Joselin -Vermogensversterker 1200-1320 MHz 13W Hoogefficiënte Signaalversterker voor GNSS-Ontvanger WIFI Drone Satellietsignaalradio

When it arrived, the device did not work correctly.The quiescent current was to low (120mA), max power was ~5..10W which is more or less ok, but it seems to work in class-C. With less as 0dBm input, almost nothing comes out. Sometimes it has spurious oscillations.This amplifier is offered by multiple manufacturers/brands (?). I had the luck that a friend owns a good one, and after comparing the devices, we found a few differences:- Two decoupling capacitors were missing (100n)- Four screws were missing (needed for grounding)- In the 'good' amp, we found additional copper under the power amplifier, which was soldered thoroughly to the PCB- A connection (PCB trace!) between two resistors (between a 5k1 and a 1k0 R, driving Vgs2) was missing. This was the main problem. Note that there is just no trace here at the PCB! The 1k0 resistor just floats, the Vgs2 is grounded via the 5k1. Incredible, did these people never really check or test the PCB?After adding the missing C's, adding the missing screws and making a connection between the two resistors, the amplifier works way better!The quiescent current is 180mA, still lower as expected (330mA on the 'good' one, also according to the datasheet). Output power is >10W, I think, while drawing 1.2A @ 28 volts.The gain is almost flat from 1240 to 1300 MHz, and it gives >10 W on all frequencies.After fixing the issues, it works, so I will not return it.However, you should, of course, buy a 'good' one, not this one.