More on 500 kHz

[Andre Kesteloot]

>ARRL GRANTED EXPERIMENTAL LICENSE FOR 500 KHZ RESEARCH BY RADIO AMATEURS

The FCC's Office of Engineering and Technology on September 13 granted Part
5 experimental license WD2XSH to the ARRL on behalf of a group of radio
amateurs interested in investigating spectrum in the vicinity of 500 kHz.
The two-year authorization permits experimentation and research between 505
and 510 kHz (600 meters) using narrowband modes at power levels of up to 20
W effective radiated power (ERP). ARRL Member Fritz Raab, W1FR, of Vermont,
will serve as experimental project manager for "The 500 KC Experimental
Group for Amateur Radio" <http://www.500kc.com/> 

"I'm kind of excited to see how we can apply modern technology to a 'classic
part' of the radio spectrum," Raab told ARRL this week. He pointed out that
500 kHz - the traditional maritime emergency frequency - is roughly
geometrically halfway between the 136 kHz experimental band and the 160
meter amateur allocation. 

"In contrast to 160 meters, 500 kHz is low enough to offer good groundwave
propagation, but in contrast to 137 kHz it is high enough to allow us to
engage in real communication with realistic equipment." Raab eventually
would like to see at least a secondary 600-meter amateur allocation from 495
to 510 kHz.

"Besides the opportunities for experimenting at low frequencies, that
frequency is well suited to regional groundwave communication," Raab said.
He envisions eventual use of the spectrum to provide Amateur Radio emergency
communication via groundwave, without having to deal with the vagaries of
the ionosphere or causing interference to other services.

For about a century, the 500 kHz region was an important band for maritime
communication, emergency and otherwise. The band is occasionally used by
"heritage" commercial maritime stations, such as the Maritime Radio
Historical Society's KPH on the West Coast, on special occasions. 500 kHz
remains designated as an official maritime emergency CW frequency, although
the vast majority of maritime users have shifted to satellite-based systems.

In addition to experimentation and regional emergency work, Raab says he
believes that the 505-510 kHz spectrum could serve as "an historic band"
that could support various commemorative special event-type operations.
Proposals are under consideration in the UK and Ireland to establish an
experimental Amateur Radio allocation in the vicinity of 500 kHz.

The WD2XSH project calls for operation from 21 discrete fixed sites spread
throughout the US. Participants all are electrical professionals, many with
maritime radio backgrounds, Raab said, adding that operation already has
begun. The group eventually will be seeking reports from non-participants,
he said.

Raab says the gear participants will use represents "every kind of antenna
and equipment you can imagine," including surplus vacuum-tube maritime
units. At his Colchester, Vermont, location he's using a 42-foot vertical,
but others are employing inverted Ls, loops and Marconis, among others.

Raab was a co-author of the article "A 100-W Class-D Power Amplifier for LF
and MF," which appeared in the March-April edition of QEX
<http://www.arrl.org/qex/2006/03/toc.pdf>. He's using an amplifier of that
design for his WD2XSH operations.

The FCC turned down a 1998 petition from the ARRL to create an Amateur Radio
"sliver band" in the vicinity of 136 kHz, but some US amateur licensees have
obtained FCC Part 5 Experimental licenses to research the possibilities of
LF, including transatlantic and transpacific propagation. Amateur Radio
licensees in Europe and elsewhere already have access to 135.7 to 137.8 kHz,
and several hams in Canada have authorization to operate there using Amateur
Radio call signs.