Interesting. I worked at the Cam Rahn Bay comm center during all of 1968 and never heard of this. All the encrypted traffic for the command passed through us.
I also worked the Comm Center at Cam Rahn from Setp to Dec .67. Send me an email at harry_brewer@hotmail.com. I’ve been absorbed by this story too and just finished “One Day Too Long”. Harry Brewer, SP5, US Army ‘65-’70, RVN 9/67-9/68,