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

[Chuck Harris]

As I recall, the Boonton 535A isn't specially made at all,
but rather a selected 2A6 triode/twin diode.  The tube is
selected for having an especially clean vacuum, and being
capable of running with a really high grid leak resistor (100M).

-Chuck Harris

Bill Hawkins wrote:
> A couple of other things about dealing with lightning:
>
> There is a cone of protection starting at the highest grounded point
> around for about 100 feet.
> These were developed to protect explosives bunkers from direct hits.
> The angle of the cone (between a vertical line to the tip and the edge
> of the cone) is 30 to 45 degrees.
> Exceptions have been reported, of course. That should save you from most
> direct hits.
>
> Then you have to deal with the electric field that builds up from
> passing charged clouds.
> Some kind of high-value resistor in parallel with a small glass sealed
> spark gap from antenna to ground would help.
> It doesn't have to deal with a direct hit, just keep the grid from
> arcing in the tube.
> Some of the sealed spark gaps also contain inert gas. You don't want a
> triggered spark gap, just a surge suppressor.
>
> Old radios with octal sockets had tubes in the RF and IF amplifiers with
> grid caps, like the 6K7.
> Should be a lot more available than the Boonton 535-A.
>
> Bill Hawkins
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>