Our WSPR beacon design works fine even on the 4m band (~70 MHz) . The key is to use a 25 MHz high-quality TCXO, like the 25 MHz HCI 0.5ppm TCXO! Results Challenges 2m WSPR is still out of reach for now - see the following sporadic decodes. Of course, the next challenge is to get 2m WSPR beacons working 100% reliably at a low cost. ...
The usage of ready-made coupled inductors in RF designs was pioneered by Jim Veatch in his award-winning RF amplifier designs. Applications For Baby-QRO applications, we can use Wurth 744851330 coupled inductor. For 5W / 10W RF amplifier applications, we can use Bourns SRF1260A-4R7Y coupled inductor. Recently we were able to utilize very cost-effective YJYCOIN YPRH1207C-4R7M Chinese coupled inductor with excellent results. With our current Digital Amplifier designs, this Chinese coupled inductor works even at ~75 MHz. ...
Our 6m WSPR beacon design works fine now. The key is to use a 25 MHz high-quality TCXO, like the 25 MHz HCI 0.5ppm TCXO! 2m WSPR is still out of reach for this VFO design - see the following drifty screenshots: While WSPR is no good, 2m FT8 works pretty fine! ...
We make heavy use of Easy-Digital-Beacons-v1 for testing RF amplifiers. This single board is a versatile WiFi VFO and FT8 / FT4 / WSPR beacon. You can also use our CW-SigGen project to generate a suitable test signal.
Tokmas CID9N65E3 rocks! Performance It is CRAZY how efficient this GaN FET is in TO-252 (DPAK) package. It generates 5W @ 28 MHz with 13.8V at drain without even warming up! Close to 4W @ 50 MHz with 12.0V at drain. 5W+ @ 50 MHz with 13.8V at drain. 11W+ @ 50 MHz with 20V at drain. It even produces ~3W at 70 MHz with 13V at drain - w00t! ...
I recently found some FET gate drivers which are quite fast! The Drivers Wuxi Maxinmicro MX1025D - Favorite! BD2311NVX-LBE2 from ROHM Semiconductor TI LMG1020 Tokmas LMG1020YFFR Usage They are perfect for driving the fast Tokmas GaN FETs that we recently discussed on this site. Our 'workhorse' gate driver for the recent experiments has been the Onsemi's NCP81074ADR2G in a friendly SOIC-8 package. And we have shifted to MX1025D gate driver in our latest amplifier designs. ...
I am posting an early design sketch of a 2m 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 might work @ 144 MHz as the 'final'. If not, use Mitsubishi RD15HVF1-501 MOSFET as backup. 2SK3475 as the driver with variable DC bias at the gate The whole VCC to this amplifier will be PTT switched Ideally, we would want to keep the driver stage linear but the final stage as switched (Class C/D) Alternate: Perhaps by DC coupling the Si5351 input to 2SK3475, we can avoid the need for DC gate bias The "RFC" (bifilar coil still needed?) part will need to be figured out for VHF! Status Results: To be built and tested soon! ...
I am posting 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! ...
This ~1W to ~5W WSPR beacon runs continuously on the 10m band. It handles extreme environmental temperatures pretty well (it is 42°C plus here). Our article on this beacon's design and operation will appear in the May/June 2025 issue of the QEX magazine soon. References WSPR TX by G0UPL QEX May-June 2025 TOC ...
Ismo (OH2FTG) recently introduced me to a bunch of Tokmas RF parts. Out of these, the Tokmas CID10N65F GaN FET stood out. It seems to have a lot of potential (for HF + 6m) at a very low price point. This RF MOSFET part can be purchased from LCSC. It seems Tokmas CID10N65F has the potential to completely replace the RD16HHF1 part from Mitsubishi Electric! Datasheet Datasheet excerpt: ...