Stan, please forgive my post. Not meant to criticize you. 73, Bill K9YEQ
-----Original Message----- From: Elecraft [mailto:[email protected]] On Behalf Of stan levandowski Sent: Sunday, January 1, 2017 5:01 PM To: [email protected] Subject: Re: [Elecraft] {OT} - Variation on use of a coaxial switch (stan levandowski) Gosh, everybody, I didn't mean to create any controversy. FYI, I already have a high quality (??) Alpha Delta switch where "...unused terminals are grounded" and that's what I'm going to use. I'll just have to be careful. I use my KX2/KXPA100 most of the time and that's the position the switch will be routinely be in. The other switch position will be connected to 50' of un-terminated coax. Every once in awhile I feel like operating my little KX1 a) while lying in bed, b) by a roaring fire in my fireplace while it's snowing, c) on my front porch on a summer night with a glass of iced tea and d) on the back deck while doing BBQ. The switch and the 50' of coax allow me to connect my KX1 to my SGC-231 and (amazingly!) there's enough RF to kick the coupler into action. It's nice to get out of the shack and operate simply once-in-awhile and a good doublet beats a piece of wire by a country mile. Thanks to all and Happy New Year. On Sun, Jan 01, 2017 at 04:49 PM, Bill Johnson wrote: > John, > That MFJ switch is also a good example of some poor construction which > some > of the MFJ equipment has/had. I have some MFJ-998 equipment which had > some > excellent construction. > 73, > Bill > K9YEQ > > -----Original Message----- > From: Elecraft [mailto:[email protected]] On Behalf Of > John > Sent: Sunday, January 1, 2017 1:41 PM > To: [email protected]; [email protected] > Subject: Re: [Elecraft] {OT} - Variation on use of a coaxial switch > (stan > levandowski) > > 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:[email protected]] On Behalf Of > Jim > Brown > Sent: 01 January 2017 19:32 > To: [email protected] > 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:[email protected]] On Behalf Of >> Dale Martin >> Sent: 01 January 2017 17:31 >> To: [email protected] >> 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 To: [email protected] >>> Subject: [Elecraft] {OT} - Variation on use of a coaxial switch >>> Message-ID: <[email protected]> >>> 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:[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] >> > > ______________________________________________________________ > 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] > ______________________________________________________________ > 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] ______________________________________________________________ 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]
