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Re: High voltages and other problems phase 5-6

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  • ralph.dahlstrom
    Yeah, I awoke this morning thinking it was miraculous that a little choke could isolate the voltages so nicely. 437.7K! I replaced the inductor and got proper
    Message 1 of 6 , May 2, 2011
      Yeah, I awoke this morning thinking it was miraculous that a little choke could isolate the voltages so nicely. 437.7K! I replaced the inductor and got proper voltages on IC1R, but now I have to figure out the op-amps. The separate 100Ω resistors between twelve volts and pins 7 seem unlikely, and they measure correct to within a few ohms, but there is supply voltage on one side and 13.33V on the other, just as appears at pin 7 on each op amp. If 100Ω is supposed to drop the voltage more, it doesn't, and it seems that the problem, to be common to both op amps, should be elsewhere. I measured the voltage between R6R and R7R and there I get 6.9 V, just as between R15 and R16. Of course this is what I get on pin 5 of each op-amp, and it represents properly divided 13.8V. So what does one have to do to get 5.05V, other than run the G59 off 10.1 V?

      I can't imagine two bad op-amps, and I think I am missing something common to the two, but inspection does not show me what I am missing.

      --- In GenesisRadio@yahoogroups.com, "Bruce Greenleaf KF1Z" <kf1z@...> wrote:
      >
      > measure resistance of L1R ( power off of course.
      >
      > Bruce
      > kf1z
      >
      >
      > From: ralph.dahlstrom
      > Sent: Monday, May 02, 2011 12:47 AM
      > To: GenesisRadio@yahoogroups.com
      > Subject: [GenesisRadio] High voltages and other problems phase 5-6
      >
      >
      > Well, I have looked at this thing 'til I am blue in the face. the only place I can see contributing my 4.90 V would be pin 14 of IC1R, where the reading is actually 5.00V. When I tested the receiver supply voltage before building the receiver it was 2.50V and remains so, but at the supply side of L1R it remains 2.5 and at the other end it is 4.90. So I must have had either two defective 74LVC4066 devices or they both fried from static electricity before installation. I guess a wrist strap is only as good as its ground. I really can't see any other place for the problem to originate. It would explain, I think, why I don't see much activity on the ham bands, though I occasionally find something. I have only a wire in the shack for an antenna, but I occasionally find a signal on it.. I guess I will have to chase down a replacement quad switch - actually two now!
      >
      > I have sound card problems as well. That I will deal with tomorrow. It is not the settings, but rather something, maybe from the cooling fans, in the computer. I will choke them and see if that helps. Still open to suggestions.
      > Ralph, K5RD
      >
      >
      >
      >
      >
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    • Bruce Greenleaf KF1Z
      Good.... ! Now, the opamps. I see nothing wrong with the voltages... Pin 5 of each opamp is supposed to be 6 volts, ONLY if you have a 12vdc supply. if you use
      Message 2 of 6 , May 2, 2011
        Good.... !
         
         
        Now, the opamps.
         
        I see nothing wrong with the voltages...
         
        Pin 5 of each opamp is supposed to be 6 volts, ONLY if you have a 12vdc supply.
         
        if you use a 13.8 volt supply, you’re going to see about 6.9 vdc on pins 5 of the opamps.
         
        Time to move on!
         
        Bruce
         
         
        Sent: Monday, May 02, 2011 1:44 PM
        Subject: [GenesisRadio] Re: High voltages and other problems phase 5-6
         
         

        Yeah, I awoke this morning thinking it was miraculous that a little choke could isolate the voltages so nicely. 437.7K! I replaced the inductor and got proper voltages on IC1R, but now I have to figure out the op-amps. The separate 100&#937; resistors between twelve volts and pins 7 seem unlikely, and they measure correct to within a few ohms, but there is supply voltage on one side and 13.33V on the other, just as appears at pin 7 on each op amp. If 100&#937; is supposed to drop the voltage more, it doesn't, and it seems that the problem, to be common to both op amps, should be elsewhere. I measured the voltage between R6R and R7R and there I get 6.9 V, just as between R15 and R16. Of course this is what I get on pin 5 of each op-amp, and it represents properly divided 13.8V. So what does one have to do to get 5.05V, other than run the G59 off 10.1 V?

        I can't imagine two bad op-amps, and I think I am missing something common to the two, but inspection does not show me what I am missing.

        --- In mailto:GenesisRadio%40yahoogroups.com, "Bruce Greenleaf KF1Z" <kf1z@...> wrote:

        >
        > measure
        resistance of L1R ( power off of course.
        >
        > Bruce
        >
        kf1z
        >
        >
        > From: ralph.dahlstrom
        > Sent: Monday, May
        02, 2011 12:47 AM
        > To:
        href="mailto:GenesisRadio%40yahoogroups.com">mailto:GenesisRadio%40yahoogroups.com
        > Subject: [GenesisRadio] High voltages and other problems phase
        5-6
        >
        >
        > Well, I have looked at this thing 'til I am blue
        in the face. the only place I can see contributing my 4.90 V would be pin 14 of IC1R, where the reading is actually 5.00V. When I tested the receiver supply voltage before building the receiver it was 2.50V and remains so, but at the supply side of L1R it remains 2.5 and at the other end it is 4.90. So I must have had either two defective 74LVC4066 devices or they both fried from static electricity before installation. I guess a wrist strap is only as good as its ground. I really can't see any other place for the problem to originate. It would explain, I think, why I don't see much activity on the ham bands, though I occasionally find something. I have only a wire in the shack for an antenna, but I occasionally find a signal on it.. I guess I will have to chase down a replacement quad switch - actually two now!
        >
        > I have sound card
        problems as well. That I will deal with tomorrow. It is not the settings, but rather something, maybe from the cooling fans, in the computer. I will choke them and see if that helps. Still open to suggestions.
        > Ralph,
        K5RD
        >
        >
        >
        >
        >
        >
        >
        >
        > =======
        > Email scanned by PC Tools - No viruses or spyware
        found.
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        http://www.pctools.com
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