Re: [IRCA] SHORT VERTICALS

[Nick Hall-Patch <nhp@xxxxxxxx>]

What is the inductance of the 200 ohm winding Mark?

My guess is that there's nothing a short vertical (which has a 
capacitive impedance) likes better than a little matching inductance; 
it's like a loading coil.   You might find that your improved 
sensitivity actually has a bit of a peak at a certain range of 
frequencies, perhaps damped by your receiver's 50 ohm 
impedance.  Maybe see how well some of the higher ratio matching 
transformers do at LW beacon frequencies in comparison?

Next step, built a tapped matching transformer, and use your 
transformer as an antenna tuner perhaps?

best wishes,

Nick


At 14:27 01-03-14, you wrote:
> I'm wrapping a 2,000-mile road trip and have occasionally stopped, 
> to stick up my 30-foot modified Dallas Lankford vertical.  And 
> something's been bothering me.
>
> Lankford's heritage 'short vertical' proposes a 4:1 base 
> match.  I've played with this ratio, from 2- to 16- : 1 and, indeed, 
> 4:1 seems best.  That would suggest about a 200-ohm antenna.
>
> But why?  30 feet at MW = about 200 ohms?  Doesn't seem right...
>
> Scratchin' my pate and anticipating wisdom from the list...
>
>
> Mark Durenberger
> On the Road
>
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