HV protection for receiver input?

Aug 06, 2003 24 Replies

thanks. i've been thinking tranzorbs while reading all this and didn't know who made 'em.

but those stun guns generate about 20kV. is the 30V spec above the voltage they turn on at?

br, mike

No.

That's the point.

The transorb will clamp the 20KV to about 30V (actual clamp voltage depends upon the pulse rise time) protecting your circuit.

They have very low capacitance (10 to 15pF) and so should not affect your RF.

Another option is a GDT (gas discharge tube), even lower capacitance (only a couple of pF) and can be purchased in as low as 90V DC clamping voltages.

See:

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sorry, I meant "the above 30V spec", not the "30V spec above" :-) i should have just left the "a" word out, but after a few days, it appears my grammatical error elicited a response.

hey. those GDTs are used to protect CATV amp ins/outs. those amps aren't cheap, so there must be something there. lower cost (?) and lower capacitance.

mike

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The CATV systems I worked on required the gas discharge tubes to be replaced as preventative maintenance, due to the tubes degrading slightly with each activation.

hi cable dog:

i can see that happening. i just built and activated the systems. line gear maint was for in house. design, new/rebuild, retro, some sweep, make-ready... i did it.

brs, mike

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