Chip, I suspect that you accidentally toggled the sidetone source in the menu. If your K2 SN is 3000 or greater, or you have an earlier K2 with the KPA100 or KIO2 added, you need to select U8-4 for the sidetone source. If none of those conditions match, the sidetone source is U6-25.
If you put Q5 back in the circuit, enter the menu for St L, hold EDIT to edit the parameter, and first set the level at something reasonable - between 20 and 40 - then tap the DISPLAY button to toggle the source. When you hear sidetone, stop and exit the menu. To prevent future occurrences, I suggest that you do not set a PF key to St L. When zero-beating, adjust the audio level on the signal (to match the sidetone level) with the AF Gain control instead of adjusting the level of the sidetone to match whatever signal level you have. 73, Don W3FPR On 7/28/2011 7:37 AM, Chip Stratton wrote: > My K2 suddenly quit supplying a sidetone. Changing sidetone level and > frequency do nothing. > > Per the troubleshooting guide, I've found that the drain of Q5 has no AC > voltage when key down, while pin one of U10 (IIRC) is supplying 5 volts (and > pin 25 of the IC in the previous step had expected 2.5v AC). > > So, this seems to mean that Q5 is bad, but when I pulled it and tested it > with the M3 semiconductor analyzer, it is not obviously bad (to me anyway). > It reads NMOS Vth=1.76v, S-G-D mA=1.13 - whatever that means, I don't know > enough to interpret. > > Any off the cuff ideas? I have a replacement 2n7000 on the way, but still > wondering why it would fail in circuit, and if its really bad. > > Thanks, > Chip > AE5KA > ______________________________________________________________ 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
