An RTTY “Mêlée” and a Quick Ferrite Solution to a Band-Specific problem

The “TARA RTTY Mêlée” is a daylong RTTY sprint organized by the Troy Amateur Radio Association from Troy, NY. (http://www.n2ty.org/seasons/tara_melee_rules.html). Its last occurrence was yesterday.

My setup for RTTY QRP is quite simple: the ICOM 703 operating in SSB-D mode is interfaced via the Signalink USB and the ICOM CT-17 with a T-60 ThinkPad Laptop running Windows XP and Fldigi. The Fldigi Macros are used for the exchanges. FLdigi is also used for the RTTY decoding and for keeping a log later used to export ADIF and Cabrillo files. I had used this same setup in the past and was not expecting any glitches.

RTTY signals were detected only in the 20m and 15m bands. Making contacts in 20m was a breeze. After logging most of the stations that Fldigi could decode in 20m I switched to 15m. In my first attempt I noted a hesitation in the transmission but my callsign was successfully sent and the other station (one from Texas) did send a reply. As I attempted to send my exchange Fldigi locked and the contact had to be dropped.

I had experienced something similar long ago while operating in Hellshreiber mode but at the time the problem was related to the ground cable having become disconnected from the tuner, which now was clearly not the case. However, I seldom operate digital modes in the 15m band. Hence, I favoured the idea that this could be a band-specific problem causing some RF to find its way into the computer.

The computer connects to the transceiver indirectly via two cables plugged to two of its USB ports: a coaxial cable leading from the ICOM CT-17 and another one connecting to the Signalink. A small loop in each of these cables and two ferrite clamps, one applied to each, immediately solved the problem.

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I was then able to complete a few more QSO’s in the 15m band, including one with the same Texas operator who graciously replied to my call a second time, this time for a complete QSO.

Suddenly, a call for lunch with the family offered a better option for quality time, which brought my participation in the “mêlée” to an abrupt halt. After a couple of hours, I had logged 14 stations in 9 states (CO, FL, IA, IL KY, NC, TX, WA and WI) and two DXCC’s: DL and YV.

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