🚀 go-pugleaf

In article <6wadah7hpf.fsf@saul.cis.upenn.edu>, sam@saul.cis.upenn.edu 
mentioned...
> Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> writes:
> 
> > I had a cheap scanner that used semi's on the input.  The first 
> > lightning bolt many miles away zapped them.  Got out the soldering 
> > iron and replaced.  Same thing again, later.  Pi$$ poor design.
> > 
> > Don't waste your time.  Use an inductor that has nearly zero ohms DC 
> > resistance, or your front end will suffer the same fate.
> 
> And the inductor is used how?  In series it will block the RF.  In parallel,
> it will still look like a high impedance for the fast rise time spike of
> a zap.

Well, the scanner has three front ends, UHF, and hi and low VHF.  The 
UHF and hi VHF have inductors, and use FETs, and they aren't damaged 
by lightning.  But they are coupled to the antenna coax with small 5 
or 10 pF caps, so their inductors don't protect the lo VHF.  The lo 
VHF uses no inductor and a BJT, MPS-H10, and it burned out with every 
lightning strike.  That seems to me to indicate that the coils conduct 
most of the fault current to ground.  I suppose the coils do let some 
of the high freqs thru, but not enough to do damage.

Hams do the same thing with their tried and true homebrew equipment.  
They put some DC path to ground in the incoming coax.  This also 
conducts to ground AC current picked up by the antenna.


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