Don Wilhelm-4 wrote: > > My conclusions: I am not certain what K3 owners are perceiving as noise > any more than I had been before these tests. The flatter passband of > the K3 may be sub-consciously perceived as being more 'harsh', but I > could not equate that to 'noise'. The other filters with a high end > in-passband response that drops off similar to a "pink noise" response > *could* be causing a perception of additional noise *if* their local > noise has significant content in the 2 kHz to 3 kHz range - yes, the K3 > will make this section of the audio spectrum louder than the other > receiver I measured. The "audio hiss" is not coming from the high > frequency spectrum outside the passband because in that area, the K3 and > the K2 are much more quiet than the others measured. >
I used Spectran rather than Spectrogram which has the advantage that it can also be used interactively as an audio filter. I found that decreasing the bass content by increasing the frequency of the high pass filter made the audio seem more noisy. I presume this is because high frequency noise components then comprised a greater proportion of the signal and were emphasized. I think that if people were using low impedance headphones and the original DSP board with small value coupling capacitors then they would find the audio over-bright and harsh, as I did. I tried different AGC settings and agree that lower AGC THR settings make the radio sound more noisy, so that may also be a factor. I am now using AGC THR = 8 which is the maximum and might well use a higher setting if it was available. I am also using AGC SLP = 1. Having identified the problems and made some adjustments to settings the K3 sounds really good now on high impedance phones and on the internal speaker. ----- Julian, G4ILO. K2 #392 K3 #222. * G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html -- View this message in context: http://n2.nabble.com/Re-K3-receiver-noise-questionable-test-results-tp4192141p4193141.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
