Don, I notice that if I have the RF gain less than full CW the S Meter bars are progressively lit and it looks like the noise level has increased when it has not. The latest beta is a work of art and should make folks happy but the S Meter / RF gain interaction puzzles me. Out of habit I do not run RF gain full out, but for a more accurate meter I guess I will. Can you explain the interaction?
Dan AB3EN Don Rasmussen wrote: > > Here's my look for what its worth. ;-) > > I have been following AGC, S-meter, and threshold/slope values since the > beginning - K2 #272 over two years ago. > > Until recently, I have found that K3 sensitivity varied between serial > numbers and that could not be changed. I suspect this value was not > measured before units left the factory. I had about 10db difference > between K3 #272 and #2308. > > The s-meter presentation was tied to that difference. A hotter receiver > would have a higher resting value on a given band that the more moderate > receiver. > > Happily, in the newest limited beta release this has been addressed. The > RF Gain can be calibrated to the user's satisfaction. It works great. For > example - tonight on 40m I see the same resting band noise that I'd see on > IC756p, or OMNI VI+. It is S3. > > In the past, the K3 always showed at least 2 points higher, sometimes 3, > assuming identical sensitivity with my other sets. So, in the past my K3 > would be showing S6 as resting. That was troublesome because I could not > see how strong anyone was, if it were less than S6. > > At my location the single biggest plus with my K3's was getting the > updated DSP board. That took all the critical adjustment out of THRESHOLD > and SLOPE in CONFIG and made the default values good everywhere for me. > The next major upgrade was this latest firmware and DSP that the guys have > been working on. It allows RF Gain calibration. Very nice indeed. > > I did write custom s-meter code so that when the first bar on the K3 is > solid and the next one is flickering, I can actually see on my remote > meter the precision of the value as it is swinging up from S1 and down > from S2. For the most part I find flickering bars to be useless. ;-) > > Cheers, > Don > > > > > > > > [Elecraft] [K3] RE: K3 S-Meter and Noise > > Don Wilhelm w3fpr at embarqmail.com > Sun Oct 4 19:43:06 EDT 2009 > Previous message: [Elecraft] [K3] RE: K3 S-Meter and Noise > Next message: [Elecraft] [K3] K3 S-Meter and Noise > Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] > Jim, > > There are 2 reasons I can think of to make that condition 'normal'. > First is if you have the preamp on for a band where it is not needed - > that would amplify the atmospheric noise when the receiver has no signal > present and no AGC is active. If your preamp is on, try tuning it off > and see if it makes a difference. A good test for whether the preamp is > needed or not is to disconnect the antenna and reconnect it. If the > noise level increases when you connect the antenna, there is more than > enough gain in the receiver - turn off the preamp and try the same thing > again - if the noise level still increases when the antenna is > connected, try again but use the attenuator this time. > If you can just barely hear the band noise, that is the proper gain > setting for that band at that time and your antennas. The noise level > on a particular band will vary, perhaps even on an hourly basis (i.e. 80 > meters is noisy during the day, but will quiet down some at night). > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > ----- Dan AB3EN -- View this message in context: http://n2.nabble.com/K3-S-Meter-and-Noise-tp3766928p3768183.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
