If your radio is "crashing" when transmitting -- either turning completely off, or powering off with "2-RED Flashes" of the power button and rebooting itself -- this is usually a power supply issue, or a radiated or common mode RFI issue:
Let's address potential power supply issues first:
If there is high resistance in your DC power cabling and connections between the power supply and radio, when the radio draws higher amperage under load, when transmitting, it can cause a drop in voltage to the radio, causing the radio to shut down under load. The same issue can occur if the power supply regulator circuitry is malfunctioning, too.
NOTE: The FlexRadio requires between 23 and 29 Amps of current at 13.8 Volts for full power operation. It is higher than many legacy analog radios, due to the current requirements of the multiple computer processors inside the radio. If you are using a "traditional" 20 Amp power supply, it may not have enough current supply capacity to run the FlexRadio at full output, especially on CW, RTTY, or other Digital Modes like FT8. If the power supply is over-taxed, it will not be able to maintain proper operating voltage under load, and the radio will crash.
Diagnosing Power Supply and Connection Issues:
The first step in troubleshooting is to verify that the radio is receiving sufficient voltage under load.
Be sure that all of the PowerPole and other connections between the power supply and radio are clean and securely connected. Especially check any in-line fuses or power distribution boxes you have in line.
Use a little 91% Isopropyl Alcohol or a bit of "De-Ox-It" to clean all Power Pole connections. Insert and remove Power Pole connectors multiple times to allow the "self-cleaning" spades to scrape each other clean.
It is recommended to give the power cable a half-turn around the back leg of the radio to give it some strain relief. (Otherwise, the weight of the power cable hanging on the Power Pole connector can sometimes torque the connector enough to make a loose connection, which will add resistance to the power feed.)
Check the Voltage at the radio end of the power cable. For optimum operation, we recommend 13.8 VDC.
IF this does not resolve the issue: If you have a spare power supply, connect it up directly to the radio, bypassing any in-line fuses or distribution blocks. Test again using the spare power supply.
If it is not a Power Supply / Voltage Drop issue:
After verifying the power supply is not the problem, you need to investigate RF factors causing the shutdown.
The most common type of RF issue is common-mode currents on the coax shield taking a path to ground through one of the cables connected to the radio. It takes a methodical approach to determine what is causing the problem.
These two documents address the diagnosis and mitigation of radiated and common-mode RFI (Radio Frequency Interference) issues:
How to Diagnose RFI and Common Mode RF Interference When Transmitting – FlexRadio
How to Mitigate Common Mode Interference – FlexRadio
This document addresses the proper grounding of Amateur Radio Stations:
Grounding Systems in the Ham Shack - Paradigms, Facts and Fallacies – FlexRadio
If none of these steps resolve the issue, please open a HelpDesk ticket so that we can address the issue further.
How to Submit a Request for Technical Support – FlexRadio