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On Thu, 23 Feb 2023 11:37:29 -0800, "Iowa59 Ham" <iowa59ham@...> wrote:
I have a lot of chaos with the voltages on this unit and one item I am stumped on is the R57 shunt > picture + schematic attached.
Why would the voltage be the same on both sides? Unless then repealed Ohms law I should have a lower voltage on one end?
Its a 5.1 Ohm that measures about 6.1 and I get 3mV across it power on. DC Voltage is -67 on both sides with T2 or T1&T2 on.
What type of meter are you using?
If it doesn't have a high input impedance, it might be loading the circuit
slightly on the other end of the resistor. The older Radio Shack meters had a
low input impedance compared to most of today's or the old vacuum tube meters.
Or you might not be noticing a decimal value difference on a reading. If you
measure a voltage drop across it, then a meter should see that difference
between the two measurement points to ground, also. One reading should be either
-66.007 or -67.003 volts, but I wonder if your meter will let you see such small
differences. (Unless you mean -67 mV.)
The 3 mV difference means that current is flowing and the resistor isn't shorted
somehow internally. What's the current you measure? Does it agree with the 3 mV
drop and resistor value you measure with one leg disconnected?
That's where I'd start.
Donald KX8K
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