Don Wilhelm-4 wrote > Yes, those two mods are old, and apply only to the A level boards (below > SN 3000). > There have been improvements in the K2 sidetone incorporated into the B > level boards, and are also included with the A to B mod kit. > The changes added a 47k resistor in series with C24 (R11 for the B level > boards) and a shielded 82mH inductor across pins 7 and 10 of RP5. > The sidetone is still not a pure sine wave, but it is close if your > sidetone pitch is between 500 and 700 Hz. > > Those old mods would be applicable to unmodified A level boards but > re-design of the circuits would be required for the B level boards and A > level boards already modified with the A to B upgrade kit.
Don I beg to differ. From LA3ZA's K2 mod site: ######################################## Sidetone mod Updated Nov 2006 Even more sinusoidal tone than the mod in serial #3000+ gives Important to have an inductor with correct series resistance (KT5X) Simple, one more capacitor TF3MA ############################################ I installed this mod in my S/N 4119 and it made a huge difference in sidetone quality. The original design had so much harmonic content that it was difficult to zero beat stations by ear. 73, Bill W4ZV -- View this message in context: http://elecraft.365791.n2.nabble.com/latest-K2-serial-tp7615395p7615492.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com