Sidac vs TVS?

Dear all
Please help me to know what's the difference between an:
- Transient-voltage-suppression diode  (TVS)  and    Sidac ??? Can I use P6KE120ca (TVS) replacementMK1V125 = K1200 (Sidac) in this circuit. please see photo .Thank you so much.

Picture of Sidac vs TVS?
iceng2 years ago

The sidac ( first picture ) fires like an SCR at 125V and delivers the charge of the 1uF capacitor through the pulse XFMR to trip the gas tube

Also sidacs are much more subject to early firing due to dV/dT...

.

The P6KE suppression diode ( second picture ) is like a power zener and does not discharge the capacitor through the pulse XFMR....

.

NO you cannot substitute it for the Sidac.

BTW thanks for giving me a reason to warm up my tube Curve-Tracer,

Current is vertical and Voltage is horizontal.

See the ( third picture ) set up for a P6KE33 at 2ma Vert and 10V Hor.

photo(1).JPGphoto(3).JPGphoto(2).JPG
lam (author)  iceng2 years ago
Dear iceng..
Thank you very very much for your time
make the photo and helpful.
Best regards
lam