This is an early design sketch of a 6m WSPR beacon.
Key Points
- 25 MHz HCI 0.5ppm TCXO powering the Si5351 module instead of the 26 MHz TCXO. If this fails, we can use a 10 MHz OCXO instead (a bit out of spec but works fine).
- Tokmas CID10N65F GaN FET should work @ 50 MHz
- TI UCC27614 or Onsemi NCP81074 gate driver
Status
Results: To be built and tested soon!
Updates
Update: The HF-PA-v10 PCB was built and tested with RD15HVF1-501 (GSD pinout MOSFET that we had lying around). 14V @ drain and 5V to gate driver produces ~4W RF output @ 50 MHz (6m). Not bad!
The simplicity, ruggedness and performance of this design is quite remarkable. Please see WSPR Tx by G0UPL for an alternate older design. We are quite happy with the reduced cost and infinitely more ruggedness of our design as compared to this Ultimate 3S powered 5 Watt power amplifier work.
On the internet, you will find stories of how fragile the Ultimate 3S's
BS170-based PA is. On the other hand, it appears to work up to the 2m band. We
want a BS170 that is not a BS170 😅. Of course, we can choose
RD06HVF1-501 / RD01MUS1 / RD00HVS1 as drivers, but these parts are neither
widely available nor the cheapest. Instead, we hope that using 2SK3475 (from
LCSC) as the driver will allow our design to operate on 2m at full power.