I am putting together a portable station using my Flex 1500. I decided that I can probably get away with a wall-wart supply instead of carrying around the 25A supply I use for the 3000. I am also thinking about a reasonable size (and price) for a LiFePO4 (Lithium-Iron-Phosphate) battery pack to run things. (LiFePO4 is lighter and easier to charge than NiMH and WAAAY lighter than sealed lead-acid.) To this end I need to figure out what the drain of the 1500 is in both RX and TX at full power. I have a power-measuring device that can be put in the power feed that measures both voltage and current, and then calculates and displays volts, amps, watts, watt-hours, and amp-hours. These devices seem to be pretty common as they were developed for RC modelers to calculate battery pack needs and battery pack health.
But I ran into a bit of a problem. I noticed that I was getting strange and sometimes low readings that didn't make sense, i.e. the radio drawing only 5W from the supply when it was producing 4W of RF output. 80% efficiency of a linear class-AB PA is *very* unlikely. Then I noticed that the values changed when I disconnected the external reference. I discovered that the watt-hour meter measures current in the negative/ground lead and not the positive/power-in lead. Multiple ground paths were causing errors. If you have one of these devices it is important to determine whether the current shunt is in the positive or negative lead or it will provide incorrect readings. FWIW, my 1500 draws 300mA on RX and 1250 mA on TX at full 5W output. -- Brian Lloyd, WB6RQN/J79BPL 3191 Western Dr. Cameron Park, CA 95682 [email protected] +1.767.617.1365 (Dominica) +1.931.492.6776 (USA) (+1.931.4.WB6RQN) _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software.
