Wayne Is the low pass filter module available separate from the entire DSP Rev C board replacement? If so, what does it cost and how complicated is it to install? Buck k4ia K3 #101 In a message dated 12/18/2009 10:12:29 A.M. Eastern Standard Time, n...@elecraft.com writes:
The K3 has a lot of overall gain. This is necessary to provide sufficient speaker output in operating locations with high ambient noise levels. But you can adjust the amount of gain, and shape it, to meet your needs. If you feel that the noise level of your K3's receiver is excessive, please try the following: 1. Turn off the preamp. In many cases it is not needed (especially below 20 m), because the receiver is still very sensitive working directly into the mixer. 2. If overall AF gain is higher than needed for your headphones or speaker, set CONFIG:AF GAIN to LOW. This makes the K3's audio output level (and overall gain) very similar to a K2. 3. Use the factory defaults for AGC. These were carefully chosen to adjust gain in the presence of significant band noise. 4. Use narrow filter bandwidths when listening to narrow-band modes (CW or DATA). Noise output is proportional to bandwidth, and in narrow- band modes, reducing WIDTH can dramatically reduce the signal-to-noise ratio. I strongly recommend installing at least one narrow crystal filter (500 Hz or lower) if you use CW or DATA modes. The K3's entire receiver philosophy is built around the use of roofing filters that are matched to the operating mode. 5. Use noise reduction. NR is specifically designed to reduce wideband stochastic (white) noise. I suggest using the lowest setting (F1-1) to obtain a modest noise-reduction benefit with minimum impact on signal characteristics. 6. If you're sensitive to high-pitched noise, consider installing (or having us install) the new DSP low-pass filter (LPF) module. (Contact k3support for details.) This filter rolls off everything at about 4.5 kHz, including some low-level AF sampling artifacts from 10-14 kHz that some operators with excellent ears can hear. The LPF module, which is easy to install, can improve the overall listening experience. It has already been phased into production. 7. If you still feel that noise level is too high, try doing an MDS (minimum-discernable signal) test to see if the receiver is meeting spec. You can use your own signal generator or an Elecraft XG1 or XG2, in conjunction with the K3's built-in true-RMS AF voltmeter (see alternate VFO B display modes in the owner's manual). 73, Wayne N6KR ______________________________________________________________ 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 ______________________________________________________________ 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
