[UPDATED 2019-06-03 @ 1915 UTC] The WSJT-X Development Group has released yet another new beta version of the FT4 protocol now available for testing in WSJT-X 2.1.0-rc7. The FT4 included in this “release candidate 7” version is not compatible with any previous release. Over the weekend, the developers had made WSJT-X 2.1.0-rc6 available for downloading and testing but “because of a serious bug,” pulled that version not long afterward. 

“We are aware of a serious issue with this [-rc6] release,” Bill Selwood, G4WJS, of the WSJT-X Development Group, said on June 2. “Many users are experiencing a crash on attempting to start this version. The issue is not happening for everyone, but it appears to be present on all supported platforms.” Some users of release candidate 6 expressed satisfaction with the new version.

The developers advised FT4 enthusiasts to stop using WSJT-X 2.1.0-rc5 and switch to the latest -rc7 beta version to take advantage of other program corrections and enhancements.

A short mock contest session to wring out the contesting features of FT4 is scheduled for June 4, 1900 UTC, through June 5, 0100 UTC.

“Get on the air whenever you can during this mock contest session, using dial frequency 7.090 or 14.080 MHz, as appropriate to the time of day,” the announcement advised. “As in previous tests, be sure to check “RTTY Roundup messages” on the Settings | Advanced tab.”

Changes, improvements, and bug fixes that have been made since WSJT-X 2.1.0-rc5 include:

• T/R sequence length increased from 6.0 to 7.5 seconds
• Symbol rate decreased from 23.4375 to 20.8333 baud
• Signal bandwidth decreased from 90 Hz to 80 Hz
• Allowable time offsets –1.0 < DT < +1.0 second
• TX 4 message with “RRR” now allowed, except in contest messages
• Audio frequency now sent to PSK Reporter
• Third decoding pass added
• Improved sensitivity: Threshold S/N is now –17.5 dB
• Improved S/N calculation
• In FT4 mode, Shift + F11/F12 moves transmit frequency plus or minus 100 Hz

Release candidate WSJT-X 2.1.0-rc7 will be available for beta-testing through July 21, 2019. It will not be usable during the ARRL June VHF Contest or during ARRL Field Day, and it will permanently cease to function after July 21, 2019. “If all goes according to plan, by that time we will have made a General Availability release of WSJT-X 2.1.0,” the announcement said.

Known Issues in WSJT-X 2.1.0-rc7

The developers note that they are aware of the following bugs or anomalies in release candidate 7. The 64-bit executable for Windows resets the audio input gain to 100% on program startup, when the input audio device is changed, and when switching to a new configuration. The recommended temporary workaround, if necessary, is to reset the Windows audio input to the desired level.

Download WSJT-X 2.1.0-rc7 

Downloadable installation packages for WSJT-X 2.1.0-rc7 under Windows, Linux, and macOS are available on the WSJT-X web page.