[TowerTalk] 43' Vertical - Feed Point Tuner or Shack Tuner?

[Terry Conboy]

It would appear that the SWR curve that is still on the Array Solutions 
web site was measured with a misapplied 4:1 voltage balun (which puts 
half of the antenna RF voltage on the outside of the coax shield).  
http://www.arraysolutions.com/Products/zero_five.htm

This could probably explain how an SWR of under 2:1 is obtained in the 
160m band, where a 43 foot antenna alone has a modeled impedance of 
about 7.5 - j 570 ohms over a good ground system with a 5 ohm equivalent 
loss resistance.  This should give an SWR over 100:1 in either a 50 ohm 
or a 200 ohm system.

73, Terry N6RY

On 2009-02-01 8:09 AM, K4SAV wrote:
> Here is an article that should answer your question:
> http://www.vk1od.net/multibandunloadedvertical/index.htm
> Also notice the paragraphs about the balun used in some of these antennas.
>
> Here is a link to a long discussion on this balun, which eventually 
> determined that the manufacturer was including the wrong type balun for 
> use in this system.
> http://www.eham.net/forums/Elmers/201882
>
> Jerry, K4SAV
>
> Richard Thorne wrote:
>   
>> I have a vertical in my backyard that I currently feed at the base with 
>> an SG-239 200 watt tuner.  I want to increase my power from 100 watts to 
>> 400 watts.  In order to accomplish this I either need a tuner at the 
>> base like an SG-235 or CG-5000 both expensive.
>>
>> The other less expensive solution is a tuner in the shack.
>>
>> So how much loss will I have if I tune a 125' length of coax?  I know it 
>> works as I bypassed the base tuner and used my rigs tuner.  No problem 
>> tuning, I'm just curious how much loss I'll have compared to the tuner 
>> located at the base of the antenna.
>>
>> Rich - N5ZC
>> _______________________________________________
>>