Re: Inexpensive eBay Amplifier Kits
Paul Galburt - K2AYZ
I recently bought one on AliExpress.
This one features a built-in LPF, which seems unusual - but really convenient. The provided LPF is for 13.56 MHz, but retuning for a ham band seems fairly simple. I have not had time yet to built this kit, but I have contacted the maker a couple of times and they seem responsive.
That said, I think getting them to provide a different filter will be a long, drawn out process, and not in keeping with a $20 kit. The 13.56 MHz filter is not far from what's needed for 40, 30, or 20 meters, so the provided toroids could likely be used.