Bias meters

[Paul P]

Last year I picked up a couple of NOS analog 0-50ma Triplett panel meters off ebay.

Is there an easy way to put together a tool using them to measure the output
tube currents to set the bias ?

I'm aware of the usual methods of bias adjustment, I just think it would be
cool to have two analog panel meters show me what's going on.

Could I just stick one of these meters between the output tube's cathode (resistor)
and ground ? Could I leave it there ? It would be kind of neat to have two
meters permanently mounted on my chassis if there was enough room,
which there isn't, like on some radio equipment.

I don't really know what kind of meters these things are apart from them
having scales reading in ma. Inside the meters there is a small wire coiled
into a few loops between both terminals.

Paul P

[Amp Kat]

It should work like that but most amps draw more than 50ma so you'd peg out not capturing all of the current. Usally 100 ma's is normal for most 50 to 100 watters.

[Enzo]

But you could shunt them, which is how they up the scales on meters anyway.

[Paul P]

I was originally thinking of inserting these meters using shorting phone jacks
in the cathode circuit like I've seen in old hi-fi amp schematics. I think 50ma
would be ok with 6v6s which are supposed to draw somewhere around 30ma
at 400 volts (?). Using one meter per tube, btw.

I've since learned about tip jacks (connected to the 1 ohm resistors) which
seems a better way to go. At least no one will be able to plug a speaker
into the cathode circuit.

Paul P

[Old Tele man]

I think 50ma would be ok with 6v6s which are supposed to draw somewhere around 30ma at 400 volts (?).
Paul P

...that's at IDLE, but maximum current can be 5X to 6X those values.