[Premium-Rx] Beacon Hunting

[Ben Dover]

Hello Jeff.

An NDB (nondirectional beacon) is an aviation navigational aid. The pilot's
ADF
(Automatic Direction Finder) receiver will point to it, and since the NDB is 
is usually on the airport grounds it gets him into (hopefully) visual range of
the runway.

Occasionally, NDBs are used to mark obstructions; I remember being rather 
surprised to find that an NDB used to be (maybe still is) attached to a
very tall
TV tower in the Dallas area, simply to mark it's location and warn aircraft
off
of a potential collision hazard. Information on the NDB in this case is
clearly
marked on the sectional navigation charts that pilots use.

They're in the bands of 194 - 420 and roughly 515 - 540 KHz. There used to
be some
in the 1600 - 1800 KHz band, mainly used in tropical areas because of the high
noise levels on LF. Pan American World Airways had a bunch of these strung
up and
down Central and South America. Also, in polar areas you'll encounter NDBs
in the
AM broadcast band because of ionospheric absorption factors; the former
USSR ran 
a whole lot of those, as does Greenland, Iceland, Norway and Sweden.

In the US, the vast majority of NDBs are licensed (by the FAA, not the FCC)
for
a power of 25 watts, and have a typical range of perhaps 10 miles radius.
Major
centers have higher powers; for example, ME (Midway Airport, Chicago IL) on
350
KHz is running 400 watts to a long wire antenna. It was intended to REALLY
stand
out to a range of 75 miles or so. On long haul routes over water the powers
of US
beacons can get to a couple of kilowatts; this is fairly common along the
Gulf 
coast and Carribean.

Canada has always depended on NDBs a lot more than the US, and those NDBs
usually
run higher powers, perhaps 4000 watts for big, main route NDBs along the
transcontinental airways.

In any case...   there's something about the challenge of getting solid
reception
of a 25 watt NDB from across the continent that's irresistable, especially
when
you consider that a typical NDB transmitting antenna is a simple, short Tee
strung
between two telephone poles...   not exactly the most efficient radiator
possible 
on long wave!

I hope that clarifies things about NDB addiction.


73's,

Tom, W9LBB



At 02:15 PM 3/31/2005 -0800, you wrote:
>OK guys, I've been following this thread and I'm curious...what are beacons,
>where are they, and why do you hunt them?
>
>- Jeff, WA6AHL