[TowerTalk] 1/4 wave vertical question

[David J. Sourdis - HK1A]

Tell me if I am wrong: The trap should be for 30m band, 10,1 MHz, not for 7MHzFrom the bottom of the vertical to the bottom of the 30m trap is around 1/4WL at 10.1 Mhz. NOT AT 7 MHz.At 7 MHz the RF is not trapped and uses the whole lenght of the antenna.


73

David  
HK1A
EC5KXA
ex-HK1KXA




> From: youngron at verizon.net
> To: towertalk at contesting.com
> Date: Sun, 18 Apr 2010 21:33:15 -0400
> Subject: Re: [TowerTalk] 1/4 wave vertical question
> 
> >From the bottom of the vertical to the bottom of the 40 meter trap will be 
> about 32 feet depending on the diameter of the vertical. The larger the 
> diameter of the vertical the shorter for a given frequency. The length above 
> the trap to resonate on 30 Meters will depend on the inductance of the trap. 
> I don't know what you are using but usually the 30 meter length would be 
> measured from the top of the 40 meter trap.  Put it up, run SWR curves for 
> both bands and adjust length to resonate on each band. 73, Ron W8RJL
> 
> 
> ----- Original Message ----- 
> From: "Dan Schaaf" <dan-schaaf at att.net>
> To: "Tower and HF antenna construction topics." <towertalk at contesting.com>
> Sent: Sunday, April 18, 2010 9:27 AM
> Subject: [TowerTalk] 1/4 wave vertical question
> 
> 
> >I am building a 1/4 wave vertical for 30 and 40 meters with a coax trap.
> > In order to do the initial measurements, can anyone tell me if the 30 
> > meter length includes the trap or if the 30 meter length stops at the 
> > bottom of the trap or in the center of the trap?
> >
> > Dan Schaaf
> > K3ZXL
> > "In the Beginning there was Spark Gap"
> > www.k3zxl.com
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