[Elecraft] RE:balanced tuner

[David Cutter]

For long horizontal lines near to the ground (<3ft, 1m, say) I've read that 
some folks rotate the line between supports, supposedly to maintain balance; 
what do you think about that?

David
G3UNA


----- Original Message ----- 
From: "list1" <list1 at pituch.net>
To: "Elecraft Discussion List" <elecraft at mailman.qth.net>
Sent: Monday, August 18, 2008 4:29 PM
Subject: [Elecraft] RE:balanced tuner


> Hi David and all,
>
> I have done a lot of EZNEC dipole simulations and have come to the
> conclusion that the loss in 100 feet of coax off of resonance is about 12 
> dB
> per 100'.  Whether you use RG-8x or LMR400 doesn't make too much dfference
> concerning losses off of resonance where your SWR with 50 ohm transmission
> line can be greater than 200:1.
> <http://www.pituch.net/Steve%27s%20Page/Radio/Antenna4/Antenna4.htm>
> Because of this if I use 450 Ohm ladder line to a 1:1 baun, I try to keep
> the length of coax going into the house less than 15 feet. For your 50 
> feet
> of coax run you should never have a loss greater than about 1 S unit (6 
> dB).
>
> When I went to 100 percent ladder line including inside the residence, 
> when
> I built my balanced tuner, I used two 1/4-20 stainless steel bolts to feed
> the signal through the exterior wood wall. I have "U" solder lugs on the 
> two
> wires at the end of the 450 Ohm line, and I use two wing nuts to connect 
> the
> ladder line to the house connection.  When I am finished operating I go
> outside at spend 5 seconds loosening the wing nuts and the ladder line is 
> no
> longer connected to the residence.  If I wanted further protction, I guess 
> I
> could drive a ground rod 15 feet away from the residence and wing nut the
> end of the ladder line to it when I am not operating.
>
> I don't believe you can keep your antenna connected to your equipment and
> ever be completely protected from lightning strikes (and that includes
> coax).  The air gaps don't work.  For coax the gas surge traps may work to 
> a
> degree, but I would much rather disconnect the transmission line than 
> depend
> on one of these devices.
>
> If you want so-called protection for 450 Ohm line why not use 2 Alpha 
> Delta
> coax surge traps - one for each wire of the 450 Ohm line?
>
> The thing about keeping the 450 Ohm line away from metal is overdone a 
> bit.
> I find keeping it away from metal about 2 or 3 inches is fine.
>
> Regards,
> Steve, W2MY
>
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