On Wed, Jun 25, 2014 at 4:42 PM, paul swed <[email protected]> wrote:
> I am currently using a 12AX7 as a ELF preamp and have for years. > A note in the coldest part of winter preheat the tube low filament voltage. > They tend to fracture. > It sits 200 ft from the house as far away in the woods as possible. > That said and back to the thread. At these frequencies tubes do work. The > 12AX7 can be found on vlf.it and numbers of tubes will work. They run 12 V > on the plate. They also stand up to nearby lightning very well. > So Diddier now you have no excuse. I can't wait to implement your design on > one of my stm boards. Not sure how to get this back on time-nuts topics > Regards > Try a 6DJ8 instead of the 12AX7. It has a higher GM and a LOT more bandwidth. What kind of risetime are we talking about for a lightning strike? And why not a loop antenna? That should provide plenty of signal but not destructive voltages. I know you are talking about measuring lightning strikes but if you get the impedance high enough, you can actually measure the earth's electric field. (It is about 200V/m if I recall properly.) Interestingly it is affected by the solar flux and solar wind. -- Brian Lloyd Lloyd Aviation 706 Flightline Drive Spring Branch, TX 78070 [email protected] +1.916.877.5067 _______________________________________________ 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.
