WSJT-X 2.1.0-rc5


To: Users of WSJT-X -- especially those interested in radio contesting
From: WSJT Development Group

By now most of you know about the FT4 protocol under development for eventual release in WSJT-X 2.1.0. The new mode is particularly optimized for use in radio contesting.

FT4 is mostly like FT8, but is 2.5 x faster, uses 1.8 x the bandwidth, and is 4.6 dB less sensitive. Many other details are summarized in "The FT4 Protocol for Digital Contesting", available here:
Links to translations in other languages are available on the WSJT-X web page:

Release candidate WSJT-X 2.1.0-rc5 is intended for beta-testing through June 7, 2019. Please note that the FT4 mode should NOT be used in the ARRL June VHF QSO Party (June 8-10) or ARRL Field Day (June 22-23).

We have done our best to provide suggested operating frequencies for the test period consistent as far as possible with world-wide band plans and existing usage. Please note that thanks to good user feedback, some of these frequencies are different from those suggested in the document linked above.

Default frequencies currently recommended for FT4 are as follows:

Band MHz Notes
80 3.575 (3.568 MHz in Region 3)
40 7.047
30 10.140
20 14.080
17 18.104
15 21.140
12 24.919
10 28.180
6 50.318
2 144.170

FT4 is designed for contesting, but it will likely find some use for normal QSOs as well, especially during the beta test period. In the coming month we hope to receive useful feedback on the user interface, message sequencing, interaction with logging programs, etc. Probably it's best to use "normal" (non-contest) messages except during the mock-contest practice sessions scheduled for 0000 - 0100 UTC on May 9 and May 14, and (if needed) June 5.

Downloadable installation packages for WSJT-X 2.1.0-rc5 under Windows, Linux, and macOS are available on the WSJT-X web page:

Windows users will discover that WSJT-X v2.1.0 has been made available as a 64-bit MS Windows build for 64-bit versions of Windows since Vista. This veraion has one known defect. The audio input device level will be reset to 100% when WSJT-X is started, when the input audio device is changed, and when switching to a new configuration. This is a Qt framework defect that we have reported and is being fixed in a future release; until then users should take care to set the device audio level back to 0dB or lower depending on requirements. Note that many sound cards and chips have real gain ahead of the ADC, as much as 14dB, which will be turned to the maximum due to this defect and is usually undesirable when using WSJT-X.

Despite this annoying defect, we recommend the 64-bit version of WSJT-X on MS Windows as it has significant advantages in decoding speed.

-- 73 from Joe, K1JT; Steve, K9AN; and Bill, G4WJS

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