[Amps] plate voltage meter shunt

[Bill Turner]

ORIGINAL MESSAGE: 
On Sat, 3 Nov 2012 22:51:14 -0700, W7RY wrote:

>And the voltage is not the same 
>across each cap. The one with the metering circuit has lower voltage across 
>it.

REPLY: 
That would be true if the metering circuit was in parallel with the bleeder
resistor, but it is not. It's in series, and the effect is to raise the voltage,
not lower it. 

However, if you do the math you'll see the amount of voltage rise is very small
because the meter resistance is very small compared to the value of the bleeder
resistor. 

For example in my own homebrew amp using Simpson Century series meters, the 0-1
mA meter has a resistance of 43 ohms. This is in series with the bleeder
resistor across the bottom cap which is 100k ohms. Since the total bleeder
current is about 6 mA, 5 mA is shunted around the meter by the calibration
resistor, so the net resistance added to the bleeder string is less than ten
ohms out of a total of 800,000 ohms. 

It's not an issue. 

73, Bill W6WRT