Topband: PolyPhaser Model IS-50UX-C0

[Roger D Johnson]

Harold Smith wrote:
> 
> 
> 
>> Harold Smith wrote:
>>
>>
>>> I measured the breakdown voltage and found it to be 350 volts which 
>>> is 2450 watts at 50 ohms. That is
>>> why they rate it a a maximun of 2KW.
>>>
>>
>> Not quite! The spark gap will arc at the peak voltage on the line. 350
>> volts peak is only 1225 watts on a 50 Ohm line and that is with a 1 to 1
>> SWR.
>>
>> There seems to be some confusion between draining static charges and
>> lightning protection. About the only thing that will give you lightning
>> protection is a hefty spark gap at the base of the antenna.
>>
>> I just had a thought about RADAR technology. When the spark gap at the
>> antenna fires, it will produce a low impedance at that point. This means
>> that 1/4 wave down the line will be a high impedance point. Perhaps this
>> would be a good point to install a Polyphaser type of suppressor.
>>
>> 73, Roger
> 
> The voltage from a lightning strike is mostly DC not AC. If it would 
> breakdown at 1225 watts, then why does
> PolyPhaser rate this model at 2000 watts from 1.5 to 50 mHz. Also what 
> is a quarter-wave at the lightning frenquency?

I went back and dug out my Polyphaser manual. The spectrum I remembered
was for EMP not lightning! Lightning appears to have a very wide
bandwidth with a broad peak near 5kHz (from what I can find on the web).

I think that a resonant antenna would show a definite peak at it's
resonant frequency when excited by a lightning strike. If that's the
case, then I think my idea of having the Polyphaser device 1/4 down
the line has some merit.

73, Roger



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