[Elecraft] RE:balanced tuner

[Brian Alsop]

Steve,

With all due respect, the problem isn't with the coax, it is with the 
antenna which is designed poorly for the frequencies of operation.   
Even traps in a decent multiband antenna design, fed with coax, wouldn't 
have a 6db loss of the ladder line you're claiming is OK..

73 de Brian/K3KO

list1 wrote:

>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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