[Elecraft] KRC2 silkscreen gotcha

[Jack Brindle]

Please do. Also, please also send a picture of the label on the bottom side closest to the front of the device.

Jack, W6FB
Elecraft Engineering


> On Nov 19, 2020, at 1:47 PM, Paul Fletcher <paul_fletcher at me.com> wrote:
> 
> I have a Rev C PCB and the silkscreen does not match the diagram in the Rev C manual. On the PCB R12 and R13 are marked the opposite way round to the manual. I can send pics if you want them.
> 
>> On 19 Nov 2020, at 21:33, Jack Brindle <jackbrindle at me.com> wrote:
>> 
>> 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 at 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
>>> 
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>> 
>