[TowerTalk] B.C. antenna

[Tom Rauch]

> Take a LW and stretch it out and loop the other end several turns around
> the radio in the same direction as the loop (try the other way also).  Add
> a series BC variable to the ground of the radio or back on it self.  Some
> combo of this will couple in some RF that you will notice.  Or better yet
> try this.

I think you are saying try winding in parallel with the internal loop 
and try winding at right angles, but I want to be sure. 

Reversing the winding direction (CCW vs CW) of a separate 
winding, with all things remaining equal, does not change the 
mutual coupling. If you don't have enough coupling, you need to 
change the location or axis direction of the winding, or number of 
turns.
 
>  Run the so called LW just to a ground and do the same thing.  The ground
> side of the 110 line works great.  Find the grounded wire first of a 2
> wire line with a neon lamp.   Use the 3rd in-between wire of a 3 wire
> line.  You will find out how good a ground connection is for a BC AM
> antenna when properly tuned with a 1000 uufd variable.  They try it on
> 160M then be prepared for another surprise.  Hook it to an oil tank for a
> great high surface area ground.  It works great on Xmit also.  K7GCO

I think using the leads in a power line, no matter how you check 
them, as a sole ground is very bad advice.  You are depending on 
the integrity of not only the internal house wiring but the grounding 
outside the house for your very life.

There are a number of cases where a single connection failure 
somewhere in wiring could result in full line voltage appearing on 
the antenna.

Not only that, the power lines are almost always a major source of 
noise and interference. Computers, light dimmers, and arcs and 
sparks on insulators and in motors all use the powerlines as an 
antenna. 

While there may be cases where a power line lead is quiet and 
doesn't hurt S/N ratio, I can't think of any case where it is safe as a 
ground. The safety ground is probably acceptable, if you are sure of 
the integrity of the grounding system at the service entrance...but 
even then I'd use multiple grounds or isolate the connection through 
an AC rated capacitor, like a .01 uF 250 VAC disk.

I think the safest approach, and one that would offer the least 
noise, is a separate ground for the antenna. Otherwise you'd better 
use an outlet with a GFI breaker, before connecting an antenna to 
any of the wires.


73, Tom W8JI
w8ji@contesting.com

--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com