B&W 5100 PA tuning question...

[K1ZJH]

I'm not sure I'm reading the manual correctly.

What is the recommended grid current for the 6146 PA tubes?

Pete

[Joe Moore]

My manual says to load it up to 220ma as read with the meter switch
in the AMP. position.

[Joe Moore]

And the Grid to around 17mils.

[K1ZJH]

And the Grid to around 17mils.

Bingo!

Yeah, but isn't almost 8 mA grid #1 per tube way over the max ratings for a 6146??

That's what I read too. Or does the "metering reading" a relative scale type of indication?

Pete

[WQ9E]

One of the B&W 5100B's oddities is that it monitors the final screen instead of control grid current.  I believe it runs around 220 volts on the screen so 17 mils is approaching the maximum rating for a pair of 6146 tubes (2 watt screen dissipation per tube).  So 17 mils is safe but don't go way over this to keep the final tubes happy.

Rodger WQ9E

[K1ZJH]

Thanks Roger, that makes more sense. In many ways the manual is a train-wreck. Not very well organized or written. I'm still muddling my way through it.

Pete