[time-nuts] Loran, GPS, Lightning, Timing

[Brian Lloyd]

On Wed, Jun 25, 2014 at 4:42 PM, paul swed <paulswedb at gmail.com> 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
brian at lloyd.com
+1.916.877.5067