> Running a heavy power supply line with a lighter gauge wire at > the radio end OR a lighter wire at the power supply end, the > overall net supply resistance (and voltage drop) will be the same. > For example, 100 Ohms in series with 1 Ohm equals 101 Ohms net total > resistance.
Use *realistic* resistance values. For example, a 10 foot piece of of #8 wire (0.63 milli-Ohms per foot) with a six inch "pigtail" of #12 wire (1.5 milli-Ohms per foot) is equivalent to 11' 3" of #8 wire or less than one foot of #12 wire. The *contact resistance* in a 15A Power Pole (0.88 milli-Ohms) is, *by itself,* is equivalent to more than six inches of #12 wire. Ohm's Law is *exactly* why we would all be better off if the power jack on the K3/K3S was doubled up and the power cable replaced with #6 or #8 wire even if it were necessary to splice in some 4" pieces of #10 or #12 wire to mate with the 15A Power Pole connectors. #10 or 1/4" bolts for the power terminal with #8 wire and ring terminals on both ends would reduce the voltage drop in the power cable by 75%, if the bolted connections were torqued properly, compared to #12 wire and 15A Power Pole connectors. 73, ... Joe, W4TV On 2018-04-12 11:19 AM, James Wilson wrote:
Buck, Running a heavy power supply line with a lighter gauge wire at the radio end OR a lighter wire at the power supply end, the overall net supply resistance (and voltage drop) will be the same. For example, 100 Ohms in series with 1 Ohm equals 101 Ohms net total resistance. Likewise 1 Ohm in series with 100 Ohms is still 101 Ohms. It doesn't matter if you take the voltage drop at the input or at the output end of the power run if the total load is at the end of the run. I checked with Dr. Ohm to verify this. :-) Jim - W4RKS ______________________________________________________________ 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]
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