Don, > The manual suggests that you calibrate the S-meter with the preamp ON. > If you do that, and set the S-meter to ABS, you will find that the > S-meter response is about 2 S-units lower than what you may expect.
Interesting. I assumed that in ABS mode it didn't matter if the preamp was on or not. I sheepishly admit I have never bothered to calibrate my K3 S meter. No excuse - I have an HP8656B signal generator sitting right next to the K3 - I just never got around to it. I'd do it right now but it's time to go to bed. :=) > The K3 has re-vitalized the old Collins 50 > uV equal S-9 "standard". That standard is not a standard at all, Actually IARU Region 1 has published Technical Recommendation R.1 which specifies S9 = -73 dBm (50 uV into 50 ohms) and 6 dB per S-unit. http://en.wikipedia.org/wiki/S_meter#IARU_Region_1_Technical_Recommendation_R.1 But you're right, that recommendation is more honored in the breach than the observance. (Gosh, quoting Shakespeare on the reflector - what are we coming to? :=) Alan N1AL On Sun, 2011-01-16 at 00:43 -0500, Don Wilhelm wrote: > Alan, > > I might add about the K3 CONFIG: SMTR MD = ABS, that the calibration > procedure indicated in the manual may (or may not) be the "proper" thing > to do. > The manual suggests that you calibrate the S-meter with the preamp ON. > If you do that, and set the S-meter to ABS, you will find that the > S-meter response is about 2 S-units lower than what you may expect. I > prefer to do the calibration with the S-meter off, and then the response > in SMTR ABS is more what I would expect. > > Since everyone's expectations do not necessarily match mine (obviously, > I disagree with Wayne on this item), you can take your pick - do it the > way the manual says, or do it like I have. The choice is entirely > yours. Like all things S-meter reading related, there is a great > variation between receivers, The K3 has re-vitalized the old Collins 50 > uV equal S-9 "standard". That standard is not a standard at all, and > many transceivers do it differently, but with the K3, you do have a > choice depending on how you want to set it up. If you cannot decide how > you want it, go with the manual instructions - they work and work quite > well. If you deviate, know why you are doing that deviation and know it > is for your own situation, others may or may not make the same choices. > > 73, > Don W3FPR > > On 1/16/2011 12:20 AM, Alan Bloom wrote: > > There are a couple reasons why the K3's S meter and the P3 display may > > show a different level. > > > > As Don mentioned, the P3 will generally show a much lower level than the > > K3 on noise. It's because the effective bandwidth of the P3 is > > generally only one display pixel, about 1/450 of the span. Less > > bandwidth means less noise power in each display point. The same thing > > happens to some extent with an SSB signal. > > > > Another issue is that the S meter reading on the K3 may change when you > > turn the preamp or attenuator on or off. To prevent that happening, set > > CONFIG:SMTR MD to "ABS". > > > > If you do that and calibrate both the K3 S meter and the P3 amplitude, > > then the two should closely agree when measuring a steady CW carrier. > > > > Alan N1AL > > ______________________________________________________________ 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
