I was messing around with some multimeters here and noticed something while setting the bias on a tube amp I have in the basement with exposed tubes and is grounded thru the chassis and runs on a two prong plug.
First I had a non-contact voltage detector close to the amp.... the thing lights up within a foot of the amplifier. I suppose I understand that as there are exposed tubes.
I also noticed that there is .4 VAC (point 4 volts miniscule) between the chassis of the amp and the grounded conduit of the electrical system.
This was seen on a cheapo harbor freight multimeter. Thinking that this was phantom voltage I tried the two real multimeter I have. Using a fluke with True RMS which usually does not show phantom voltage when using on house wiring I also get the .4 VAC. Now it gets strange.
The other multimeter has a amperage clamp on it and is not true rms. Without the leads even touching either the amp or the grounded conduit the voltage started to creep up to 3VAC with the multimeter held over the amplifier. When I touched the probes to the chassis and the ground the multimeter, still be held over the amp, it creeped to over 275VAC!!!
I assume phantom voltage. I also touched the chassis and the ground pipe barefoot on cement floor and I am still alive so I am wondering.... is this just phantom voltage caused by the RF interference or something?
The fluke however showed .4 VAC chassis to house ground none the less... is that miniscule amount something to be concerned about that the amp has a flakey ground or something?
First I had a non-contact voltage detector close to the amp.... the thing lights up within a foot of the amplifier. I suppose I understand that as there are exposed tubes.
I also noticed that there is .4 VAC (point 4 volts miniscule) between the chassis of the amp and the grounded conduit of the electrical system.
This was seen on a cheapo harbor freight multimeter. Thinking that this was phantom voltage I tried the two real multimeter I have. Using a fluke with True RMS which usually does not show phantom voltage when using on house wiring I also get the .4 VAC. Now it gets strange.
The other multimeter has a amperage clamp on it and is not true rms. Without the leads even touching either the amp or the grounded conduit the voltage started to creep up to 3VAC with the multimeter held over the amplifier. When I touched the probes to the chassis and the ground the multimeter, still be held over the amp, it creeped to over 275VAC!!!
I assume phantom voltage. I also touched the chassis and the ground pipe barefoot on cement floor and I am still alive so I am wondering.... is this just phantom voltage caused by the RF interference or something?
The fluke however showed .4 VAC chassis to house ground none the less... is that miniscule amount something to be concerned about that the amp has a flakey ground or something?