Vin, What you are observing at the low end is differences in the diode characteristics. The WM-2 has a diode compensation circuit which attempt to correct the readings at low power levels while the KAT1 does not - so the WM-2 is likely more correct at the low end
The difference at the high end does not have such a straightforward and easy answer. You might look into your dummy load, the length of coax between the KAT1 and the WM-2 and various other factors for the answer. Try another band, you could find the difference is frequency dependent too. If you have a good 50 ohm non-reactive dummy load (check it with an antenna analyzer to be certain), you can read the RF voltage across the dummy load with a calibrated 'scope or an RF probe and calculate the power. This method is quite accurate (better than most wattmeters), but is highly dependent on the accuracy of the dummy load. BTW - I do not perceive anything really bad here - just inaccuracies. Equate that to the man with two watches - he never knew what time it was <G>. 73, Don W3FPR > -----Original Message----- > > I have been enjoying my K1-4 immensely for many months now, and > am getting ready to build the KAT-1. But I decided to build my > OHR WM-2 first, so as to get a good idea of how the antenna tuner > is actually performing. Well, the meter went together on a > Sunday afternoon/evening very nicely, but there is one thing I noticed. > > My K1 goes from 100 mW to about 7.1 W according to the front > panel display (of the K1). Now, when I look at the power out on > the meter, I see good agreement with that from around say 2 watts > to about 5 watts. But at the low and high end, the meter reads > high. Approximately 300 mW when the radio says 100 mW, and about > 6 watts when the radio says 5 watts. At the top end, the > difference is even a little worse, approx 8.5 watts on the WM-2 > when the K1 says 7 watts. > > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
