ARRLWeb: ARRL 500 kHz Experiment Kicking into High Gear

Rudy Severns, N6LF, at his WD2XSH/20 setup in Oregon.

The WD2XSH/20 antenna base, showing the radials and tuning coil.

A modified Heath DX-100, seen here standing on end, provides the signal for Paul Signorelli, W0RW, operating as WD2XSH/21 from Colorado. Note the huge coil and substantial capacitor, upper left.

The setup at WD2XSH, operated by Dex McIntyre, W4DEX, in North Carolina

NEWINGTON, CT, Nov 10, 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 this week. "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 claim.

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 instead.

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 frequency!"

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.

A map showing the locations and Amateur Radio call signs of the WD2XSH participants.

500 kHz experimental group Project Manager Fritz Raab, W1FR (left) and Mike Gladu, N1FBZ, adjust the 500-kHz antenna tuner at the base of the 42-foot WD2XSH/14 vertical.