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Re: [GenesisRadio] Re: TX/RX Relay

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  • 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 1 of 19 , Dec 3, 2012
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      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 2 of 19 , Dec 3, 2012
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        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 3 of 19 , Dec 3, 2012
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          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 4 of 19 , Dec 3, 2012
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            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 5 of 19 , Dec 3, 2012
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              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 6 of 19 , Dec 3, 2012
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                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 7 of 19 , Dec 3, 2012
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                  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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