On 9/7/2011 8:54 AM, Jeff Liebermann wrote:
On 07 Sep 2011 13:27:08 GMT, wrote:

If you do not short the center conductor (on the DUT) to ground
immediately before connecting to the analyzer you risk discharging a
large "capacitor" directly into the instrument.

Good point except that none of the 3 analyzers that failed were
(allegedly) attached to equipment. They were attached to antennas.
Antennas normally do not have BFC's (big fat capacitors) attached, but
do build up static charges. With the humidity currently at 60% or
more, I don't think that's likely.


Actually, humidity doesn't affect the charging all that much. What
humidity affects is the leakage current across dirty insulators.
P-static is a nice example of static charging in rain at 100% humidity,
for instance.

It's true that dry dust or blowing snow are more notorious for charging,
but just the clear sky current could provide some charging.



Also, any antenna design, that
would fry an analyzer, might also fry a radio front end. It's
possible, but unlikely.


I don't know about that. A LNA with a FET front end might be an example
of a ESD sensitive thing, but for HF, where we're usually more concerned
about instantaneous dynamic range and strong signal handling, a more
robust front end is common. One of those +20dBm LO mixers, for
instance, is going to be quite robust.

I can think of a lot of antennas that won't be too hard on a radio front
end that would cook a delicate detector diode hooked directly up to the
antenna.




If I am at an antenna
farm I am grounding all my test gear prior to putting it into service.
There is a Ground lug on the 259B right next to the SO239. They
provide a Type N adaptor with a new meter, too, BTW.

I carry a neon lamp line tester in my tool box. It's useful for
checking AC power, but also for detecting high voltages on antenna
terminals. It's amazing what I find at broadcast sites.


There's a whole literature on making neon lamp blinkers with an antenna
and a ground.