Jim, Indeed, and an observation I too had made (you'll note I didn't say it's 'in service', merely 'given to me').
I was just trying to provide an illustration of what was being described by Dale. John (XLX) -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim Brown Sent: 01 January 2017 19:32 To: elecraft@mailman.qth.net Subject: Re: [Elecraft] {OT} - Variation on use of a coaxial switch (stan levandowski) The isolation provided by this switch will be really poor. In addition to the capacitive coupling of the switch itself, note that only the center conductor is carried between inputs and outputs, so that the chassis carries return current. This adds a lot of inductance to the path, and causes crosstalk between circuits. The RIGHT way to do this is to provide a coaxial path, so that return current is confined to the coax shields. If you look inside the Alpha Delta switches you see that they are built that way. There's not coax cable between in and outs, but the physical construction is such that the body of the switch forms the return path. Not perfect, but FAR better. 73, Jim K9YC On Sun,1/1/2017 10:37 AM, John wrote: > What Dale describes below is a very similar configuration to the MFJ > switch I was given a year or so ago - an MFJ-1703. > > I just popped the lid off and took a photo of the insides for you: > > https://www.dropbox.com/s/h28jny6vrkj7rdj/2017-01-01%2018.28.00.jpg?dl > =0 > > The only difference being that it's basically a DPDT slide switch, > rather than a rotary. Works just as well. > > At least, I think that's pretty much what he was describing anyway. > Stick a dummy load on one output and your antenna on the other, and > your two rigs on the two inputs. > > 73, and a firm left handshake, > John (XLX) > > -----Original Message----- > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of > Dale Martin > Sent: 01 January 2017 17:31 > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] {OT} - Variation on use of a coaxial switch > (stan > levandowski) > > Stan, > I haven't taken the time to read all the other responses, but have you > considered building your own coax switch. > > Parts: 1 aluminum box, 4 SO-239's, 1 two-pole, multi-position rotary > switch (you only need 2 positions, but more is okay), 100w dummy load > > Mount the SO-239's (J1-J4) and rotary switch > > Wire up the switch thusly: > Pole 1 to J1 (KX2) > Contact 1 to J3 (antenna feedline) > Contact 2 to J4 (dummy load) > Pole 2 to J2 (KX1) > Contact 1 to J4 (dummy load) > Contact 2 to J3 (Antenna feedline) > > When you switch one radio the antenna, the other radio is then put on > the dummy load. > > 73, > Dale, kg5u > > >> ------------------------------ >> >> Message: 3 >> Date: Fri, 30 Dec 2016 17:49:21 -0500 (EST) >> From: stan levandowski <sjl...@optonline.net> >> To: Elecraft@mailman.qth.net >> Subject: [Elecraft] {OT} - Variation on use of a coaxial switch >> Message-ID: <1d09982f.1e408.15951ec5b8d.webtop...@optonline.net> >> Content-Type: text/plain; charset=UTF-8; format=flowed >> >> I would like to use a coaxial switch for an unintended use and I'm >> not > sure if >> it's a good idea in terms of RF isolation and potential equipment damage. >> >> I'm no expert in this area but I know this list is a wealth of expert > opinion, so >> here's my question: >> >> >> I want to buy a two position coaxial switch. ?I want to connect ONE >> antenna to it and switch this antenna between a KX2/KXPA100 (100 >> watts) and a KX1 (about 3 watts). ?The coax cable coming from this >> switch to the KX2 is a short piece of RG8X and the coax cable going >> from this switch to the KX1 is 25' of RG-174 (yes, I already computed >> the dB loss and I can live with).? >> >> >> Am I likely to cause any damage to to either piece of equipment? >> >> >> Thanks, >> Stan WB2LQF > ************************************* > > ______________________________________________________________ > 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 Message delivered to > j...@eeek.org.uk > > ______________________________________________________________ > 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 Message delivered to > j...@audiosystemsgroup.com > ______________________________________________________________ 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 Message delivered to j...@eeek.org.uk ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
