Joe, Comparing the K3 S-meter with the P3 amplitude indication has some limitations.
You stated that your K3 has been calibrated with the XG2 and I have no reason to doubt that, but do realize the granularity in that calibration. If you calibrate the K3 S-9 indicator bar to just barely come on at -73 dBm, and it will be the only bar illuminated until the signal goes up to -67 dBm (assuming 6 dB per S-unit). So your indication is well within that granular step. OTOH, if you calibrated the K3 S-meter so the S-9 indication is on full at -73 dBm, then your K3's S-9 could be as low as -79 dBm. When comparing the K3 S-meter reading to the P3, one must consider this granularity in the K3 S-meter - in other words, it is not an "exact science" - allow for a +/- 6 dB range when making comparisons unless you have calibrated the K3 S-meter with this granularity in mind and can define the S-9 range more closely with accuracy. I believe Alan is working on additional calibration processes for the P3, so if we could give this subject a bit of a rest until he completes that work, we will keep the reflector more quiet for now - after the P3 calibrations are in place, then I am certain comments on accuracies and inaccuracies of the response will be well received and appreciated. What we have currently is a digital display with its digital granularity being compared to an analog display with greater resolution than the digital display - to me, that is like comparing apples and oranges unless the granularity (and its consequences) is understood. Those of us old-timers who grew up in the analog meter world do have a difficult time with this fact - it just does not seem "natural" unless we have gone through the "digital indoctrination" and learned its consequences. 73, Don W3FPR On 9/27/2010 5:26 PM, Joe Subich, W4TV wrote: > > > I've had several replies, all report the XG-2's -73dBm level to be > > between about -78dBm and -80dBm on the P3, so it's at least > > consistent, and will, no doubt receive Elecraft's attention in > > due course! > > Well, my XG-2 shows up at -68 to -70 dBm on my P3. The P3 shows > a no signal noise floor of -150dBm (RX Ant) in a 2 KHz span. The > K3 has been calibrated to this same XG-2 using the K3 Utility and > reads S9. The 1 uV output shows up at -105dBm with the same test > conditions. > > The K3 has the IF output modification fitted. > > 73, > > ... Joe, W4TV > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
