Re: [IRCA] SHORT VERTICALS

["Mark Durenberger" <Mark4@xxxxxxxxxxxxxxx>]

That was my guess as well, Nick...altho the array doesn't seem to be 
freq-sensitive (i.e. a 4:1 and a 16:1 deliver the same relative signals at 
both ends of the band).

Otherwise...I like your 'antenna-tuner' idea :-))



Regards,

Mark Durenberger


-----Original Message----- 
From: Nick Hall-Patch
Sent: Saturday, March 01, 2014 2:07 PM
To: Mailing list for the International Radio Club of America
Subject: Re: [IRCA] SHORT VERTICALS

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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