OT: Relays for antenna switching
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OT: Relays for antenna switching
 
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Hello All,
I planning to put up a 20m switchable vertical yagi made up of 4 vertical elements, with a relay control box to switch the elements to be either the driven element or the reflector elements. Preferable the relays should be DPDT, although I can use SPDT relays if they're cheap enough. - What relays should I use (any specific recommendations?) , or what characteristics should I look for in relays. The relay control box will be mounted on the antenna, so it has to operate over a very wide range of temperatures (below 0 to over 100 degrees), and be controlled via 12VDC. - What should the relay contact rating be to use with my K2 at 100 watts? - Will there be a significant amount of loss if I use power relays for RF applications (which seem to be the only ones in the catalogs that probably have a sufficient contact rating)? - Are the relays used in the KAT100 appropriate for "external" use (they would be in mounted a sealed box)... and does anyone know what the KAT100 relays are? (I expect the Elecraft would prefer that I order them from some othe rsource so that they're not a parts supplier for non-Elecraft projects). Thanks. Bob W1SRB _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: OT: Relays for antenna switching
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Bob ...
I recently built an outside switching box for another antenna project. Not switched verticals like you will have, but a way of switching a multiband doublet from doublet to tophat vertical operation. Also at 100W power level, so I'm guessing that the possible maximum voltage and currents in my application will be, if anything, greater than yours. I used a Potter Brumfield DPDT relay. Rated at 20A current. It has worked great. 12V coil. Mouser PN is 655-KUHP-11DT1-12. One reason I picked it is the mechanical package. It has a built-in mounting flange that you can simply screw to your chassis or to the inside of your enclosure. Then all the contact terminals are exposed and accessible for soldering. If I were doing your project I would use this one again. About $14 in small quantities. 73 ... Craig AC0DS _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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RF relays that are to be outside especially should have dual contacts.
The problem you're trying to avoid is corrosion that the transmitter has no trouble punching through but the puny RX signal sees as high resistance. Result 30 db or more loss of signal but with a good xmit SWR. So used DPDT relays when you really need SPDT relays and 4PDT when you need DPDT relays. Parallel contacts to avoid above. Some commercial antenna switches have bifurcated contacts (two contacts for each arm) to avoid this. Also one more point the 60HZ or DC current rating does not apply to RF. At RF contacts have much less current handling capacity. 73 de Brian/K3KO
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RE: OT: Relays for antenna switching
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In reply to this post by Solosko, Robert B (Bob)
Thank you to everyone who replied - I received much very good advice
about how to determine the relay characteristics that I need, how to mount the relays and specific relay recommendations. Thanks again and 73, Bob W1SRB -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Solosko, Robert B (Bob) Sent: Tuesday, February 19, 2008 1:00 PM To: [hidden email] Subject: [Elecraft] OT: Relays for antenna switching Hello All, I planning to put up a 20m switchable vertical yagi made up of 4 vertical elements, with a relay control box to switch the elements to be either the driven element or the reflector elements. Preferable the relays should be DPDT, although I can use SPDT relays if they're cheap enough. - What relays should I use (any specific recommendations?) , or what characteristics should I look for in relays. The relay control box will be mounted on the antenna, so it has to operate over a very wide range of temperatures (below 0 to over 100 degrees), and be controlled via 12VDC. - What should the relay contact rating be to use with my K2 at 100 watts? - Will there be a significant amount of loss if I use power relays for RF applications (which seem to be the only ones in the catalogs that probably have a sufficient contact rating)? - Are the relays used in the KAT100 appropriate for "external" use (they would be in mounted a sealed box)... and does anyone know what the KAT100 relays are? (I expect the Elecraft would prefer that I order them from some othe rsource so that they're not a parts supplier for non-Elecraft projects). Thanks. Bob W1SRB _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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