Topband: Cone of Silence

[Tom Rauch]

> lengths in case there is such a beast. My impression is that when we
adjust
> the exact length of the beverage the most predominate effect is to adjust
> the phase of the signals being picked up by the vertical feeds so that
they
> differ by 180 degrees.(in some direction)

I'm not sure how important the ends are anyway. The amount of signal they
contribute is very tiny, and the whole Beverage responds to vertical signals
anyway.

 I do have one suggestion......

I  sweep the Beverage feedpoint over the desired operating range with an
antenna analyzer. I have the antenna somewhat misterminated (usually a
thousand ohms or so), and use the peaks and nulls of impedance to determine
the electrical length. The frequency difference between nulls is the
frequency where the antenna is 1/2 wl long! You can measure the true
electrical length that way using the 492/F=feet formula. If you saw an
impedance dip at 1.8 and another at 2.4, the antenna's electrical length
would be 2.4-1.8=.6 for 492/.6 or 820 feet.

I added the same method in the MFJ antenna analyzer firmware. They read it
out directly in the "distance to fault" mode.

If you like the cone of silence lengths (like John I don't find them
especially useful) then you can get it exact. This method is great for
finding the actual electrical length.

73 Tom