Radioberry TX amplifiers.

20W Amplifier

From Deepu, VU3TLD i received a bare PCB board, he designed a PCB based on the developement done by G6ALU.

It took some time to collect all the required components. I had a great time building this amplifier.
Winding the toroids and assembling the 1206 SMD components, these 1206 SMD are large…when you are used to 0603 sizes.

Also doing some mechanical work like tapping the holes for mounting the HF devices.

A big advantage of these devices used here are in a TO220 package which differ, from switching devices,
in that the tab is connected to the source electrode, so in this design are grounded by the PCB and heat sink.
No insulating washers are used when bolting the devicesdown to the heat sink and PCB.

After assembly i attached a 50 ohm resistor at the amp in connecor; setting the bias was going smooth.
But when removing the 50 ohm resistor the amplifier started to oscillate… but looking back in some direct mails
from Deepu i could have found the warning; i had to ground the HF-in and HF-out connector.