[Elecraft] K1 with Issues

[Don Wilhelm]

Chuck,

Make certain you have a dummy load connected to the K1 (it is 
transmitting) and continually tap the WPM- button to try to lower the 
power level for the testing that you need to do.

Theory:
The K1 uses one MCU pin (KEYIN) as an analog input to determine whether 
the dot paddle, dash paddle or both have been closed.  The resistors 
that determine the 3 levels are on the RF Board.
R19, R20, and 2 sections of RP5.  The voltage at pins 4 and 5 of RP5 
will determine the static voltage of all points in the circuit.

What to do:
Measure the voltage at pins 4 and 5 of RF Board RP5 and compare with the 
voltage at Front Panel U1 pin 5.  They should be the very close to the 
same voltage.  If not, check the values of R19 and R20 and re-flow the 
soldering of RP5, R19 and R20.

If you had ever attempted to clean the flux from your K1, that could be 
the cause.  If some flux cleaner residue wicked up under the key jack, 
it can create a leakage path which would explain your problem.  The only 
cure is to remove the key jack and clean both the board area under the 
jack and the bottom of the key jack.

It is conceivable that the key jack itself could have some kind of 
leakage path inside.  To check, you will have to remove the key jack and 
replace it if necessary.

Do the solder re-flow first - a bad connection can work fine for a 
while, and then fail later after a bit of oxidation occurs.  If that 
does not cure it, remove the key jack and check again with the jack 
out.  Replace the key jack if required.

73,
Don W3FPR

cstoverva at aol.com wrote:
> My K1 (sn2450) went together back in Oct 07 without a hitch and has been working flawlessly ever since.
>
> A big glitch showed up tonight.? When I pushed the attenuator button it started transmitting dashes.? That cleared by cycling the power.? I then tried sending the content of memory 1.? It began sending that message, stopped, "end" appeared in the display, then started transmitting alternating dots and dashes.? When locked in transmit, the display blanks out.? Initially I verified that it was transmitting with another receiver, but now it seems to have lost output too.? It was hooked up to a resonant antenna or dummy load, so I wouldn't think the final fried.? I'm running it off a supply at 13.6VDC.? 
>
> A voltage check of RA3 pin 5 of the MCU shows 5.6V with both dot and dash contacts open.? When the WPM-/attn button is held the dashes start sending and the pin 5 voltage drops to 5.0 even? though the contacts are still open.
>
> I've been awake too long and not much is making sense, so I'm going to call it a night.? Any ideas or suggestions on where to look would be greatly appreciated.
>
> Chuck? K4QS 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com 
> Version: 8.0.238 / Virus Database: 270.11.57/2060 - Release Date: 04/15/09 06:34:00
>
>