Jerry,
I think you are correct. these are schottkys. these 100uf caps can put quite
a negative punch with out limiting the charge current. I would use no less
than the IN5817 no 18 nor 19.
Ray


"John Popelish" wrote in message
. ..
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.