HV protection for receiver input?

[Active8]

In article <if7hjvgt4aaguuoghj5n088m707uls7m52@4ax.com>,
void@nowhere.com says...

On Sun, 10 Aug 2003 16:22:48 +0100, Paul Burridge
redscar@waitrose.notformail.com> wrote:

On 10 Aug 2003 09:41:48 -0400, Sam Goldwasser <sam@saul.cis.upenn.edu
wrote:

And the inductor is used how? In series it will block the RF. In parallel,
it will still look like a high impedance for the fast rise time spike of
a zap.

Good point, Sam. So what's the definitive answer?

1.5KE30CA (1500W 30V bidirectional Tranzorb).
Couple of bucks each.
General Semiconductor.

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

 

[Vermin]

On Sun, 17 Aug 2003 01:20:50 GMT, Active8
<mcolasono@earthlink.net.invalid> wrote:

In article <if7hjvgt4aaguuoghj5n088m707uls7m52@4ax.com>,
void@nowhere.com says...
On Sun, 10 Aug 2003 16:22:48 +0100, Paul Burridge
redscar@waitrose.notformail.com> wrote:

On 10 Aug 2003 09:41:48 -0400, Sam Goldwasser <sam@saul.cis.upenn.edu
wrote:

And the inductor is used how? In series it will block the RF. In parallel,
it will still look like a high impedance for the fast rise time spike of
a zap.

Good point, Sam. So what's the definitive answer?

1.5KE30CA (1500W 30V bidirectional Tranzorb).
Couple of bucks each.
General Semiconductor.

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:

http://www.search.epcos.com/pls/prins/para_search.init?M_SPRACHID=2&M_PRFA=6&M_PGRP=PG_SA_2E

 

[Active8]

In article <7an3kvkmp2sfteo1om0nus0nkiepq1mm2g@4ax.com>,
void@nowhere.com says...

On Sun, 17 Aug 2003 01:20:50 GMT, Active8
mcolasono@earthlink.net.invalid> wrote:

In article <if7hjvgt4aaguuoghj5n088m707uls7m52@4ax.com>,
void@nowhere.com says...
On Sun, 10 Aug 2003 16:22:48 +0100, Paul Burridge
redscar@waitrose.notformail.com> wrote:

On 10 Aug 2003 09:41:48 -0400, Sam Goldwasser <sam@saul.cis.upenn.edu
wrote:

And the inductor is used how? In series it will block the RF. In parallel,
it will still look like a high impedance for the fast rise time spike of
a zap.

Good point, Sam. So what's the definitive answer?

1.5KE30CA (1500W 30V bidirectional Tranzorb).
Couple of bucks each.
General Semiconductor.

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.

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

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:

http://www.search.epcos.com/pls/prins/para_search.init?M_SPRACHID=2&M_PRFA=6&M_PGRP=PG_SA_2E

 

[Michael A. Terrell]

Active8 wrote:

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.

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.
--


Michael A. Terrell
Central Florida

 

[Active8]

In article <3F42C2CE.8BC33F00@earthlink.net>, mike.terrell@earthlink.net
says...

Active8 wrote:

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.

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