On Thu, 11 Sep 2008, Paul P wrote:

Looking for the specs for the 4H4-C ballast tube used in a National NC300.
I know about the 6X6 or whatever sub. I want to see why there is a 4.3 ohm
2watt resistor across said ballast tube socket. It is not reflected in the
schematic from BAMA. There is a 2.2 ohm in the schematic.

I can't give any date, but I have a vague memory of seeing an article
that described a solid-state replacement for that ballast tube. But
it's vague enough that it may be a false memory. Usually I can remember
where I would have seen such things, and I can't this time.

I just did a websearch, and nothing turns up. But, apparently that 2.2ohm
resistor was a factory mod or upgrade. Nothing on the 4.3ohm resistor
after a quick glance.

Michael VE2BVW