Link to K2AV Web site https://k2av.com/
Original pdf.
https://www.okdxf.eu/files/Olinger_FCP_article_as_published_in_NCJ.pdf
Link to BalunDesigns FCP transformer: http://www.balundesigns.com/1-1-fcp-isolation-transformer-2kw-1142s/
Great article from W0UCE https://web.archive.org/web/20160316210818/http://www.w0uce.net/K2AVantennas.html
An article by W4KAZ: http://w4kaz.com/qth/?p=2066
Another good article: http://www.dm9ee.de/FCP_info.html