On Wed, 2 Mar 2005 08:00:59 -0800 (PST), John Magliacane wrote: > > > --- [EMAIL PROTECTED] wrote: > >> I use my K2 on CW and SSB. I was wondering how K2 Hams would feel about >> different >> grades of SSB adapters. >> > I would sharpen up the skirts on the audio chain (300 - 2700 Hz) with > active filters prior to the compressor. (There is no reason for any energy > outside this spectrum to be passed along (and influence the operation of) > the compressor and the balanced modulator, since the crystal filter is too > narrow to pass it, anyway.) >> >> Reducing the values of the coupling capacitors in the audio chain makes a >> big >> difference (what purpose an audio response that goes down to 30Hz ?!) > > Add some gain (accomplished through the active filtering stated above), and > provide a mic gain control (on the board). > >> Get rid of the mic attenuator circuitry (does anyone use it ?) and add an >> adjustable mic gain of 10dB (well rf filtered) to the board.
>> Replace the existing compressor IC with a later version that has an >> adjustable threshold level. >> Totally revamp the VOX circuitry and add Anti-VOX. Make both hardware >> adjustable. > It might be nice to replace the NE602/NE612 with a switching-style > balanced modulator for the following reasons: > > * The BFO (VXO) injection voltage into the NE612 varies with the BFO > setting and USB/LSB switching. The NE612, being a linear mixer, is > sensitive to this. It's DSB output voltage varies according to the BFO > injection voltage, as does it's carrier suppression. > > * A well-designed switching mixer is inherently self-balanced (assuming > matched resistors, minimal stray capacitance, and low offset voltage > OP-AMPs are used), eliminating the need for the carrier balance control > and one less adjustment for builders. > > * More dynamic range (limited only by the output swing of the audio feeding > the modulator and the supply voltage to the analog switches), leading to > even less SSB TX distortion (IMD) and carrier suppression than is > possible now. > >> I would like to know more about using a switching mixer for the BM. >> If the circuitry does not get too complex or introduce problems it would be >> worth trying. Please let me have more information. >> 73 >> Stewart G3RXQ > Good luck with the project! > > > 73, de John, KD2BD > > > ===== > Visit John on the Web at: > > http://www.qsl.net/kd2bd/ > > > __________________________________ > Celebrate Yahoo!'s 10th Birthday! > Yahoo! Netrospective: 100 Moments of the Web > http://birthday.yahoo.com/netrospective/ > _______________________________________________ > Elecraft mailing list > Post to: [email protected] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
