[BC] Part 15 radio station

[Craig Healy]

> >The NRC specifies that ALL antennas mounted outside be properly
> >grounded...  Thus, the NEC would clearly overrule the FCC part 15 rules
> >with regards to a SAFETY ground. The RF ground-now that is quite another
> >matter!
> ___________
>
> A wire from a Part 15 AM tx chassis to a buried ground rod/conductor may
be
> considered by the user to be a NEC-required safety ground for the 3-meter
> antenna, but in reality the antenna is not directly connected to that
> conductor.  Instead, such a "safety ground" becomes one arm of an
> off-center-fed dipole, whose lower tip is connected to r-f ground.
>
> An expanded-band Part 15 AM system mounted 20 feet above the earth and
> using a 20-foot ground conductor produces about 5 times the groundwave
> field intensity for the same applied power as when it is mounted with its
> base at earth level, with essentially no ground conductor length.  This
> gain is equivalent to using about 25 times the power with the system
> mounted at earth level.

How about if the thing is simply bolted to the top of a tower with no ground
wire at all?  If the guy wires are also conductively connected to the tower,
they become an elevated radial system.  It would be very hard to say that
the tower support is only a ground wire.

I can picture one of those things on top of a 2,000' tower.  Coverage, I'll
bet!

Craig Healy
Providence, RI