Switch to an External 10 MHz Reference

This page explains how to select an external 10 MHz reference clock on a connected FLEX-8600. Use an external reference when you have a GPS-disciplined oscillator or other precision 10 MHz source and want the radio to lock to it instead of its internal oscillator.

Before you start

• AetherSDR must be connected to the radio. The Radio Setup dialog requires an active radio connection.
• Your external 10 MHz reference signal must be connected to the rear-panel REF IN port on the FLEX-8600 before switching the source.

Steps

1. Click Settings > Radio Setup... to open the Radio Setup dialog.
2. Click the RX tab.
3. Locate the 10 MHz Reference Source: combo box.
4. Select External 10 MHz from the combo box. To return to the built-in oscillator, select Auto.

What each control does

Control	Kind	Valid range / Behavior
10 MHz Reference Source:	Combo box	Auto | TCXO | GPSDO | External 10 MHz. Options shown depend on hardware installed and on the current oscillator state reported by the radio. The combo is populated dynamically: TCXO appears when the hardware has a TCXO or when the radio currently reports TCXO as its active state; GPSDO appears when a GPSDO is present; External 10 MHz appears when an external reference is detected or currently active. Lock status is shown alongside the combo and updates live (see below).
Lock status label	Indicator	Shows the current oscillator source and lock state. When Auto is selected, the label reads Auto -> <active source> to indicate what the radio has chosen. When the selected source differs from the active state, both are shown (e.g. TCXO -> GPSDO). Appends Locked (green) or Unlocked (red). If External 10 MHz is selected but no external signal is detected, the label appends (not detected). While waiting for the radio to report status the label reads Waiting for oscillator status (grey).
TX Follows Active Slice	Push button	TX follows the active slice. Mutually exclusive with Active Slice Follows TX. Disabled automatically during Split operation.
Active Slice Follows TX	Push button	Switches the active slice when TX moves externally (e.g. WSJT-X or CAT). Mutually exclusive with TX Follows Active Slice.
Voice / CW / Digital filter sharpness sliders	Slider (0–3)	Sets filter sharpness (0=lowest latency to 3=sharpest) per mode; slider is disabled when Auto is enabled. Commands sent as radio filter_sharpness <mode> level=<N>.
Auto (Voice / CW / Digital)	Toggle button	Enables automatic filter-level selection for that mode; disables the manual sharpness slider. Commands sent as radio filter_sharpness <mode> auto_level=1.
Connect / Disconnect (TGXL)	Push button	Opens/closes direct TCP connection to the TGXL on port 9010. Saves IP and port to TGXL_ManualIp and TGXL_ManualPort on connect so AetherSDR auto-reconnects on startup. Required to recover TUNE on firmware 4.2+. When connected, the TUNE button sends the native autotune command directly to the TGXL instead of the radio-side path broken in firmware 4.2. If the IP field is empty and the radio has discovered the TGXL, the discovered IP is pre-filled.
Connect / Disconnect (PGXL)	Push button	Opens/closes direct TCP connection to the Power Genius XL (default port 9008). Saves IP and port to PGXL_ManualIp and PGXL_ManualPort.
Connect / Disconnect (Antenna Genius)	Push button	Opens/closes connection to the Antenna Genius (default port 9007). Saves IP and port to AG_ManualIp and AG_ManualPort. The row is hidden from "Connected" status when a ShackSwitch (rather than a standard Antenna Genius) is the connected device.
Connect / Disconnect (ShackSwitch)	Push button	Opens/closes connection to a ShackSwitch antenna switch via the AG UDP/TCP protocol on port 9007. Saves IP to SS_ManualIp and port to SS_ControlPort. ShackSwitch is detected by the ShackSwitch field in the AG broadcast beacon. Auto-discovery via UDP also works without this row. Row hidden from "Connected" status if an Antenna Genius (non-ShackSwitch) is the connected device.
⚙ Web UI (ShackSwitch)	Push button	Opens the ShackSwitch device's local web configuration interface in the system browser. Uses the beacon's webPort if > 1024, otherwise falls back to SS_WebPort or port 5000.
Select Installer...	Push button	Opens a file picker that accepts .msi (FlexRadio v4.2+ WiX installer), .exe (older self-extracting installer), or a pre-extracted .ssdr firmware file. The firmware stager auto-detects format from the first 8 bytes (OLE/MSI magic vs PE/COFF MZ) and extracts the .ssdr without external tools. Label was Browse .ssdr... before v0.9.3.
APD (tab)	Tab	External Adaptive Pre-Distortion sampler configuration — per-TX-antenna selection of the feedback sample port (INTERNAL / RX_A / RX_B / XVTA / XVTB) and an equalizer reset button. Tab is hidden unless the radio reports apd configurable=1. Only FLEX-8x00 series with SmartSDR 4.2.18+ firmware exposes this; 6000-series and pre-4.2.18 radios keep the tab invisible.
ANT1 / ANT2 / XVTA / XVTB sampler combos (APD)	Combo box	Selects the feedback path the radio uses to sample the outgoing RF for APD training for that TX antenna. Default INTERNAL. Choose an external RX/XVTR input when driving an external linear amplifier. Options are populated live from the radio's apd sampler sub-object. Falls back to INTERNAL if the radio reports an unrecognised value.
Equalizer Reset (APD)	Push button	Sends apd reset to the radio, clearing all per-antenna APD training data so adaptation starts fresh.
Themes (tab)	Tab	UI customization tab — currently hosts the Slice Colors section.
Use Aether defaults / Custom colors	Radio button	Switches the slice color scheme between the built-in AetherSDR palette and a fully custom per-slice set. Backed by SliceColorManager::useCustomColors().
Slice A–H color buttons	Push button	Click any lettered button (A–H) to open a color picker and assign a custom color for that slice. Changes are visible immediately in VFO widgets, panadapter overlays, and CAT channel badges. Buttons are disabled when Use Aether defaults is selected. Up to 8 slices (kSliceColorCount).
Reset All to Defaults (Themes)	Push button	Resets all custom slice colors to the built-in AetherSDR palette.

Firmware update (Radio tab)

Starting in v0.9.3, the firmware update workflow no longer downloads installer files automatically. When Check for Update finds a newer version, the status label instructs you to download the SmartSDR installer from flexradio.com and then use Select Installer... to stage it locally. The button previously labelled Browse .ssdr... is now labelled Select Installer... and accepts .msi, .exe, and .ssdr files.

How to update firmware

1. Click Settings > Radio Setup... to open the Radio Setup dialog.
2. Click the Radio tab.
3. Click Check for Update. AetherSDR contacts FlexRadio's update server and reports the latest available version in the status label.
4. If an update is available, download the SmartSDR installer from flexradio.com.
5. Click Select Installer... and choose the downloaded .msi, .exe, or pre-extracted .ssdr file. AetherSDR auto-detects the format and extracts the firmware. The status label shows preparation progress.
6. When staging completes, click Upload Firmware. A progress bar and status label track the upload.

Frequency calibration (RX tab)

As of v0.9.2.1, the frequency calibration controls on the RX tab are always visible, regardless of whether a GPSDO is installed. When a GPSDO is present, the status label reads "GPSDO installed. Manual frequency offset calibration available." (shown in green). When no GPSDO is present, the label reads "Manual frequency offset calibration available." (shown in amber). In previous versions, the calibration controls were hidden when a GPSDO was detected.

Calibration controls

Control	Kind	Behavior
Cal Frequency (MHz):	Text field	Frequency used for manual calibration. Enter the exact frequency of your reference signal in MHz.
Start	Push button	Sets the calibration frequency, resets freq_error_ppb to 0, then starts the calibration sweep. The button is disabled and shows "Busy" while calibration is in progress. A status label beside the button shows the current state (Starting…, progress text, or result). The field must not be empty; if it is, the status label prompts you to enter a frequency before proceeding.
Freq Offset (ppb):	Spinbox	Manual frequency offset in parts per billion. Adjust if you need to apply a known offset without running the automated calibration sweep.

How to run a calibration sweep

1. Click Settings > Radio Setup... to open the Radio Setup dialog.
2. Click the RX tab.
3. Enter the exact frequency of your reference signal in the Cal Frequency (MHz): field.
4. Click Start. The button becomes disabled and shows "Busy". Watch the status label for progress.
5. When the sweep finishes, the status label reports the result and the Start button re-enables.

Oscillator source combo behavior (v0.9.7)

In v0.9.7, the 10 MHz Reference Source: combo box is populated dynamically based on the live state the radio reports, rather than solely on hardware-presence flags detected at dialog open time. The following rules apply:

• Auto is always present.
• TCXO appears if the radio has a TCXO installed, or if the radio is currently reporting TCXO as its oscillator state, or if TCXO was previously selected.
• GPSDO appears if a GPSDO is installed, or if the radio is currently reporting GPSDO as its oscillator state, or if GPSDO was previously selected.
• External 10 MHz appears if an external reference is currently detected, or if the radio is reporting it as the active state, or if it was previously selected. The label was External in versions before v0.9.7.

When the combo is opened before the radio has reported oscillator status, all options that match the current setting or a previously selected value are retained so no selection is lost.

The lock status label to the right of the combo also gains additional detail in v0.9.7:

• When Auto is the configured setting, the label shows Auto -> <resolved source> to make the radio's actual choice visible.
• When the configured setting and the active state differ (for example, during a source transition), the label shows <configured> -> <active>.
• If External 10 MHz is selected but the radio reports no external signal present, the label appends (not detected).
• Before the radio has sent any oscillator status, the