[ARC5] Brian's deaf set

[Leslie Smith]

  Hello Neil,

  I got a message (e-mail) from Brian.  He connected his signal
  generator to the grid of the 12A6 and discovered that the AF generator
  was very sick.   The 12A6 has a voltage gain of 3.  ie if he feeds in
  1 volt he gets 3 volts out (on the primary).  I think the should get a
  gain of 10 to 28 from that stage.  (That's my guess.)  I think 5V on
  the grid should give 70V RMS.  That makes a gain of 14 or 15.   He
  replaced the tube (he mentioned that).  The voltage on the screen is
  ok, so that doesn't leave much except the cathode bias R-C and the
  plate circuit.

Brain replaced some caps in the sig. gen. but hasn't got back to the
receiver yet.

My guess:  There is a problem with the AF output transformer or (just as
likely) the SM capacitor across the primary winding.  I found the SM cap
in one of my sets had 350 ohms resistance.  That really slows down the
signal across the output!!

Work on my shed is progressing.  I'm about to put the trench mesh in
place.



   73 de Les Smith
   vk2bcu at operamail.com



On Tue, Oct 11, 2016, at 14:28, AKLDGUY . wrote:
> So what was the outcome of Brian's deaf set? Did he find the fault?
>
> 73 de Neil ZL1ANM
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