After seeing this report I pulled the Rev C PCB (the only PCB we have shipped for this product) and took a good look at it, then looked at the docs and finally the Gerbers for the board. R12 and R13 on the KRC2 PCB are properly labelled. R12, closest to the switches, is a 4.7K ohm resistor (yellow-violet-red) used to pull the RS232 line to -12V. R13 is next to it, closest to the DE9 connectors is a 47 ohm resistor (yellow-violet-black) and provides +12V power for the JFET. The legends on the PCB and in Figure 10 of the KRC2 Rev C manual are correct.
Now, what caused you to think they were backwards? And, let’s make sure that you do have a Rev C board in your KRC2. 73, Jack, W6FB > On Nov 19, 2020, at 11:58 AM, Paul Fletcher via Elecraft > <elecraft@mailman.qth.net> wrote: > > FAO anyone who's had issues getting the serial comms working on a KRC2: > > R12 and R13 are transposed on the silkscreen on the PCB. I fell foul of this > when I recently built my KRC2 and it wouldn't communicate. After quick probe > around it was evident there was no negative voltage to the RS232 driver, U2. > A little further probing revealed no 12V present at R13 but there was at > R12. It was then I realised the component layout in the manual is different > to that marked on the PCB. A quick swap of resistors and everything works as > it should. > > I've re-read the errata and the manual and there is no reference to this > issue. Apologies if it's been flagged up on here already but I couldn't find > anyone pointing this out though there do seem to be a few people with serial > comms issues with the KRC2. > > Hopefully this is of assistance to someone. > > 73 Paul M1PAF > > ______________________________________________________________ > 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 jackbrin...@me.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
