Hi Dale, You can't inject DC into a coax feedline that carries RF with a simple T coax connector.You have to use a bias T circuit as has been recently discussed. It sounds like you have some coax from the rig to I assume a balun of some sort that connects to you balanced line. You should be able to adapt the bias T concepts to send DC thru the coax from the rig end to just before the balun using a pair of bias Ts. Then use the bias T concept on the other side of the balun to send DC through the balanced feedlilne to just before the antenna, isolating the DC from the antenna and isolating the relay from the RF.
73 - Mike WA8BXN -------Original Message------- From: Dale Putnam Date: 2/11/2014 7:23:31 PM To: elecraft@mailman.qth.net Subject: [Elecraft] Balanced feedline - DC Isolator With a pair of KAT100s and a pair of K2s, I need to send 12v up the openline feeder to control a latching relay at the top of the tower. The easiest way would be to run the dc on the feedline.and it would be even easier.. if the isolator would stop the dc from continuing on through the antenna.. that is also a dc short, inone of its configurations. I can insert the dc in the shack.. with a coax "T"... but there isn't a coax place at the top of the tower.Thoughts or ideas? Have a great day, --... ...-- Dale - WC7S in Wy > Date: Tue, 11 Feb 2014 15:53:05 -0800 > From: johnbsa...@yahoo.com > To: elecraft@mailman.qth.net > Subject: [Elecraft] OT ... Coax DC Isolator > > Many, many thanks for the fine comments and suggestions. I am going with the MFJ-4712 which is the bias tee and the relay and switch...complete and ready-to-go. > > Thanks again & 73, > John > K5ENQ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
