Pete Smith N4ZR wrote: > > Ever since I got my K3, I have been a little surprised at what seems to > be a relatively high noise level with no antenna connected (or on a > dummy load). Very unscientifically described, on 20m it registers 1-2 > bars on the S meter, and the background is quite loud on the speaker > with the audio gain set at 12 o'clock (RF gain full, AGC - fast, > bandwidth 200Hz with a 500 Hz roofing filter in, no noise blanker or > noise reduction). >
Pete this is a common issue for new users. It's actually not unique to the K3...Orion had the identical issue for the same reasons. 1. Your gain settings are incorrect. If AF Gain is at 12 o'clock it's too high, and RF Gain should almost never be at maximum. My settings are typically AF Gain at 9-10 o'clock with RF Gain around 1-3 o'clock (but that depends on the specific antenna and band). This has been covered many times and Barry N1EU has a nice explanation including a summary of how to set both gains here: http://n1eu.com/K3/K3_agcgain.htm (scroll to Gain Adjustment) 2. The K3's S-meter is more accurate than most rigs, especially at the low end of the meter scale. Typical FT-1000 meters will read S1 at a -104 dBm level. http://www.n6rk.com/FT1000_S_meter.doc By contrast, a properly calibrated (and accurate) K3 meter will read S4 at the same level! http://www.n6rk.com/S_unit_definitions.doc The combination of #1 above (setting RF Gain to max) and #2 (an accurate meter which indicates higher than many rigs at low levels) leads many new users to think the K3 is noisy. In fact it isn't but we need to learn how to properly set gain to take maximum advantage of the K3's dynamic range. K3NA's version is very detailed, but N1EU's version above is much simpler. BTW for those of you with a P3, setting it's Ref Lvl just at or slightly above the noise floor is the equivalent of what you're doing in the K3 above. When done properly with the K3, you'll hear weak signals at the noise floor and still have the full ~100 dB of dynamic range above that level. If you set RF Gain too high, the rig will sound noisy and you'll be wasting some dynamic range by extending the K3's low end below band noise levels. 73, Bill -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-High-internal-noise-level-tp5472376p5472506.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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
