bias

Smokebreak · Post by **Smokebreak** » Wed Dec 25, 2013 1:24 am

I'm working on a 50W 6L6 fixed bias and built my bias board for running off HT leg, before I realized the PT I'm gonna use has a 50V tap. I was just gonna change the 220K before reverse diode to 470r, or so, and use the 50V tap, but it got me thinking..Is there a reason why one way would be more advantageous than the other?

Andy Le Blanc · Post by **Andy Le Blanc** » Wed Dec 25, 2013 12:15 pm

less parts, no coupling cap, lower voltage means cheaper lower watt parts w/50v

martin manning · Post by **martin manning** » Wed Dec 25, 2013 1:42 pm

If this is a FW rectifier configuration the part count is about the same. True the first dropping resistor needs to be stout if the bias is taken from the HT. If the 50V tap is actually a separate winding (which is sometimes the case), that would reduce any asymmetry that might be created if bias is taken from one side of the HT winding.

Smokebreak · Post by **Smokebreak** » Wed Dec 25, 2013 2:54 pm

Sorry, yes FW ala Express. Thanks!

Firestorm · Post by **Firestorm** » Wed Dec 25, 2013 3:02 pm

If you ever decide to power scale the amp, the separate tap or winding has lower impedance so the bias supply will respond faster to B+ adjustments.

Andy Le Blanc · Post by **Andy Le Blanc** » Wed Dec 25, 2013 3:05 pm

thats a little gem right there

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