I have been a bit out of the circuit the last couple of days regarding
this thread. Yours seems a very thorough investigation.
Please excuse me if I revert to my MW BC experience. At a number of
installations the radials were tied together at a uniform distance from
the tower. There may or may not be a ground steak at that point. Then
the far ends of the radials are tied together again. The practice is
copper wire and strap and certainly not insulated from ground.
At one 2 tower daytime and 6 tower nighttime array (10KW on 940 KHz.)
the bases of the towers was actually physically raised a few feet above
the ground and then the radials went out from the base insulator at that
height above the ground and thence down to the usual earthed
arrangement. The consulting engineer thought that this stabilized the
impedance and phase parameters of the towers. I seem to remember that
these radials were bonded together by a strap at ground level.
This following episode was told to me by an old time BC engineer about
an early station located in the state of South Dakota.
It was not at all unusual for stations, studios, anyhow, to be located
on the top floor of some building. It was not so common for the
transmitter to be there as well. But in this case, that is where the
transmitter was indeed situated, perched proudly above the highest
prominence on the roof of this particular hotel.
The testing of the station went very well. It was in the middle of the
night.
But on the day of the official sign-on, and there were several
dignitaries there, it was impossible to keep the station on the air
because it was impossible to keep the antenna tower in tune.
It had been mounted on the top of the elevator (hoist) shaft! And as
the greeting crowd and other business started for the day the elevator
acted like a very large tuning slug!
Ahhhh! The best laid plans.
For my "D" beacon 0n 175 KHz., I have found signal strength improved as
more grounding is connected and I use power neutral, water system, and a
couple of 8 foot rods. There are so many soil types here in Iowa that
there is another factor to consider.
Doc.
_____________________________________________________________________________________
vernall wrote:
Rik Strobbe wrote:
>
> At 09:51 24/07/99 +1200, ZL2CA wrote:
> >Connecting the mains earth to the RF earth INCREASED THE RF RESISTANCE
> >OF THE ANTENNA.
>
SNIP...
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