Notes on coupled inductors

The usage of ready-made coupled inductors in RF designs was pioneered by Jim Veatch in his award-winning RF amplifier designs.

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.

References:

• https://github.com/kholia/HF-PA-v10/tree/master/GSD-Hacks-v5

• https://www.lcsc.com/product-image/C22387935.html

• See https://www.lcsc.com/search?q=YPRH1207C for the full range

• Also see https://www.lcsc.com/search?q=XRRF7342 (only 7.5x7.5)