[TowerTalk] 4 SQ WX0B box

[Jan Erik Holm]

Well, not quite I think. I think it´s one LC network
for CW part of band and one for SSB part.
W7EL  network doesn´t have enough bandwith to cover
3500-3900 kHz, you need to use two LC networks or
just use one and retune it.
Still no explanation what the "new Lahlum" metod is.
Seems to be a modification to Lewallen but what is
Lahlum? Is it a person or what is it???
Looks like you can use two phasing setups, 0 -90 -180
like Lewallen and  also 0 -124 -224, maybe the later
deal is the "new Lahlum"
I would have tought that WA3FET was the father of the
second phasing setup, think K3LR was involved in it
too.
Time will tell I guess!

73 Jim SM2EKM
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Jim Lux wrote:
> At 05:28 PM 11/18/2004 +0100, Jan Erik Holm wrote:
> 
>> Just checked the WX0B website and his 4 SQ box.
>> As far as I remembered it used to use the Lewallen
>> current forcing method however now he is talking
>> about "the new Lahlum" method. Anyone know what
>> that is? Sure looks like current forcing to me.
>> Or do I have to wait until 2005 to read it in ON4UN´s
>> book.
>>
>> 73 Jim SM2EKM
> 
> Looking at the photo, I'd imagine it's a set of multiple LC networks, 
> rather than a single network as used in the W7EL. This lets you do a bit 
> better job synthesizing the phases, and potentially could remove the 
> requirement for 1/4 wavelength lines, which creates a bit of a 
> installation problem.  For instance,you could use 1/2 wavelength cables.
> 
> 
> Unfortunately, the manual is a dead link(404), so I can't comment further.
> 
> This is a good compromise solution when you want to have your switching 
> centralized, and with a reasonably symmetric array.  You do have 
> potential loss from circulating currents in the feedlines. The reactive 
> component to cancel the feedpoint reactive component is back at the box, 
> so the reactive power is carried in the feedline.  In an ideal system, 
> you'd have the reactance at the antenna, so that the feedline is at 50 
> ohms, and all the box needs to do is generate the right phases.  Of 
> course, the matching network at the antenna would then need to have 
> multiple values, since the feedpoint impedance changes with the array 
> steering direction.  And, it would be quite "challenging" to tune up 
> (broadcast antenna engineers earn their pennies doing this).
> 
> It would also make the total system cost higher.
> 
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