Rick, K7MW asked: With my K2 into a DL1, my WM-2 meter shows up to 20 % higher power than my DMM and slide rule indicates. Is the DL1 likely more accurate than my WM-2 meter. If so, I will recalibrate my K2 with the DL1 and DDM. Than I will have a stronger QRP signal and be able to work 300 new countries. I could also recalibrate my WM-2. Also, I wonder if the K2 maximum output power is increased if the voltage goes up. Just in case I need to cheat a little with QRO power (15watts or so). But I promise not to get an amplifyer..
---------------------------------- At decent power levels (several watts), diode detector with a capacitor across the output to the DMM (to charge up and show peak voltage) is the most accurate wattmeter most hams can get. The accuracy is limited solely by the accuracy of the DMM and accuracy of the value of the resistive load on the RF source. Notice "resistive" in that statement. It's absolutely essential the AC (or RF) signal be looking into a non-reactive load. So go for it, and rack up those new countries!! All QRPers know that milliwatts are important. But you make an excellent point. A few milliwatts (or even watts) makes very little difference on the air in a given contact. The real thing to look at in comparing on-air performance is dB. We can hear a 6 dB difference pretty clearly, if we're listening for it. That's about 1 S-unit on most receivers. Although 1 dB is defined as that minimum change just perceptible in human hearing, most communications engineers consider 3 dB to be about the minimum discernable change in radio communications in the most ideal conditions. That's why twice that - 6 dB - is commonly consider an "S-Unit". It's just enough change to say the signal got stronger or weaker in most situations. I consider 6 dB to be about the minimum amount of change worth pursuing if I'm thinking of changing my power levels. Going from 15 watts with a QRP K2 to 100 watts with my K2/100 increased my signal by just over 8 dB. That's enough to be noticed. Going from 100 watts to 800 watts adds another 9 dB again. Again enough to be noticed. But I'd never spend a moment worrying about whether anyone can hear the difference between, say, 15 watts and 10 watts or between 100 watts and 50 watts. It just isn't going to happen. It's worth chasing milliwatts when we're trying to assemble the most efficient station. They add up. But in practice, doubling or even tripling the power (or reducing it that much) simply isn't going to be noticed. Ron AC7AC _______________________________________________ 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
