Topband: Mag loop 400W if possible.

[Mike Waters]

On Sun, Nov 15, 2015 at 12:44 PM, jh-mty at sbcglobal.net <jh-mty at sbcglobal.net
> wrote:

> Use the largest, heaviest hardline you can find.


if you use hardline at all, it ought be be VERY BIG hardline! If the
largest you can find is (for example) 7/8", that's simply not big enough,
unless you are willing to put up with the reduced efficiency or make the
loop much larger.

What is needed for an efficient STL (small in terms of wavelength) is big
copper pipe. And if we use aluminum it needs to be even bigger than copper.
The entire STL --the loop itself, the tuning capacitor, and the connections
between them MUST have extremely low ohmic resistance vs. the radiation
resistance.

That almost always means large, expensive vacuum variables with wide copper
strap connecting it to the loop. Braided copper is out of the question, it
will heat due the enormous currents flowing in the loop.

Such an efficient STL also has extremely narrow bandwidth. Think that over
carefully, especially if you plan on using SSB.

 Also, rethink your resources.  I ran Top Band from a 2nd story apartment
> with a full-sized inverted L hidden in a tree, with radials running down
> the sides of the bldg., and worked 93 countries with 100-600W.
>

Bingo! An inverted-L is really the way to go.

73, Mike
www.w0btu.com