On 26 Jan 2018 at 18:19, D.J.J. Ring, Jr. wrote: > ...old school vacuum power FETs with the internal pilot lights Also known by some as "thermatrons", and by others as "hollow-state FETs". Ken W7EKB --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus