>
>
>Richard wrote:
>
>>
>> ? I use a Hertz antenna (end-fed multi half-wave; high feed-Z). Equal
>> currents flow into the antenna and the antenna tuner ground. The lead to
>> the ground system is 5' of two-inch wide copper strap (c. 200nH of
>> inductance). Thus, there is an RF voltage drop across the tuner ground
>> lead. If the tuner ground is connected to the radio ground, the radio
>> becomes hot with RF. I installed a coaxial choke balun to prevent RF
>> from going back to the radio.
>
>If you got an 18 kA lightning strike the voltage on the ground at your tuner
>would rise to around 18 kV due to the impedance of the 5 foot ground lead.
>That is assuming you had a perfect ground at the other end of the strap.
>
? 18kV is a semi-reasonable assumption,Gary . However, an 18kVpulse of
c.100kHz RF on the tuner case should not be a problem since the antenna
tuner is isolated from the amplifier with a 30uH, air-core coaxial
choke-unun. Also. the Hertz antenna has a 300k-ohm shunt resistor to
ground to bleed off static-charge build-up during thunderstorms.
cheers
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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