Tim Duffy, K3LR has built one of the leading contest stations that holds many contest records. He joins Bob Heil on HAM NATION Wednesday 23, 2018 at 8:00 PM CST. You will not want to miss Tim's demonstration of RFI and how to eliminate it.
Several years ago, Jim Brown (K9YC') literally wrote the book about how to solve RFI: http://www.audiosystemsgroup.com/RFI-Ham.pdf His latest composition has some updates that includes info about new ferrites: http://k9yc.com/GroundingAndAudio.pdf Jim is a frequent contributor on the very active TowerTalk email reflector: http://www.contesting.com/FAQ/towertalk
Jim has a nice presentation. If you have a hard time falling asleep here is the commercial version: http://www.ronet.co.za/downloads/R56 Guidelines.pdf
From Jim yesterday: After nearly a year of work, I published a new "cookbook" last month. For reasons that are detailed in the accompanying text, I no longer recommend coax wound through multiple cores. The short answer for "why not?" is that it's simply not practical to wind chokes that way and get anything close to the same result every time -- turns must go through the core in the same order, a scrambled turn cancels a turn, turn diameter matters a lot, and so on. The new cookbook uses RG400, 12-2 Teflon/silver pairs, or 12/2 THHN or NM pairs, all tightly wound around a single core. There are recommendations for chokes in series to increase power handling. There is also data for the new 4-in o.d. supersized toroids, which are great for 160M. k9yc.com/2018Cookbook.pdf 73, Jim K9YC Ive followed Jims work for many years and find him far above other sources for the quality of his work. Carl
