
                                      Hi, I worked with a colleague to figure out the problem. The relays that were shipped with this board appear to be these ones:
                                      Message 18 of 19 , Dec 3, 2012
                                        Hi,

                                        I worked with a colleague to figure out the problem. The relays that were shipped with this board appear to be these ones:

                                        http://www.datasheetcatalog.org/datasheets2/42/42032_1.pdf

                                        This is a POLARIZED RELAY as stated in the "Features" list, and we confirmed this by desoldering and testing one relay from the kit in isolation. We found that the contacts did not close unless the voltage was applied to the coil in the orientation shown in the datasheet.

                                        From looking at the schematic and tracing the PCB, we see that the voltage is applied to the coil of REL1C in the opposite orientation as specified in the datasheet. It seems that half of the band switching relays also have this issue.

                                        Can you please suggest a fix that does not involve desoldering all of the relays?

                                        Stephen
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