Andre Kesteloot andre.kesteloot at
Sun Nov 19 15:30:20 CST 2006


The group of Amateur Radio operators researching the radio spectrum in the
vicinity of 500 kHz already have recorded a few successes. The 500 KC
Experimental Group for Amateur Radio <> is operating
under Part 5 experimental license WD2XSH, which the FCC Office of
Engineering and Technology granted September 13 to the ARRL. Project manager
Fritz Raab, W1FR, says WD2XSH participants have been heard across both the
Atlantic and the Pacific as well as all around the US.

"Things took off much faster than I had ever imagined," Raab told ARRL early
this month. "Eleven station are on the air now." Others in the 21-station
group included on the Experimental license continue efforts to cobble
together the transmitting and antenna systems necessary to put out a signal
on what group members call "the 600 meter band."

Raab says the 600-meter signal of well-known low-frequency enthusiast "Dex"
McIntyre, W4DEX, in North Carolina -- operating as WD2XSH/10 -- was copied
October 10 in Germany using very slow-speed CW (QRSS). Other stations have
since duplicated that feat. Rudy Severns, N6LF, operating as WD2XSH/20 from
Oregon, not only is heard regularly throughout the western half of the US
but has been copied in Hawaii and, possibly, in New Zealand, Raab says,
noting that the New Zealand reception was "not sufficiently clear" to make a

While not a part of the experimental group, Ralph Wallio, W0RPK, has assumed
the role of official record keeper and has noted more than two dozen one-way
reception reports of more than 1000 miles. The list included "by ear" CW
reception from Colorado to Massachusetts, nearly 1800 miles. The best
distance as of earlier this week: 4515 miles from Conard Murray, WS4S,
operating as WD2XSH/11 in Tennessee to Germany using QRSS (reception using
computer software).

Operating as WD2XSH/14 from Vermont, Raab says he's managed three QSOs with
his "meager 42-foot vertical" -- New Hampshire, Massachusetts and North
Carolina -- plus reception in Ohio. He envisions at least a secondary
600-meter Amateur Radio allocation from 495 to 510 kHz that would support
Amateur Radio emergency communication via groundwave.

The two-year WD2XSH authorization permits experimentation and research
between 505 and 510 kHz using narrowband modes at power levels of up to 20 W
effective radiated power (ERP). The Midwest stations are limited to 505 to
508 kHz for the time being, Raab notes. The first QSO took place September
21 between the stations in Tennessee and North Carolina — a distance of some
300 miles.

To get on the air, WD2XSH participants have repurposed some older gear and
even some text equipment. Paul Signorelli, W0RW, operating as WD2XSH/21 from
Colorado, has modified a vintage Heath DX-100 transmitter for LF CW
operation. "I match the DX-100 output to a 5-turn link of #10 wire," he
reported in a detailed description of how he was able to get the old rig to
transmit just below the AM broadcast band. Getting "down there" points up
the need to increase physical component size by several orders of magnitude.

"The link is on a 13-inch diameter cardboard hoop," Signorelli continues.
"It slips up and down over the antenna loading coil and is adjusted for
lowest SWR." That antenna loading coil itself is a foot in diameter, wound
with #10 solid, insulated wire. A 30-gallon trash can provides the
weatherproofing for the coil. The DX-100 generates 100 W of RF on 500 kHz.
Signorelli advises against using conventional-sized coax. "This transmitter
will smoke your coax if you have high SWR," he said. He's using hardline

While Raab notes that while the current license cannot accommodate more
participants, he plans to re-evaluate the situation in a year. "At that
time, we may request a revision to the license that makes substitutions for
stations that have not gotten on the air and possibly add some new
stations," he says on the group's Web site. "Substitutes and additions will
be selected based upon their potential to contribute to the experiment." He
cautions, "This is an experimental license, not just ham radio on a new

The experimental group does invite reception reports
<> of transmissions made by group
members. You do not have to be a member of the experimental team to send a
reception report.

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