** Spurious TX sidebands due to C3 installation on early Rev C KPA3 PC boards. **
We have determined that a small number of K3/100s and KPA3s left the factory earlier this year with capacitor C3 installed by mistake on early Revision C KPA3 PC boards. This part location should be empty on Rev. C KPA3s. Installation of C3 causes the PA bias supply to oscillate on some KPA3s at approximately 15-20 kHz, resulting in spurious TX sidebands at that spacing from the carrier. S/N & Date Range: A small number of K3/100s within approximately S/N 3000-3138. These radios were shipped approximately April 30 to June 2, 2009. Upgrade or repair KPA3s sent separately during this time period may also be affected. After June 2, 2009, this problem was corrected for all K3/100s s/n 3139 and later, and all Rev C KPA3s bought as an upgrade. This alert does not apply to Rev C KPA3s shipped after June 2, 2009. Symptom: A strong TX spur, approximately -20 dB down from peak transmit power, spaced approximately 15-20 kHz on each side of the operating frequency. Corrective Action: Remove capacitor C3 from the Rev C KPA3 PCB as described below. A Tech. Alert App note (.pdf) can be downloaded from: http://www.elecraft.com/K3/mods/K3%20Technical%20Alert%201.pdf It contains detailed info and pictures. Its also linked to from our K3 Mods and App notes Page: http://www.elecraft.com/K3/k3_app_notes.htm We apologize for this issue. We thought we had contacted all of the K3 owners affected, but we have found a few we missed, so we are posting this here. If after reading the Tech. Alert you have questions, please feel free to contact our Tech. group at [email protected] or via phone at 831-763-4211 73, Eric WA6HHQ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
