[TowerTalk] Hustler 6BTV vs Steppir Big IR Vertical on 80m

Ian White GM3SEK gm3sek at ifwtech.co.uk
Tue Nov 27 02:12:08 EST 2007


David Gilbert wrote:
>
>Ian White GM3SEK wrote:
>> With one more capacitor, it probably wouldn't be difficult to make 
>>the same network match on 40m as well, without switching. As a 
>>starting-point, try doubling all the L and C values in this 40/20m 
>>design:
>>
>> http://www.arrl.org/qst/2005/09/richardson.pdf
>>
>>
>
>That's a very cool idea, but I think he'd need a 65 foot vertical or so 
>to make it work with double those values.  The author himself suggests 
>that it's pretty hard to come up with values that work at all if the 
>antenna isn't on the long side for the lowest band, but I guess it 
>might be feasible to accomplish that with top loading wires.
>
I was assuming he might follow your suggestion to do that.

On 80m it would be a top-loaded T, to be fed at low impedance against a 
good ground. On 40m it would be what G3VA describes as an "inverted 
ground-plane" with its current point and two radials at 32ft, and 
high-impedance feed (though probably only several hundred ohms).

All three elements of the two-band matching network would need to be 
adjusted, so the doubled values from the 40/20m reference would be a 
good place to start from.


-- 

73 from Ian GM3SEK


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