Not sure if this is the right place to ask, but I’ve been testing my VGA dongle and I can get a signal output on a scope but after some time it stops. I’ve observed this with fl2k_test, fl2k_signal_generator and my own software; on Linux, Windows and two different PCs. My USB port reaches 157 MS/s too.
not sure if the osmo-fl2k aouthor steve-m is using/following the discourse here. You might want to try filing an issue at Issues - osmo-fl2k - Open Source Mobile Communications - and make soure you post any relevant logs/output before/during and after it the output stops. Specifically I’m wondering about any libusb error messages or kernel usb stack errors logged.