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.
Detailed information can be found at:
https://github.com/pa3gsb/Radioberry-2.x-extensions/tree/master/Radioberry-PA-20W
10W HF linear
This kit was orderd from QRP – Labs
Nice to built a kit after long time…. the documentation provided is very good.
The amplifier is working good.
https://www.qrp-labs.com/linear.html
Besides the amplifier i decided to buy and built the LPF from QRP – Labs.
https://www.qrp-labs.com/lpfkit.html
combining these filters with the Ultimate relay-switched LPF kit from QRP – Labs.
https://www.qrp-labs.com/ultimatelpf
For switching the relays iam using a PCA9555 board; an IO extender controlled via I2C.
This controller is supported by radioberry firmware.
5W Radioberry preamp board.
The preamp board can be clicked on top of the radioberry.
This results in a nice setup with a long time ago built 100W amplifier
https://github.com/pa3gsb/Radioberry-2.x/wiki/Radioberry-preamp
Iam using this setup with a amplifier i built some years ago, the amplifier does contain the LPF filters.
Have fun
73 Johan
PA3GSB