[BC] AM Ground Systems & Ground Conductivity

[Jerry Mathis]

Scott--would highly recommend you do what we did in Waynesboro, TN years
ago. Put a decent ground system in, then run field strength measurements.
You'll need a consultant to do this, at least the paperwork and study, you
can do the legwork if you want, but beware, it's a LOT of legwork! The
consultant can then tell you if you can make improvements. We were able to
go from a 1 KW daytimer on 1480 to 1400 fulltime, then later to, I believe
it was 920 KHz. Like you, the M3 map showed a conductivity of 4, our
consultant found it was about .5. You might not be able to go to a lower
frequency, but you might get more power on 1560.

Yes, this'll cost money, but it's about the only way to find out if you can
improve yourself. Doing your own legwork (taking the FS measurements) will
knock a lot off your bill with the consultant.

JM


On 12/21/06, Thomas G. Osenkowsky <tosenkowsky at prodigy.net> wrote:
>
> Do not confuse ground conductivity with ground
> system efficiency. They are very different. In CT
> and New England, you are lucky to get a 0.5
> conductivity! M3 is much more optimistic and
> many stations have been granted power increases
> based on measured data, especially when probe
> measurements are conducted in the middle of
> summer.
>
> Some stations have used barbed wire for radials.
> I don't know about a waiver for shorter radials.
> I would inquire if there is a precedent for this,
> or perhaps an exhibit demonstrating compliance
> with minimum efficiency Rules may help. Being
> on the high end of the band is a handicap. Your
> tower is 86 degrees which is good. An efficient
> ground system is critical where ground conductivity
> is low and the frequency is high. As far as the
> base impedance is concerned, it is important to
> know if it was measured when the antenna had
> a full or compromised ground system.
>
> Tom Osenkowsky, CPBE
>
>