SSPA 1296 MHz - 1200W RF
07.02.2024
For an amplifier for outdoor use in a parabolic antenna, I chose the W6PQL design. Jim offers 650W modules that can be combined to create an amplifier with adequate EME performance. A 90°hybrid, also from W6PQL, is used as the input divider. A tried and tested and proven 90°hybrid by DJ9BV is used to combine the amplifiers at the output. The following pictures show how I imagined the amplifier on paper and how it turned out in reality.
Block diagram of the amplifier. This is how I imagined to make it
And this is what the amplifier looks like. The massive heat sink that forms the base of the box made of aluminium profiles. Inside are two W6PQL modules and the necessary jewellery to connect all the parts of the amplifier.
This is a wiring diagram of the W6PQL modules. More details can be found on Jim's W6PQL website. Jim sells these modules as kits or as finished and revived modules.
MRF 13750H moduls
I milled SMA connectors and coaxial cable holders from copper for screwing to the modules.
I connected the whole amplifier to a 50V/A power supply with a fast electronic fuse and set the idle current of the amplifier. Each module is set to 1,5 A current. This is the current that flows through the transistor when the gate voltage is 2.2 V. Then I connected a DC 50V/60A regulating power supply. For the first test I used 0.5W excitation power. Everything behaved normally and with 1W excitation on the input, the output power was 120W RF. The amplification factor was therefore exactly as expected. Next I increased the excitation linearly up to 11W RF and measured an output power of 1200W RF. The circuits and the whole amplifier are working normally and I was using this SSPA during ARRL EME contest 2023 with full output power CW and Q65.
SSPA used in the dish.