> Hrm. Oh well. I do think that the audio section would benefit from a > rejiggering of quite a few of those caps for more LF.
On the Rx side, there's not much left to consider after the DAC --at least what I can see on the schematic. The circuit path is pretty darn simple. However, the cap fix we've been discussing is really only part of the cure toward establishing a flat low-end receive response to 100 Hz or a bit below. I still see the same effect as measured by Alexander in his link below: http://forum.cqham.ru/download.php?id=44172 There's additional low-end roll-off not attributed to the coupling C after the DAC (again, based on what I see on the schematic). So, the question is "what is causing the remaining roll-off starting around 400 Hz?" To compensate for what Alexander and I are measuring, I need to boost the Rx EQ Band 2 by about +10 dB to get something remotely close to flat between 100-200 Hz. Also, I do not see where Band 1 (50Hz) changes the receive audio response. It's almost as if it's deactivated or something in the analog and/or digital path is causing a sharp HP effect above 50Hz. No amount of cut or boost on Band 1 brings about change on my K3. On the TX side, there are additional C values (or if you prefer, R values), that can be scaled to your liking. I've discussed some of those component size changes on the N1EU website. Also, I believe the newer main K3 DSP Boards may now have re-scaled R values along parts of the affected Tx path. Paul, W9AC ______________________________________________________________ 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
