Two zener diode back to back??

I found this as a zener limiter. I am curious if it has any different for being connected + to + or negative to negative. sorry for sound like a electronic novice.

Thanks for your reply. Actually, the 100V AC is from the emitter output of a transmitter. The circuit is a small AC signal drive the transistors in order to amplify to a larger AC signal. That Zener limiter is connect to the ouput of that amplified AC signal and ground.

You didn't say where this 100V AC comes from. The circuit draws a current from this source. Depending on the impedance of the source, it may limit the swing a bit.