Jerry Lynds wrote:
Hello,


I need some help determining what value of zener diode is in the path
between the LMH1251 RGBout and the input of the LMH6739.

D1, D2, D3 in schematic below...

http://img333.imageshack.us/img333/6...scoder29mx.gif

or

http://www.national.com/ds/LM/LMH1251.pdf page 9 figure 2

I don't think these are zeners, but Schottkys.

The capacitive coupling is followed by 10k resistors to
ground, that would otherwise try to center the signal swing
at zero volts. But the diodes clamp the negative swing to
about -.3 volts, by charging the capacitors positively, so
that, as long as the signal cycle occurs much quicker than
the RC time constant, instead of being centered on ground,
it has a maximum negative excursion just below ground. So
the diodes are part of a level shifting scheme. I suspect
almost any small signal Schottky diode would work, as long
is it has a voltage rating well above 5 volts.