[TowerTalk] Was "43ft Vertical Feeding

[jbigham2]

I found this out trying to use a six foot stainless CB whip with auto tuner 
in bed of truck under it.  No mount insulator on the market would withstand 
the voltage generated by a 100 watt output radio tuned for 80 or 40 meters 
for any length of time until I found delrin machined standoff made by a 
fellow who sent me one and the problem is now fixed.  The voltage across the 
feed point of a short antenna can be considerable as I discovered.
Gene Bigham KB0GU

----- Original Message ----- 
From: "jimlux" <jimlux at earthlink.net>
To: "David Jordan" <wa3gin at comcast.net>
Cc: <towertalk at contesting.com>; "'Samir Popaja'" <7s7v at adamomail.se>; 
"'Richards'" <jruing at ameritech.net>
Sent: Tuesday, November 25, 2008 10:45 PM
Subject: Re: [TowerTalk] Was "43ft Vertical Feeding


> David Jordan wrote:
>> The high voltage appears at the tip of the vertical, where the corona 
>> ball
>> goes. I believe the feedpoint is the high current portion of the antenna
>> where most of the radiation starts...
>>
> only on a 1/4 wave antenna. Short antennas or Antennas close to a
> multiple of a half wavelength at the operating frequency can have very
> high voltages at the feedpoint.
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