I just looked it up. The XG2 has a specified level accuracy of 2 dB, and 1 dB typical. A professional lab-quality RF signal generator would typically be about twice that good (hard spec in the 1 dB range):
http://www.home.agilent.com/agilent/redirector.jspx?action=ref&cname=AGILENT_EDITORIAL&ckey=843957&lc=eng&cc=US&nfr=-536906709.536910813.00 So if you have access to a calibrated lab-quality signal generator, then use it. But the XG2 isn't bad and is about 100 times cheaper. :=) Alan N1AL On Sat, 2010-09-04 at 11:55 -0700, Phil Hystad wrote: > Alan, > > Thanks for the excellent answers. So, if you created a signal level > calibration > would the Elecraft XG2 be a bitting and accurate signal source? Or, would > some > lab equipment be needed. Actually, I don't really know how the XG2 compares > to some lab quality equipment, it may be just as accurate. > > PEH > > > On Sep 4, 2010, at 11:42 AM, Alan Bloom wrote: > > >> My first question is: what is a reasonable setting? > > > > It's kind of a "season to taste" -- whatever gives a pleasing display to > > your eyes. When the waterfall is turned on, I find that it's best to > > adjust the REF LVL so that the noise level is right at the bottom of the > > spectrum screen. That seems to make weak signals easiest to spot on the > > waterfall. > > > >> I am not quite sure how accurate this is. > > > > I would guess that typically it should be within a few dB. Let's say > > within one S-unit (6 dB). I plan to add a feature so you can calibrate > > it against an accurate signal source. > > > >> ...and noticed that this particular SSB signal on 17 meter band this > >> morning read peak about -100 dBm or about a 32 dBm strength over the > >> minimum reading on the scale. I would like to equate this to a rough idea > >> of an S meter reading. By my calculations, this should be a little bit > >> above an S4 reading. Can someone confirm that I am in the right ball park? > > > > What I do is to remember that S9 is -73 dBm (an easy number for a ham to > > remember) and there's 6 dB per S-unit. So -100 dBm is (100-73)/6 = 4.5 > > S-units below S9. So between S4 and S5. > > > > Another item on my "to-do" list is a MENU option to change the scale > > from dBm to S-units and dB over S9. It's not all that hard to do, I > > just need to clear some higher-priority tasks off the list first. > > > > Alan N1AL > > > > > > On Sat, 2010-09-04 at 09:12 -0700, Phil Hystad wrote: > >> I am trying to get a better understanding of the P3 signal level scale > >> (left vertical scale) with respect to absolute signal levels and the S > >> meter readings. > >> > >> I have my REF LVL set to -132 dBm. My first question is: what is a > >> reasonable setting? I merely am guessing at the value of -132 dBm and > >> also I am not quite sure how accurate this is. According to the P3 > >> manual, this is essentially the signal strength at the antenna terminal of > >> my K3 (taking into account the pre amplifier which I happen to have Off). > >> > >> Also, I was monitoring a signal using the PEAK reading capability of the > >> P3 and noticed that this particular SSB signal on 17 meter band this > >> morning read peak about -100 dBm or about a 32 dBm strength over the > >> minimum reading on the scale. I would like to equate this to a rough idea > >> of an S meter reading. By my calculations, this should be a little bit > >> above an S4 reading. Can someone confirm that I am in the right ball park? > >> > >> Thanks for the help. > >> 73, phil, K7PEH > >> > >> ______________________________________________________________ > >> 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 > > > > ______________________________________________________________ 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
