Re: 453 calibrator

Chuck Harris
 

No, you aren't missing anything. What Jeff was saying
is if BA is truly at ground, then you cannot have a signal
out your calibrator. It may appear to be grounded if you
use an ohmmeter that is on too high a scale... due to the
160, or so ohms that the circuit inherently has to ground.

-Chuck Harris

Mike Merigliano wrote:

The signal is not shorted to ground -- it goes through a 2.19K resistor in series
first, so there is no short. My Tek 453 has a calibrator signal, at specification. My
ohmeter and voltmeter check measurements between/around Q1274, point BA, R1274, and
point BB match what is on the schematic.

Maybe I am missing something.

On 5/9/2018 10:19 AM, Jeff Urban wrote:
On Wed, May 9, 2018 at 08:13 am, Mike Merigliano wrote:

There is no error here; BB is a ground point, and the emitter of Q1274 goes to
it via R1274 in series.
Then there can be no output at the calibrator terminal unless the whole thing
floats and has a separately isolated power supply. The signal would forever be
shorted to ground.

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