Feedline radiation is the same way that the TAC antenna gets an SWR of
1.0 on 40 meters from an antenna that has a feedpoint impedance close to
5 ohms.
It appears your Zero Five conclusions are correct. The SWR data on the
website appears to be taken using either the 200-T-1220 balun ot the
"AS-200-tuner" balun. They are now recommending the ZF-MB-5K UN-UN.
Assuming it is really an UN-UN it wouldn't produce the curves shown. I
guess they conveniently forgot about that. Maybe they don't know.
It seems that in the beginning Zero Five recommended the ZF-MB-5K for
use with this antenna. Sometime after that, someone somewhere screwed
up and started recommending the "AS-200-tuner" balun, also they must
have recommended the 200-T-1220 too since some of these antennas have
that one too. Array Solutions now seems to have now done a flip-flop
and fixed the web page, except for the data.
I have visions of someone running SWR curves with various baluns and
picking the "best one".
Jerry, K4SAV
Terry Conboy wrote:
> 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
>>> _______________________________________________
>>>
>>>
>
>
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