4 and 8 Watt WiFi bi-directional amplifiers are designed for about 10-20 dBm input power. They listening in their input for a relatively strong signal to decide whether turn over to TX state from RX state (and changing over RF switches). Doing this simply rectifying the inrush RF power and leading that into an amplifier IC, in our case the TPH2504 amplifier used.
For QRP operation +10dBm power is many times a dream only, for example my output power after upconversion was about -10dBm… The simple solution for modding EDUP EP-AB007 for non-stop TX mode.
The workaround is the same as the one suggested by George M1GEO in his nice article: https://www.george-smart.co.uk/2019/03/limesdr-edup-pa/
The only difference between his amplifier and my lower cost and lower power 4W that different brand of amplifier IC used. But they looks like 1:1 compatible in function and pinout. I was making a short between PIN4 and 5 in my TPH2504 IC and worked as expected: the amplifier device turned in to non-stop TX state, regardless of the input power applied.
EP-AB007 manufacturer link,
Ali-express link: https://www.aliexpress.com/item/32923651924.html