Jeff, I would consider an ohm meter reading of a non-inductive resistor to be a better indicator of low SWR than any available SWR meter including the famous Bird (available since about 1940 or before). My MFJ-989C tuner includes a dummy load rated at 300 watts. It appears identical to the 50 ohm resistor in my 35 year old Heath Cantenna but without the can of cooling oil. I also have a 15 watt dummy load that I bought from Radio Shack about 20 years ago that measures 50 or 51 ohms. I would consider any of these good enough to calibrate a watt meter or an SWR meter. Rectifying and measuring the RF voltage will probably induce more error than the resistor. Willis 'Cookie' Cooke K5EWJ
________________________________ From: "Jeff Hall, W6EZY" <w6...@arrl.net> To: elecraft@mailman.qth.net Sent: Tue, February 23, 2010 12:13:39 PM Subject: [Elecraft] Need to select a dummy load for K3 TX calibration...(advice?) Hello all, I need help picking out a proper dummy load to use for calibrating my new K3. HRO is just up the road and they carry some of the less expensive MFJ dummy loads -- would these be sufficient? Not looking to spend a lot of money, but don't want to buy junk either. What factors should I consider? I'm assuming oil-cooled dummy loads are more robust, while air-cooled loads are more compact, but you have to be more careful when operating or they can burn up more easily. The K3 manual says this is just a 5W test and I need a load with low VSWR from 160 to 6. What is considered "low" SWR? Anything under 1:5? If I can get by with the MFJ-260 for just $40, that sounds reasonable to me. 73 de Jeff, W6EZY ______________________________________________________________ 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 ______________________________________________________________ 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
