For those familiar with WSJT-X, the use of SlowJT9 should be pretty selfexplaining. But keep in mind that the funcionality is not completely identical to WSJT-X.
After launching SlowJT9 a pop up window will appear that will allow you to load the content of a ADIF (ADI or ADX format) logbook:
The logbook must at least have following fields:
- CALL: the contacted station's callsign.
- BAND and/or FREQ: QSO band and/or QSO frequency in MHz. If the QSO band is found the QSO frequency will be ignored, otherwise the QSO band will be derived from the QSO frequency.
- MODE: QSO mode.
Click on
to select a log. Next select the band and mode(s). Only QSOs with this band and mode(s) will be loaded from the log.Mode:
- JT9: all JT9 submode QSOs will be loaded.
- JT9-1 .. JT9-10: only the selected JT9 submode QSOs will be loaded.
- Digi: all JT and FT mode as well as PSK, RTTY and WSQ mode QSOs will be loaded.
- Any: all QSO's will be loaded regardless of the mode.
Load the log by clicking on
or continue without loading a log by clicking on .
After launching SlowJT9 for the first time a "Failed to read settings" warning will appears as the settings file is not yet existing. Before you can use the application for transmitting you have to enter some information. Therefore click on settings:
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Station: In order to enable transmitting it is obligatory to enter a valid call and a 4 or 6 digit WW locator (eg. JO20 or J020IX). For PSKReporter spotting a 6 digit locator is required. If the entries are valid the background colour will change from red to cream. Optional the difference between the computer clock and UTC can be set. Confirm the settings by clicking on or leave without changes by clicking on . |
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Radio: The transmit/receive switchting can be done by VOX or PPT via the RTS or DTR pin of a serial port. The default setting is VOX. If RTS or DTR is choosen you must select a serial port. If a serial port is selected DTR and RTS can be assigned either as PTT or as alert. If a serial port pin is assigned as alert it will become high if any alert message is received (see alert below for more details). It is up to you drive whatever you want via this pin. In case of an alert the background colour of the date & time display will turn red. Click on the date & time display to reset the alert. Optional a TX delay (not effective if VOX is choosen) and/or watchdog timer(1) (up to 99 minutes, 0 = no watchdog timer) can be set. Confirm the settings by clicking on or leave without changes by clicking on . Note that for PTT switching via a serial port in most cases an interface between the computer serial port pin and the transmitter PTT input is required: |
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Audio: Select the correct input (receive) and output (transmit) channel of the soundcard. In general these should be the same as used for WSJT-X. Confirm the settings by clicking on or leave without changes by clicking on . |
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Mode: Select the mode you want tu use:
Properties:
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Save: Select what you want to save:
Confirm the settings by clicking on or leave without changes by clicking on . |
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Reporting: PSK reporter: Spotting of the received signal to PSKReporter.info(4) can be enabled / disabled. If you want to spot to PSR Reporter as listener only (SWL) an ID must be entered. UDP broadcast: UDP broadcast allows an application to send messages to all computers in a LAN. In case of SlowJT9 all decoded messages will be broadcasted. You need to give:
SlowJT9 Monitor can be downloaded here. Confirm the settings by clicking on or leave without changes by clicking on . |
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Alert: Alert if: Select what messages will trigger an alert and will be UDP broadcasted:
The US state of a call is determined using the WAS.DAT(5) file. Both files can be found in the "tables" folder. Update at startup: Select what files will be updated when launching SlowJT9:
Confirm the settings by clicking on or leave without changes by clicking on . |
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Front End Mixer: The resampling and decoding process limits the maximum RX audio frequency to 4980 Hz for JT9-1, 2240 Hz for JT9-2, 840 Hz for JT9-5 and 415 Hz for JT9-10. This can be inconvenient if a higher RX audio frequency is needed to fit the signal in the passband of a narrow filter. This can be fixed by using the Front End Mixer that downconverts the incoming audio signal (fOUT = fIN - fLO). E.g.: if you want to downconvert the 1200..1400 Hz incoming audio to 400..600 Hz the local oscillator frequency must be set to 800 Hz. Be aware that:
![]() Confirm the settings by clicking on or leave without changes by clicking on . |
After setting all required parameters you are ready to use SlowJT9.
- Open this help file.
- View the "must read" message. Please read and understand this message before using SlowJT9.
- Open the settings, see above.
- Open the spectrum window, see further.
- Band activity window. All messages received within the audio bandwidth(1) are displayed here. CQ messages have a green background colour, messages that contain your call have a red background colour and alert messages have an orange background colour.
- : click to tune / stop tuning (toggle function).
- : click to stop the transmission instantly ("emergency stop").
- : click to enable / disable transmitting (toggle function).
- : click to erase alle messages in the RX frequency window, double-click to erase all messages in the band activity window.
- Check this box if you want to transmit the first cycle(2), uncheck to transmit the second cycle(2).
- Check this box if you only want to change your RX frequency if you click on a call in the band activity or RX frequency windows. If unchecked both RX and TX frequency will change.
- DX call field. Enter the DX call here, either by typing or double-clicking in the band activity window or RX frequency window. The text colour will turn red for a new callsign (not worked before). The background colour is red if the DX call is missing or invalid and will turn to cream for a valid call.
- Audio input level bar.
- Approximate distance (km). Is only displayed is the locator grid is known.
- Dial frequency, enter the frequency in Hz en press [enter]. Required only if you want to spot to PSKReporter.info(4). Changes will become effective only after pressing [enter] or 5 seconds of no keyboard activity! The background colour is red for an invalid input, green for a valid input and cream is the input is effective.
- Audio input level display. The background colour is red in case of overload and orange if the level is too low.
- Mode display (JT9-1, JT9-2, JT9-5 or JT9-10).
- Interrupt occupancy. The soundcard data is loaded and handled every 200ms. The interrupt occupancy indicates the percentage of time spent on the interrupt handling. The background colour is green for < 25%, yellow for 25..50%, orange for 50..75% and red for > 75%.
- Cycle progress bar. The colour is red for TX, green for RX and yellow if idle. In addition the current status, and in TX the current transmitted message, is displayed.
- DXCC entity (main prefix). Only shown if a valid DX call is available. The text colour will turn red for a new DXCC entity.
- Date & time display. Make sure that time is set to UTC, either by setting the computer clock or bu setting the UTC difference in the settings (see above).
In case of an alert the background colour of the date a time display will turn red. Click on the date & time display to reset the alert. - Log DX call. This will add the DX call to the list of worked stations and eventually update the worked DXCC and/or US States lists. But it will NOT add anything to your logbook!
- TX audio frequency field. The frequency must be within the allowed audio range(1). The frequency can be changed by typing or using the up/down arrows. Changes will become effective only after pressing [enter] or 5 seconds of no keyboard activity! The background colour is red for an invalid input, green for a valid input and cream is the input is effective. Unless the "hold TX frequency" box is checked the frequency will also be changed by double-clicking on a message in the band activity or RX frequency window.
- RX audio frequency field. The frequency must be within the allowed audio range(1). The frequency can be changed by typing or using the up/down arrows. Changes will become effective only after pressing [enter] or 5 seconds of no keyboard activity! The background colour is red for an invalid input, green for a valid input and cream is the input is effective. The frequency will also be changed by double-clicking on a message in the band activity or RX frequency window.
- Check this box if you want to ommit the exchange of the WW locator if responding to a CQ call. Instead you will immediately send the report.
- Watchdog timer(2) countdown display, only active if the watchdog timer is enabled. The watchdog timer can be reset by clicking on this display.
- Report field. The report must be in the range of -50 to +49 dB. The report can be set or changed by typing or using the up/down arrows. The report will also be changed by double-clicking on a message in the band activity or RX frequency window. The background colour is red if the report is missing or invalid and will turn to cream for a valid report.
- : click to set the RX frequency equal to the TX frequency.
- : click to set the TX frequency equal to the RX frequency.
- Free message field. You can enter up to 13 characters. Allowed charachers are 0..9 A..Z space - @ # < > ? . / +. Double-click to clear this field.
- Structured message field. Messages are generated by clicking on one of the buttons or on a message in the band activity or RX frequency window. You cannot type in this field.
- Check this box to transmit the structured message.
- Check this box to transmit the free message.
- Audio output level slider. Use it to adjust the audio ouput level.
- Structured message buttons. Click on one of there buttons to generate a structured message. Structured messages can only be generated if the required information (DX call and/or report) is available.
- Current cycle(3) display. While for JT9(-1) it is very straighforward to know the current cycle (even minute = 1st cycle, odd minute = 2nd cycle), this is not so for JT9-2 and JT9-5. So for your convenience the current cycle is displayed.
- RX frequency window. All messages received on (or very close to) the RX frequency are displayed here. CQ messages have a green background colour, messages that contain your call have a red background colour.
- Cycle length of received message: 1 = JT9(-1), 2 = JT9-2, 5 = JT9-5, X = JT9-10.
- Minimize the application
- Close SlowJT9.
Spectrum window:
- Close the spectrum view window.
- Lower frequency limit adjustment (100 - 4900 Hz in 100 Hz steps).
- Upper frequency limit adjustment (200 - 5000 Hz in 100 Hz steps).
- TX frequency marker. Any frequency limits will be shown as a gray bar.
- RX frequency marker. Any frequency limits will be shown as a gray bar.
- Frequency axis (in Hz).
- Gain / offset slider.
- Waterfall display. Click on the waterfall display to set the RX frequency, double-click to set the TX and RX frequency.
- If "Gain" is selected (green background colour) the slider will adjust the gain. Click to select.
- If "Offs" is selected (green background colour) the slider will adjust the offset. Click to select.
- If "AGC" is selected (green background colour) the gain will be automaticaly adjusted. Click to enable / disable (toggle function).
- Signal level to colour conversion column. Can be adjusted by changing the visual gain and noise reference level.
- "Black level" offset. Any signal below this level will be black on the the spectrum display.
- Spectrum display. Click on the spectrum display to set the "black level" offset.
(1) The default audio bandwidth is 200 - 1400 Hz for JT9-1 and JT9-2, 200 - 843 Hz for JT9-5, 200 - 416 Hz for JT9-10. This limitations can be discarded (Settings → Mode).
(2) The cycle duration is 1 minute for JT9(-1), 2 minutes for JT9-2, 5 minutes for JT9-5 and 10 minutes for JT9-10. The first cycle starts at the full hour and from then on first and second cycles follow each other alternately:
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(3) The watchdog timer, if active, will stop transmission when it trips. The time can be set between 0 (not active) and 99 minutes. The watchdog times can be reset by clicking on the watchdog timer countdown display. It is also reset by initiating a generated message.
(4) In order to send spots to PSKReporter.info:
- The computer must be conntected to internet.
- "Enable PSK Reporter spotting" must be enabled (Settings → PSK Reporter)
- Either a valid callsign (Settings → Station) or a PSK Reporter ID (Settings → PSK Reporter) must be entered.
Important: JT9-2, JT9-5 and JT9-10 spots can only be seen at PSKReporter.info if "JT" or "all modes" is selected. If "JT9" is selected only JT9-1 spots will be shown.

(5) WAS.DAT file:
The WAS.DAT file is used to determine the US State of a call. It was created based on the US MF active operator list by Ralph, W0RPK.
This file is in plain text, with one callsign preceded by the state (2 character abbreviation) + a single space per line.
Eg:
AL N4WLO
AK KL7L
AZ K7PO
CA NU6O
CA N1VF
CA KR7O
...