[TowerTalk] Good vacation antenna

[Wes]

I'll confess some difficulty (probably my failing) in understanding your 
point(s).  To try and simplify the situation to something my pea brain may 
understand, let's use a toroid at either location.  Now tell me what the 
difference is.

Wes  N7WS



On 7/3/2025 3:39 PM, David Gilbert wrote:
>
>
> Because whatever current is left after the loss in the tuner still makes it to 
> the antenna but doesn't have a major portion of it compressed inside the coil 
> where it matches and also suffers loss but doesn't radiate.  Radiated RF is a 
> function of BOTH current and length.  If it was otherwise we'd all be using 
> parallel tuned circuits with large coils on 40m instead of aluminum tubes and 
> wires.
>
> Dave   AB7E
>
>
>
>
>
> On 7/3/2025 2:11 PM, Wes Stewart via TowerTalk wrote:
>>    So you move the loading coil from the base of the antenna to inside the 
>> tuner in the radio (with some coax in between).  How does that affect the 
>> radiation efficiency/?
>> On Thursday, July 3, 2025 at 01:57:33 PM MST, Jim Brown 
>> <jim at audiosystemsgroup.com> wrote:
>>> https://www.dxengineering.com/parts/cha-ss25
>> That looks like a great solution, Dave! I strongly suggest against a
>> loading coil for 40M, using a tuner built into the radio instead, with
>> or without some top loading. Loss in short lengths of decent-size coax
>> on 40M is pretty low, even with significant mismatch. An excellent study
>> in QEX about ten years ago showed that inductive loading at the base
>> greatly reduces the radiation efficiency, because it's at the current
>> maxima! The study included the construction of multiple configurations
>> of loading, and very rigorous measurements.
>>
>> 73, Jim K9YC
>>