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Hi Dave
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The charge only accumulates if it is connected to an antenna that is not a DC short.? ?i.e.? long wire, gama matched Yagi, 1/4 wave vertical etc. Not a problem with a folded Dipole, loop, or the antenna has most balun designs. We use to connect an NE-2 neon lamp across the coax connector to a long wire antenna.? ? ? ?Takes about 80 volts to light up an NE-2.? ? ? ? ? ? ? ?Brisk breeze when the humidity was low and that neon light would flash every few seconds.? ?? This is why most preamps have a 10K resistor across their inputs to bleed off that change. OK, in the shack, but for outside antennas I would not connect my VNA's to an antenna that is not a DC short. Kent WA5VJB? ?Antenna Editor CQ Magazine. On Thursday, February 4, 2021, 02:56:03 PM CST, David Eckhardt <davearea51a@...> wrote:
A coaxial cable is a long cylindrical capacitor.? Being by design low loss, it can accumulate and store a charge for quite some time.? When connecting any longer piece of coaxial cable or other low-loss transmission line, I always make it a habit before connecting it to anything expensive or valued by pressing my finger across the end to discharge any accumulated charge. Sometimes, there is nothing, but the first time you get 'bit', you will become a believer.? Transmission charge is highly likely to accumulate during a thunder storm, wind-blown dust orsand, and even snow fall. Dave - W?LEV On Thu, Feb 4, 2021 at 1:27 PM schweppe <schweppe@...> wrote: When looking at the front end of the nanovna you see a 10?F capacitor in-- *Dave - W?LEV* *Just Let Darwin Work* |
