March 2000 QST

By Timothy P. Hulick, W9QQPSK31 on the Road!Forget your RTTY gear the last time you cruised cross-country? Thanks to theincredible weak-signal performance of PSK31—and a few choice macros—you can take it with you!learned to enjoy mobile DXing as a kid in the ’50s. MyIparents’ 1955 Oldsmobile 98 made the perfect shack onwheels. That’s way back when there really wasn’t anyequipment specifically designed for mobile work. Mobileequipment should be small, lightweight and dc-powered. Thattechnology hadn’t yet been born, and big and heavy was the nameof the game.The bigger it was, the heavier it was, the better it was. That wasthe image of the proverbial mobile rock crusher. A high-voltagepower supply with a 12-V dc input was nearly impossible to findor build because the solid-state devices necessary to support thedesign of something like that just didn’t exist.The predecessor of the modern high-voltage switching powersupply was the WW II surplus dynamotor. They were abundant inthose days and rather inexpensive. One dynamotor easily providedthe 800 V necessary to run a 100-W power amplifier—butnot without the occasional dead battery if the QSO dragged on toolong (5-10 minutes if the engine was turned off).If I remember correctly, the 12-V current drain was somewherebetween 20 and 30 A, plus the motor start-up current required eachtime the PTT button was pressed. As a teenager I lost my drivingprivileges more than once because of unexplained dead batteries.“What dead battery? I didn’t do it!”Full-carrier AM wasn’t effective in busting pileups from thecar—at least not in the dynamotor era! On hot summer days, idlingthe engine was out of the question. That brought along its own setof problems. Reliving the glory days of HF mobiling is fun, butI’m glad that dynamotors are ancient history. Mobile DXing haschanged dramatically.A Mobile TraditionI’ve always had an HF rig in the car, especially after it reallybecame practical. Heath’s line of compact monoband rigs, debutingin the ’60s and early ‘70s, were just what the hobby ordered.I just had to have one for each of the bands on which they wereavailable (80, 40 and 20 meters). I even coaxed the 80-meter versiononto 15 meters because my main objective was to “work DXfrom the car.” It was my ultimate challenge.The modifications were productive and I worked a lot of DX on15 and 20 meters. But because the rigs were monobanders, changingbands meant changing transceivers! Even worse, there was no wayto fight the incredible level of ignition noise that tended to plaguemobile ops in those days. Noise blankers weren’t exactly stock items.My trusty dynamotor was replaced with a Heath solid-stateswitching supply that was far more efficient. I never did end upwith a dead battery while using Heathkit’s model HP-13. I stillhave the thing. It works fine, although I gave the transceiversaway years ago.In the mid-1970s, along came the Atlas 210X. That was theThe author pulls over at a promising location, switches onhis transceiver, opens his laptop computer and works PSK31.first real all-solid-state rig designed for 12 V. It didn’t need a highvoltagesupply of any kind. It was truly the predecessor to today’sultra-compact mobile rigs. It was small, lightweight and great forHF SSB on the move. The best DX I worked with that little rig wasa ZS6 in the spring of 1983 on 15 meters.Today I use a Kenwood TS-440S with a center-loaded whipantenna and have managed to confirm 143 countries since I startedcounting in the early ‘80s. Working DX has become commonplace,especially on 15 meters (the antenna is noticeably moreefficient there).PSK31 on the GoI’ve heard that old-timers such as W6AM used to operate CWwhile mobile on California’s freeways, but somehow that neverappealed to me. I’m not sure I could drive the car, interpret CWand chew gum at the same time.Operating PSK31 under the same conditions is no better, butduring stopovers on long trips, or at least during an overnight stay,PSK31 is just the ticket to great operating opportunities awayfrom home. There are several reasons why. PSK31 is an excellentlow-power mode, and a laptop computer with a suitable soundsystem is the only additional hardware needed.I was introduced to PSK31 in February of 1999 when I workedHB9BRJ on Baudot. Markus said that a new BPSK/QPSK modewas catching on in Europe. Now, BPSK and QPSK aren’t entirelynew, but they were new to Amateur Radio, and G3PLX (PSK31’sMarch 2000 55