[Elecraft] KRC2 silkscreen gotcha

[Paul Fletcher]

The circuit diagram and the parts placement in the manual are correct. On mine it was the silkscreen for R12 and R13 that was reversed. Let Jack do some digging as it’s possible (from his comments) that this doesn’t affect all boards. Mine only arrived a few days ago. The easy way to check if there is an issue is to check there is the correct negative voltage on pin 8 of U2. Mine was almost 0V before swapping the resistors.

> On 19 Nov 2020, at 21:41, Rich <rwnewbould at comcast.net> wrote:
> 
> Thanks for the info.   Could you post the correct value of R12 and R13?
> 
> Mine was back at Elecraft way back.   I want to make sure it is already not corrected
> 
> Based on your info R12 should be 47ohm, correct?
> 
> 
> Thanks
> 
> Rich
> 
> On 11/19/2020 15:52 PM, Paul GACEK via Elecraft wrote:
>> Hi Paul
>> 
>> Thanks for the heads up.
>> 
>> I had some communication issues with my KRC2 in that it worked like a champ with my K2 but not so with my KX3.
>> 
>> I’m going to crack open my krc2 shortly and see what values I have in those two resistor locations.
>> 
>> What radio where you using with the KRC2?
>> 
>> Paul
>> W6PNG/M0SNA
>> www.nomadic.blog
>> 
>>> On Nov 19, 2020, at 12:47 PM, Wes <wes_n7ws at triconet.org> wrote:
>>> 
>>> Thanks.  I've owned one of these for years and as I recall, it's always been a problem so it's been resigned to the junk box.
>>> 
>>> Maybe I can resurrect it to make it useful for something.
>>> 
>>> Wes  N7WS
>>> 
>>>> On 11/19/2020 12:58 PM, Paul Fletcher via Elecraft 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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