To follow up on Victor's point, did some more measurements this morning. Setup: KX-3 minimal adapters to 40 dB directional coupler to load terminated unused port of coupler measured port through 3 ft patch to Kanga US AD8307 RF power meter
I have good calibration data for the power meter, but for the purpose at hand, I won't correct the meter readings. 60 on the scale is about -20 dBm. Every 10 on the scale is actually 10.7 dB. Good enough. Internal tuner bypassed. Measurements: Note: RX current in RX was between about .15 and .19 A for all 3 bands. 14 MHz @ 1 W setting 13.7 V RX (per KX3) 13.4 V TX (per KX3) 1.15 A TX (per KX3) VSWR 1.3 (per KX3) FWD 67 (on power meter display, very close to expected) REV 30 (on power meter display) --> return loss approx 37 dB 28 MHz @ 1 W setting 13.7 V RX 13.4 V TX 1.15 A TX 1.3 VSWR FWD 67 REV 30 --> return loss approx 37 dB 50 MHz @ 1 W setting 13.7 V RX 12.9 V TX 2.9 A TX 1.6 VSWR FWD 71 REV 35 --> return loss approx 36 dB Hmm. So, I'm seeing 3% or less efficiency. Only one respondent on my query about TX current draw, and he was getting 15%+ efficiency. No wonder my PA temp shoots up. Thanks, Drew n7da On Sat, May 9, 2020 at 11:25 AM Drew Arnett <arnett.d...@gmail.com> wrote: > > Good point, Victor. And why I included that SWR reading. Other bands > read fine. I have high confidence in the load and adapter (tried > swapping both just in case). I could measure the load and adapter the > next time I'm in the lab at work if I want to be absolutely thorough, > but it is a microwave load and just adapting from BNC to N (no coax). > > SWR looks fine on other bands. > > Thanks, > > Drew > n7da > > On Sat, May 9, 2020 at 4:57 AM Victor Rosenthal <k2vco....@gmail.com> wrote: > > > > I think 1.6:1 is high for that kind of dummy load, if it's in good shape. > > Should be close to 1:1. > > Anyway, you can't really say there is a problem unless you have a better > > match. Current draw is sensitive to mismatch. > > -- > > Vic > > > > On May 9, 2020 2:32:15 AM GMT+03:00, Drew Arnett <arnett.d...@gmail.com> > > wrote: > >> > >> Walter, > >> > >> 50 MHz TX constant 4 W carrier measures 13.53 V on DMM (outside the DC > >> power plug), 13.3 V on KX3 meter, 2.9 A on KX3 meter and 1.6 to 1 VSWR > >> on KX3 meter. Microwave dummy load with BNC to N adapter. > >> > >> I didn't measure all of this when the rig was new, so have no baseline > >> to know what is normal. :-( > >> > >> Thanks, > >> > >> Drew > >> n7da > >> > >> On Fri, May 8, 2020 at 11:19 PM Drew Arnett <arnett.d...@gmail.com> wrote: > >>> > >>> > >>> What do you see for current draw on the KX-3? Manual says 1 to 2 A > >>> typical. > >>> > >>> I'm seeing 3 A at less than full power on one band. Yikes! Makes me > >>> wonder if the repair shop is open? Elecraft website says hunkered > >>> down and mostly work from home. > >>> > >>> Thanks and best regards, > >>> > >>> Drew > >>> n7da > >> > >> ________________________________ > >> 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 > >> Message delivered to k2vco....@gmail.com ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
