[TowerTalk] Tuned feeders.

[Bill Coleman AA4LR]

On 10/6/97 11:27 AM, Tom Osborne at w7why@mail.coos.or.us wrote:

>Hi guys.  Thanks for all the replies to my questions about the tuned 
>feeders.  Now another one.  The antenna I put up is a 130 foot dipole fed 
>with twin lead.  It works great on the WARC bands and 10 meters.  I tried 
>to use it this weekend on 10 meters, but the noise from my computer is 
>awful!  The tuner is pretty close to the computer.

Is the tuner in a sheilded box?

>If I ran the twin 
>lead to the entry point of the shack, then used a couple of pieces of 
>coax (grounding the shield) for the run to the tuner, would that work to 
>keep the noise out of the computer?  I'd just go ahead and try it, but I 
>don't have any extra coax laying around. Thanks

It might help. But if the tuner isn't sheilded, probably not much.

You might consider what I do, with a very similar antenna. I run coax 
from the tuner to the outside of the house, then switch to ladder line 
using a balun. I use a 1:1 balun, but a 4:1 should work as well.

Make sure you use good quality solid-dielectric coax in this service. 
RG-8 or RG-213. Remember that the coax is in the path of a conjugate 
match and there may be signifcant capacitive or inductive reactances 
present along the length of it. The last thing you want is a voltage 
breakdown of the dielectric.

Be sure your balun is also setup to avoid voltage breakdowns. And keep 
the coax run as short as possible.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
Quote: "Not in a thousand years will man ever fly!"
            -- Wilbur Wright, 1901


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