Looking at the discussion below, would it not be a good idea to replace said
regulator with a 7809 regulator?
Gary
W0DVN
>
>
>
> Greetings:
>
> I am working on an Argonaut 505.
>
> The 9 MHz BFO is low in frequency, cannot be pulled in. This resulted in
> severely reduced output power in CW or Tune since the carrier is now out of
> the filter passband.
>
> My question is, has anyone actually measured the 9 volt line in one of these?
>
> The line is nominally tagged as “9 volts”, but all of the test points in the
> manual call out 9.5 volts.
>
> This particular radio measures 8.0 volts on this line, too low, in my
> estimation, and this could account for the frequency error in the BFO.
>
> The regulator is pretty ingeniously simple and cheap - it actually has error
> measurement via Q8, whose base is established by the difference between the
> supply output voltage and the base of Q8. Q8 then controls the pass element,
> Q7, to hold the “9 volt” line constant.
>
> However, it seems to me that a change in the gain of Q8 would affect the
> output voltage…
>
> Gary
>
> W0DVN
>
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