Re: 24 volt
Found the reference.... WA2EBY. Take a look at:
http://www.golddredgervideo.com/kc0wox/wa2ebyamp/ (pointer to availability of boards) and http://diycrap.blogspot.com/2016/06/wa2eby-irf510-amplifier.html and http://kit-projects.com/AMP.en-us.htm
Although I am already committed to the ebay cheap amp, (nice construction with pointers to heat sync etc. at http://pa-11019.blogspot.com/2016/11/diy-kits-70w-ssb-linear-hf-power.html. ) certainly tempted to look at. WA2EBY...