[R-390] OT: HP-410B Tubes

[Scott]

I brought a couple of HP-410B's back into service a few years ago. When 
doing so, an old HP friend who "engineered" in the HP Palo Alto factory in 
the old days recounted the 12AU7 burn-in and balance test rack in the "410" 
end of the factory.

HP apparently had problems  with 12AU7 section balance and drift too.

Scott, N6NXI