Set the TX audio low-cut frequency¶
Use the Low Cut control in the Phone applet to raise the lower edge of the TX audio passband, cutting rumble, breath noise, or low-frequency interference from your transmitted signal.
Before you start¶
- Connect to a FLEX-8600 radio. The Phone applet requires an active radio connection.
- Make sure the Applet Panel is visible. If it is not, click
View > Applet Panelto show it.
Steps¶
- Click the PHNE tray button on the right sidebar to open the Phone applet.
- Locate the Low Cut section in the TX filter area at the bottom of the applet.
- Click < to decrease the low-cut frequency or > to increase it. You can also scroll the mouse wheel over the value display to step in either direction.
- Read the current value in the numeric display between the two buttons. The default is 50 Hz.
How the step buttons work¶
Each click of < or > snaps the low-cut frequency to the nearest multiple of 50 Hz in the chosen direction, rather than adding or subtracting a fixed 50 Hz from the current value. For example, if the current value is 87 Hz, clicking > sets it to 100 Hz and clicking < sets it to 50 Hz. If the value is already an exact multiple of 50 Hz, the buttons move it to the next multiple in the chosen direction.
This means a single click always lands on a clean 50 Hz boundary regardless of the starting value.
What each control does¶
| Control | Default | Valid range |
|---|---|---|
| Low Cut < | — | Snaps down to next lower 50 Hz multiple |
| Low Cut > | — | Snaps up to next higher 50 Hz multiple |
| Low Cut value display | 50 Hz | 0 Hz to (high-cut − 50 Hz), step 50 Hz |
Tips¶
- The low-cut value cannot be set higher than the current high-cut frequency minus 50 Hz. If you are near that limit, lower the high-cut first or raise it to create room.
- For SSB voice, a typical low-cut of 100–200 Hz reduces low-frequency noise without noticeably affecting voice intelligibility.
- Because the buttons snap to multiples of 50 Hz, clicking once from any off-boundary value may move the frequency by less than 50 Hz. This is expected behaviour.
Troubleshooting¶
- Low Cut buttons do nothing — Confirm the radio is connected. The TX filter controls require an active radio connection to send filter changes to the FLEX-8600.