The secret to using wire-wound resistors for a 50Ω load is to use a lot of them in parallel as the inductance divides just as the value does for the number of resistors. Of course, this is only reasonable if you already have a pawful to start with. Otherwise, RF rated, big 50Ω non-inductive resistors are available from many sources. I had a lot of 1200 Ω, 10 watt (light blue??) wire-wound resistors, so 24 of them between two pieces of G-10 made a decent HF dummy load with a good safety factor at 100 watts.
Another handy load, is one that will show 2:1 (100Ω) or 3:1 (150Ω) SWR. It wouldn't have to take much power as you'd only be using it to check an SWR readout, etc. I made a few out of a couple 2W resistors. They'll take reasonable power for a very short (½ second??) check time. 73, Charlie k3ICH -----Original Message----- From: [email protected] <[email protected]> On Behalf Of CUTTER DAVID via Elecraft Sent: Tuesday, July 23, 2019 6:44 AM To: hawley, charles j jr <[email protected]>; Art Nienhouse <[email protected]> Cc: [email protected] Subject: Re: [Elecraft] Dummy Load recommendation) I often wonder just how useful a precision dummy load really is in the amateur service. I picked up home brew dummy load at the club the other day. It measured 57ohms dc and comprises 4 wire-wound resistors attached in a cluster across the end of the coax. After lots of disparaging remarks I put it on the VNA and it didn't look at all bad out to 30MHz: nothing over 1.5:1 and no spikes or dips to indicate resonances. I'll have to do it again and make a print-out for posterity. I've heard that salt water in a bucket works after a fashion. So the question is: how good do you need it to be? David G3UNA ______________________________________________________________ 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]
