[Elecraft] NOT the feedline

Bob McGraw K4TAX rmcgraw at blomand.net
Tue Jun 2 11:50:48 EDT 2020


It is correct that there is no such thing as a breakdown voltage, as 
stated earlier. This becomes obvious since the units are given as V/m, 
which is represents Volts per meter, or Electric Field strength.

Also, unless one is measuring the field in between two plane parallel 
metallic plates, the Electric Field will, in general, not be uniform, 
I.e., the field strength (the amount of "pull" on an electron), will 
vary with position. This shape does matter, and sharply pointed emitters 
can cause breakdown at values considerably less than the maximum 
measured in a uniform field.

The Volts/meter relationship is also pressure-dependent, and this 
relationship goes nonlinear at low pressures (not enough charge 
carriers) following Paschen's law 
<https://en.wikipedia.org/wiki/Paschen%27s_law>. It also varies with 
humidity and other contaminants, which usually increase arcing.

73

Bob, K4TAX


On 6/2/2020 8:54 AM, john at kk9a.com wrote:
>
> The RMS voltage for 1000 watts into a perfect load is <250 volts. I 
> suspect that Tony's 4,000 voltage limit is closer to what a quality 
> PL-259 can actually handle. If the PL-259 is arcing, there is 
> something very wrong with either the connector, the weatherproofing or 
> the antenna.
>
> John KK9A
>
>
>
>


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