Expert Electronics SunSDR2 DX User manual

HF output power check
1. Check the output power with Tune mode and dummy load.
Set Tune slider to 100%, on HF bands you should have about 100W with current about 20А.
If the current is lower, then do the following:
Set Drive=0
Press MOX
Current should be about 4.7А, if it's lower, then most likely one of the transistors got burned,
it should be replaced.
2. Open the TRX
Unscrew 4 screws on the front panel, remove the metal panel and plastic panel;
Unscrew 2 top screws on the rear panel;

Grip the front of the heatsink and pull it for 2 cm. PCB will be extracted with the heatsink;
Pull the cable down with the pincer;

Pull the heatsink till the middle of the case, making sure that cables that connect both parts
are OK.
Now disconnect these 3 cables from the SDR board.
Disassemble the TRX, pull out the heatsink and then pull out the SDR board out of the case.

3. Connect a 50Ohm –100W dummy load and go to TX with 100% Drive level.
4. Check the HF voltage on the XS2P connector, it should be around 1V.
5. Check RD16 and RD100 transistors to make sure they are not short-circuited.
6. Then do the output power check according to the picture below.
RD16 red contacts (gates) transistors input.
RD16 yellow contacts HF amplitude should be increased in comparison to red contacts.
RD100 green contacts (gates) transistors input.
RD100 blue contacts HF amplitude should be increased in comparison to green contacts.