As a new K3 owner, it is entirely possible I am treading ground already well trodden. My apologies should this be so.
While waiting for delivery of an Inrad 500Hz roofing filter, I have been accumulating experience with S/N 4904. I am enjoying my new rig greatly, although I confess to finding an odd thing or two puzzling. One of these relates to the level at which wide AGC has been set. My primary shack transceiver is a home built, G3XJP designed Picastar, which has a similar architecture to the K3 but is based upon the much older Analog Devices ADSP2181 and AD1885 AC'97 codec. Unlike the K3 with its multiple choice roofing filter bandwidths, my Picastar uses a single 4kHz wide roofer in all modes. The thing puzzling me is that I find de-sensing by strong signals within roofer b/w but outside DSP b/w far more noticeable on the K3 than on Picastar. I expected the opposite to be true given the Picastar codec has only a 16 bit ADC whereas the K3 has 24 bit. A quick measurement reveals K3 wide AGC threshold around 70dB above MDS whereas on Picastar it is closer to 80dB. With Star's 16 bit ADC this equates to around 10dB headroom whereas the K3's 24 bit ADC implies headroom in excess of 30dB. On the face of things it would appear some 20dB of extra defence against strong signals in the no man's land between roofer b/w and dsp b/w has been sacrificed. I am wondering why? Perhaps I am missing something? Thanks. Bob, 5B4AGN ______________________________________________________________ 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
