Re: Black burst

I think that it's sad that you rely on an antique piece of gear like the Tektronix 1470. This product hasn't been made in years, and a cheap box like the Horita BG-50 for $209 at B+H Photo resolves all of your problems.
I can assure you that black works just fine into an AJA I/O Reference Input, and so I would bet money that there is a problem with the black output of your 1470. Of course, for Tektronix to even evaluate the problem for repair would cost more than simply replacing it with a small new black generator like a Horita, or similar brand.

bob Zelin