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 **************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 -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
