Jack, > The short story is 2nd harmonic is at least 80 dB down and the > 3rd harmonic is 76 dB down. Fourth and fifth harmonics are in > the noise and not visible. An artifact at 3.9 KHz is also visible, > although quite far down compared with the desired signal.
That is remarkably close to what I measured with my K3 in CW with a Heil Proset as the load. I posted those results on Thursday. I've run them again in USB with a 500 Hz reference tone. DSP is set to 2800, center frequency is 1500 Hz (default). Signal source is an XG-2 (50 uV/-73 dBm) and ACG is Slow. 200 Ohm (Heil Proset) headset 500 Hz ---------------- Harmonic ------------------- Reference 2nd 3rd 4th 5th 6th 7th 8th 9th ============================================================ +4 dB -64 -45 -79 -47 -81 -49 -78 -51 +3 dB -66 -78 nf -83 nf -92 -98 -93 0 dB -68 -79 nf -82 nf -89 -95 -93 -10 dB -76 -75 -80 -82 -84 nf -86 nf -20 dB -72 nf -73 nf -75 nf -76 nf -30 dB -64 nf -62 nf -65 nf -66 nf 0 dB is .7 V RMS (1V Peak) measured for the reference tone across the headphone element - total audio level will be somewhat higher with distortion/noise. "nf" indicates the harmonic product not measurable (in the noise floor). Note: at +4 dB, the audio amplifier is in clipping and there are additional IMD products approximately +/- 200 Hz from the reference and each of the odd harmonics. 73, ... Joe, W4TV > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jack Smith > Sent: Saturday, September 06, 2008 2:14 PM > To: Paul Fletcher > Cc: [email protected] > Subject: [Elecraft] Headphone Output - SSB Mode - Single Tone > > > At the request of Paul, M1PAF, I've measured the harmonic distortion > seen at the headphone output in a K3 operating with with 2.7 KHz > bandwidth USB mode with a single tone at 500 Hz offset. This > allows up > to the fifth harmonic to be within the DSP passband. > > The details are at > http://www.cliftonlaboratories.com/elecraft_k3_receive_audio.htm. > > Audio level is set for a comfortable listening level with a Heil > Pro Set, corresponding to about 30 mV RMS. > > The short story is 2nd harmonic is at least 80 dB down and the 3rd > harmonic is 76 dB down. Fourth and fifth harmonics are in the > noise and not visible. An artifact at 3.9 KHz is also visible, > although quite far down compared with the desired signal. > > Jack K8ZOA > www.cliftonlaboratories.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 _______________________________________________ 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
