Many thanks for your reply Peter. The Rev C schematics are the ones on the current Elecraft website, which I have. I was suspicious of the pins which are the originals, but they look OK and Deoxit has not cured the problem. Yesterday my order of some ribbon cables arrived, and I was able to run the KPA3 outside the chassis upside down. On demanding more than 12 W power there was a rapid smell of hot electronics but no smoke. The 2 x 51 ohm 3 W grey resistors were hot enough to cause a minor burn! I have still to determine where the rest of the power is going - the transistors?
If you have any details of the bias setting method, that would be really helpful. I have not been able to find any information on this on the internet. Thanks for the good luck - I need it. 73, Ted G7BQM > On 23 Feb 2019, at 12:29, Peter Torry <[email protected]> wrote: > > Hi Ted, > > I have the schematics from 2008 but they were rev C if they are of use to you. > > There was an issue with the KPA100 which was cured by fitting new gold plated > connectors, free from Elecraft but just try removing the PA and refitting it > to remove any issues with oxidation of contacts. De-Oxit is good for this as > well. Could be worth checking the bias setting. > > Good luck with the repair. > > 73 > > Peter > > G3SMT > > > On 23/02/2019 12:14, Ted G7BQM wrote: >> Hello All, >> >> I have recently acquired an early K3 which needs tidying and checking over. >> So far all appears to be OK except for the KPA3 which gives no RF output but >> the rig draws 14 Amps regardless of the power setting. The LPA is working >> fine with up to 12 W RF out and a max current draw of 4 W. >> >> Visual checking of the KPA3 board reveals nothing amiss but also shows >> considerable component differences compared to the only schematic I could >> find on the Elecraft website - the Rev C version. >> >> If any of you early adopters have a .PDF schematic for the KPA3 Rev B, I >> would be most grateful for an electronic copy. >> >> 73, Ted G7BQM (with quite a lot of Elecraft stuff!) >> >> >> >> >> ______________________________________________________________ >> 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
