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69631Re: [softrock40] Re: Bad chip?

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  • MICHAEL TALLENT
    Oct 31, 2012
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      You really want a low noise op-amp for this application as it will determine
      the noise floor of your receiver. The data sheet you linked looks like
      nothing special, so you will not get the performance that these receivers
      are capable of.

      Mike T W6MXV

      ----- Original Message -----
      From: "wfahle" <billfahle@...>
      To: <softrock40@yahoogroups.com>
      Sent: Wednesday, October 31, 2012 12:31 PM
      Subject: [softrock40] Re: Bad chip?


      > Well NOW it's the chip for sure. In an attempt to remove the IC to check
      > voltages and such, the green covering began to burn through exposing the
      > copper traces beneath. So I got out the clippers and clipped it loose from
      > the board, so that I could remove each lead individually. This worked, but
      > it tore up some of the pads in the process. I intend to replace it with
      > this chip because it is available locally (and I don't think going SMT
      > again is going to make life any easier):
      > http://www.nteinc.com/specs/700to799/pdf/nte778a.pdf
      >
      > --- In softrock40@yahoogroups.com, "wfahle" <billfahle@...> wrote:
      >>
      >> Ok, I pulled R16, and it still reads 5v at pin 1. R16 measures out at 10k
      >> as it should, but with it pulled there is very little voltage at pin 2.
      >> The current, since I can now measure it, across R16 is .24mA. The votage
      >> at pin 7 doesn't change either; it's still almost zero. The others
      >> besides 2 are unchanged. Pin 2 goes almost to zero vs. the 2.5 it had
      >> been reading. I guess R16 becomes part of a voltage divider under the
      >> circumstances; I don't understand circuits this complex. So I will try to
      >> unseat U6 and see if there is a solder bridge under it from 1 to 8 or
      >> something (they are across from each other).
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