No problem. Yes, open wire line has its own problems. I was reacting to your note regarding using short runs of coax operated at high SWR. There is nothing inherently inefficient about doing so. Like any design it’s easy to run the numbers to determine what the actual losses are. Many times they are just too small to worry about. Especially in the case of verticals, the ground losses will be far higher unless you invest in an excellent radial/ground shield underneath it. The tuner can’t help that.
Ken K6MR From: James Rodenkirch<mailto:[email protected]> Sent: Wednesday, April 27, 2016 11:01 To: Ken K6MR<mailto:[email protected]>; [email protected]<mailto:[email protected]> Subject: Re: [Elecraft] Sherwood's receiver performance table updated Did not mean to sound argumentative, Ken.....apologize if it came out that way....I am "involved" in this discussion becuz' of Don's initial post about new hams not understanding the advantageous aspects of open wire feed line.... ________________________________ From: James Rodenkirch Sent: Wednesday, April 27, 2016 10:38 AM To: Ken K6MR; [email protected] Subject: Re: [Elecraft] Sherwood's receiver performance table updated It is not "the principle behind the use of open wire feed line," Ken IF, I place an antenna auto tuner at the base of, for instance, a vertical and feed the tuner with low loss coax.... I understand the use of open wire feed line and an ATU prior to attaching to the xmtr....BUT...see above - works as well, if not better 'cuz I don't have to worry about the open wire feed line running too close to metal objects... ________________________________ From: Ken K6MR <[email protected]> Sent: Wednesday, April 27, 2016 9:36 AM To: Jim Rodenkirch; [email protected] Subject: RE: [Elecraft] Sherwood's receiver performance table updated "P.S. I don't subscribe to the notion that quality coax runs of < 150 feet make it "ok" to have the ATU in the shack while operating an antenna on multiple bands....what technical evidence of that posit do you have to share????" Jim: Google "transmission line bounce diagram". This is a simple concept easily proven by mathematics. On a practical level, this is the concept behind the use of open wire feed lines. It's been done for decades. The type of feed line does not change the theory. Ken K6MR From: Jim Rodenkirch<mailto:[email protected]> Sent: Wednesday, April 27, 2016 06:21 To: [email protected]<mailto:[email protected]> Subject: Re: [Elecraft] Sherwood's receiver performance table updated "It all depends" is/was the premise for my reply, Don. If new and old hams don't understand the potential problems with long runs of coax to/from an antenna they want to operate on multiple bands and an ATU in the shack they will be surprised at how inefficient their system is. P.S. I don't subscribe to the notion that quality coax runs of < 150 feet make it "ok" to have the ATU in the shack while operating an antenna on multiple bands....what technical evidence of that posit do you have to share???? Note 1: I had a 43' vertical with top loading wires in a NORD-style config with my external ATU at the base of the vertical and 120' of coax back to the shack ---- never saw a VSWR delta of more than .2 between what was "seen" at the input to the tuner and what was "seen" at the xmtr while operating on 160 through 20 meters. -- View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-s-receiver-performance-table-updated-tp7616652p7616802.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
