Hi Martin, Do you observe (or hear) sidebands outside the nominal transmitted bandwidth with CW transmissions or only SSB transmissions?
Can you perform a 2-tone test with an audio source other than speech? The fact that the unwanted sidebands are not observed when the KPA3 100 watt amplifier is bypassed suggests a possible change in the bias point of the PA transistors. If you have the original BJT version of the KPA3, not the LDMOS version of the KPA3A, perhaps you can measure the base or collector bias current when the KPA3 is engaged (PWR control set at 12 watts or above) with no audio modulation applied. That may be difficult to do without temporarily lifting a component lead. Perhaps Keith, WE6R from Elecraft can suggest a way of confirming proper bias point setting for the KPA3 without too much intrusion? 73, Mike, K8CN ______________________________________________________________ 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
