[Lowfer] MP 137.780 ON

[John Andrews]

Paul,

> A broadcast engineer told me that he had a rule of thumb that he applied
> that said,  All other things being equal a 5 Kw AM braodcast station on
540
> Khz would be as well recieved as a 50 KW station at 1600 Khz.

That's true, and probably a bit conservative. The comment applies only to
surface wave coverage, as you point out, and not to skywave.

Remember that you're talking about a 3:1 frequency difference in the AM
broadcast band, though. The ratio between 136 and 185 kHz is only 1.36:1.  A
1/4 wave tower at 540 kHz is 455 feet tall, as opposed to 154 feet at 1600
kHz. Think similarly for the radius of the ground system. In actuality, many
"bottom of the band" installations don't have "full-size" ground systems due
to acreage limitations, and their towers may be shorter than 1/4 wave. On
the other hand, towers in the 1/2 wave region are more common at the top end
of the band, and can offer a few dB of gain over the 1/4 wave stick.

Just as an aside, we U.S./Canada guys have to remember is that the bulk of
the 136 kHz activity within EU has been during the daytime. I believe that
the same thing will happen here when the band is authorized. With larger
antennas and more power, we will be able to take advantage of the quieter
daytime hours. And since it will be ham radio, rather than beaconning, the
emphasis will shift toward 2-way contacts. Those are tough to do when both
parties are asleep!

JA