ARRL

COOPERATION CURBS "WIRELESS MODEM" QRM

ARRL Lab Supervisor Ed Hare, W1RFI, says the League received reports in mid-December about persistent interference on the low end of 80 meters and on other bands. The interference, consisting of discrete, somewhat noisy and drifting carriers, typically showed up around 3520 to 3530 kHz, but harmonics have been reported as high as 20 meters. ARRL Lab tests verified that the devices pose a serious QRM problem on the lower part of 80 meters and possibly on other bands.

FCC rules permit the unlicensed devices to radiate signals on HF of up to 30 uV/meter, even on an amateur band. Device operators--TCI in this case--must correct any resulting interference, however.

TCI Senior Engineer Tony Werner said TCI plans to eliminate the 3.52 MHz wireless jacks it's installed "as expediently as possible" by replacing them with 3.3 MHz units or by running a hardwired telephone connection. TCI will immediately replace units that cause interference and automatically replace other 3.52-MHz units during routine customer service and plans to use nothing but 3.3-MHz units in the future. Hams experiencing harmful interference they believe is related to these devices should contact their local TCI office. TCI says it will be at least a few weeks before it has service information and replacement units on hand.

Phonex says it's made the necessary production changes to move the operating frequency of its units to 3.3 MHz. If one of its units causes interference, he said, Phonex will retune or replace it. Hams can contact Phonex Customer Service at 800-437-0101.

"Both companies have been refreshingly cooperative," said Hare, who--as his W1RFI call sign reflects--is the League's point man for interference issues. "If every RFI problem that involves Amateur Radio could be fixed so quickly, I would probably be out of a job."

Hare said hams with questions about this issue may contact him directly at ARRL HQ at 860-594-0318; e-mail ehare@arrl.org.