John, IMHO, believe the DL-1/DMM combination first. If you have an opportunity, check the DL-1 with an antenna analyzer to see how close it actually is to 50 ohms non-reactive - that should increase your confidence level.
The WM-2 when properly calibrated is speced for 5% of full scale, so if you were reading on the 10 watt scale, its reading could be off by as much as 0.5 watt, if not calibrated, it could be off even more. I find my W7EL wattmeter (predecessor to the WM-2) is optimistic in its readings (reads high) even when calibrated by the 'proper' instructions - one day I will do a better job of matching the diodes and straighten it out, but in the meantime I trust my known 50 ohm non-reactive dummy load and my 'scope or RF probe a lot more. 73, Don W3FPR > -----Original Message----- > > Just finished building KX-1 #1207 with 30m board and ATU. Nice > little rig! > > After adjusting C9 on the KXAT-1 per the manual, I decided to compare the > power output measurements obtained via the internal power sensor, a DL-1 > dummy load + DMM, and using my OHR WM-2 QRP wattmeter. BTW, the supply > voltage is 12.5v and I substituted a 33-ohm resistor for R30. > Output before > I changed R30 was about 1-watt lower across the board. Here are > the final > measurements, as built: > > Band DL-1+DMM Internal WM-2 > 20m 2.6 3 3.7 > 30m 3.7 4 4.7 > 40m 3.4 4.1 4.3 > > Which wattmeter should I believe? I tend to think the DL-1 plus my Fluke > digital multimeter would give me the most accurate reading, but.... > > -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.9.0/50 - Release Date: 7/16/2005 _______________________________________________ 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
