[TenTec]Tuners and ladder line in the shack

Bob & Linda McGraw K4TAX RMcGraw@InfoAve.Net
Tue, 30 Jan 2001 16:30:07 -0800


What Steve wrote is absolutely correct.  Folks, get off the idea of
using 2 pieces of coax to run through the wall from the tuner to the
outside point on the balanced feed.  Your just kidding yourself.

73
Bob K4TAX

Steve Ellington wrote:
> 
> >
> > One suggestion was to install a 4:1 Balun just outside the house to transform
> > the open wire feeder to coax. Doesn't this defeat the purpose of using an open
> > wire feeder to begin with?
> >
> > How about using a PVC conduit to route the ladder line to the operating desk?
> 
> Yes it does seem to defeat the whole purpose of using open wire feeder.
> The assumption here is that since coax is "shielded" then we can run it
> through walls, over pipes etc. but think about it: If we connect a
> balanced line to coax then rest assured there is going to be plenty of RF
> on the outside of that so called shield. So what did we accomplish that we
> couldn't accomplish by just running some insulated, open wire through the
> wall? Well what we accompished was the introduction of a random, unknown
> and sometimes extream impedance to a transformer which will have an
> unknown effect on the random mess we fed it resulting in who knows what on
> the 50 ohm coax which could have considerable loss on 20m and lower.
> 
> In your situation, I would do my best to use balanced line all the way to
> the tuner and make sure it's well insulated. 450 ohm window line is fine
> and it only needs an inch or so clearance. Running it through PVC wouldn't
> help a bit if the pvc is against an electrical conduit. If you ran a 4"
> PVC pipe and somehow suspended the line down the center by using tension
> somehow then that would be great.
> 
> Steve Ellington N4LQ
> N4LQ@IGLOU.COM
> 
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