Not finding any recent posts at all about the HF Packer Amp, I’ll take a chance with this post. My apologies if this is old news to the SOTA world.
Virgil, K5OOR at HF Projects has recently started shipping a new version of the HF Packer Amp kit, dubbed the “miniHFPA”. Virgil designed the miniHFPA to target the SOTA/NPOTA crowd, so it is very small, requires so little as 1 watt drive for full output (nominally 35 watts), barely sips current when idling, and will maintain full output even when battery voltage falls to 10 VDC.
Early builders are reporting output levels somewhat higher than 35 watts on the lower bands, which is good news considering the propagation outlook for the next few years.