I had this same exchange with Eric earlier today ... 1) the LPF board will be available "shortly." It is in stock and will added (along with instructions) to the web page soon (I read that as the next day or two).
2) The DSP upgrade now being shipped is "Rev D" which is "Rev C" (the low frequency enhancement) plus the LPF board (the ADC spurious elimination filter). I did not get price information on the LPF board but was assured it will be up with the rest of the information. 73, ... Joe, W4TV > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of [email protected] > Sent: Friday, December 18, 2009 5:11 PM > To: [email protected]; [email protected] > Subject: Re: [Elecraft] K3 Receiver Noise Level -- Evaluation > and Adjustment > > > 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, > [email protected] 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
