Forgot to mention, I put that diode and inductor inside my HP GPS Distribution amps retrofitting all of them, it fits quite well. HP uses a similar inductor (but smaller current capacity) to feed antenna power into the Antenna, so the effect of this is negligible. But caveat-emptor: this only protects the center conductor from voltage surges. One still needs to properly ground the antenna cable with a massive ground post to prevent the cable from carrying high voltages to the inside of the house. BTW: these voltages can and often are also be generated by antennae falling into High Voltage power lines. This happens more often than one would think in the US! Another interesting tidbit: in frost areas (Nordig countries, Canada/Alaska etc) the freezing ground turns into a very poor conductor, and any grounding post looses a lot of its current-carrying capacity by becoming high impedance. bye, Said In a message dated 2/29/2008 15:40:19 Pacific Standard Time, SAIDJACK writes:
Hi Tom, couple of problems with these gas discharge devices: they need a significant voltage to trip, and usually may only help when the hit is a vicinity hit, not a direct hit. For direct hits, the goal is to prevent human casualties, and fires. I don't think any sensitive RF receiver will survive a direct hit without significant change in performance, or failure. Well, the antenna and cable would likely be vaporized anyways. In my experience, putting a low-voltage TVS surge protector such as the Sision/Panjit 3.0SMCJ24A 3KW diode from RF center to ground (using a 22nH to 33nH high-power (2-3A) inductor to keep the RF away from the diode) helps protect receiver inputs against most proximity hits with minimal effect on the RF signal. This diode will quickly conduct above 24V surges, the Gas tubes need typically 100's of volts to start conducting. I used these in a Satellite receiver that was sold in large volumes across the US after we had a number of receivers returned from the states with active lightning with input failures. A 33nH inductor and 3KW TVS took care of the problem. The impedance of the 33nH inductor at 1.574GHz is high (>300 Ohms) so the transmission loss is << -0.023dB accorcding to AppCad. bye, Said In a message dated 2/29/2008 14:51:00 Pacific Standard Time, [EMAIL PROTECTED] writes: I'd be interested in reports on how well these work for GPS antennas, both in terms of lightning protection and in terms of attenuation, tempco, or phase delay. /tvb ____________________________________ Delicious ideas to please the pickiest eaters. _Watch the video on AOL Living._ (http://living.aol.com/video/how-to-please-your-picky-eater/rachel-campos-duffy/2050827?NCID=aolcmp00300000002598) **************Ideas to please picky eaters. Watch video on AOL Living. (http://living.aol.com/video/how-to-please-your-picky-eater/rachel-campos-duffy/ 2050827?NCID=aolcmp00300000002598) _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.