Wow. That will certainly explain the drop in RF power output. I would not suspect corroded pins on the KPA connectors since resistance there will limit the current the PA can draw and actually reduce the voltage drop.
Are you looking at the voltage reported by the K3's display? If so, can you check the output of the power supply to confirm that it is not drooping under load. Next, I'd carefully inspect the power cable from the power supply to the K3 - especially the connectors. If your power supply has bolt-on terminals for the power cable, be sure they are tight (I've seen Astrons shake a nut loose through the low level vibration from the power transformer over a period of months when they weren't tightened properly in the first place). At the other end, is there any discoloration in the contacts in the powerpole connecter? Are the contacts fully inserted in the housing? Do you have anything else between the power supply and the K3 - power distribution box or in line fuses, etc? If so, they can introduce the resistance causing the voltage drop through a bad contact. 73, Ron AC7AC -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ian Kahn - Ham Sent: Monday, December 24, 2012 7:18 AM To: [email protected] Subject: Re: [Elecraft] New Output Power Issue Update on my low output issue: I ran the TX Gain Calibration this morning, and everything passed with flying colors. I am seeing about a 4-4.5V drop across the radio when going from rx to tx. Rx voltage sits at 13.8V, but when I transmit, voltage across the rig drops to between 9 and 9.5V. All tests performed while tuned into a 300W dummy load. Before I tear into my rig and start looking for corroded tin pins on the PA board (K3 #281, so unlikely the board was replaced/mod performed), is there anything else I should test while my station is still all together in one piece? Thanks to everyone for the assistance, and Merry Christmas! 73, --Ian Ian Kahn, KM4IK Roswell, GA EM74ua [email protected] K3 #281, P3 #688 HRD v5.x/6.0 Test Team On 12/23/2012 5:07 PM, Don Wilhelm wrote: > Chuck, > > It could - defer decisions on that until after doing the TX Gain > Calibration. > > 73, > Don W3FPR > > On 12/23/2012 5:01 PM, hawley, charles j jr wrote: >> Could it be/affect a 40% difference? >> >> Chuck, KE9UW >> Lionel Trains, TCA, LCCA, LRRC >> aka Jack, BMW Motorcycles BMWMOA #224 >> > > ______________________________________________________________ > 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 ______________________________________________________________ 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 ______________________________________________________________ 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
