[Elecraft] [K2] Re: Was Working Fine... Then HiCur

[Don Wilhelm]

Steve,

Well, I composed a reply to your question earlier, but it apparently was 
not sent, sorry.

That behavior is usually caused by damaged wattmeter diodes in the 
KPA100, but it sounds like you have physically removed the KPA100 and 
that condition still exists.

It appears from your post that you have power control.
Check the voltage as displayed on the K2 display during transmit.  How 
much does the voltage drop?
Recheck T4 and the soldering of the "link" wires, R58, Z1 and Z2.

Please confirm that it is happening with the bare base K2 - no KAT2, no 
KPA100, no KAT100 connected.
If the  above is true, check the DC voltage at the cathode on D9 on the 
RF board - it should be a little above 5 volts with 10 watts actual 
output.  You should also have about that same voltage at Control Board 
P4 pin 10 and the MCU (U6) pin 2.

73,
Don W3FPR

On 4/4/2012 3:03 PM, Steve Dyer wrote:
> Any suggestions or areas I can investigate from anyone?
> 73,
> Steve
>
>
>
>
> ________________________________
> From: Steve Dyer<sdyer at pacbell.net>
> To: Elecraft at mailman.qth.net
> Sent: Tue, April 3, 2012 8:35:04 AM
> Subject: [Elecraft] Was Working Fine... Then HiCur
>
>
> K2 new/old build. S/N is 2338, built base K2 and KNB2 10 years ago, put  away
> and only finished up recently with KPA100, KAT100 and KSB2.
>
>
>
> On air for couple weeks with good results. Suddenly starts giving intermittent
> HiCur messages yesterday.
>
>
> Tore out KPA100 and KSB2.
>
> -Occurs on all bands tested (40, 30, 20, 17, 12, 10) (no dummy  load, but
> checked R with Rig Experts AA-54 and tested close to 50 ohm  points with almost
> no Z).
>
> -Happens with Tune or keying at all power settings
> -Message displays at key-up when hand keying/tune, will happen quickly with
> keyer and then fold-back power.
>
> -Cal Cur is 3.5A
> -Measured power output with external wattmeter (SX-200) and power tracked fairly
>
> closely to setting
>
> -Will not happen if power is lowered to<
> -Checked power supply output voltage with DMM and it matches the K2 display
> voltage +.4V. PS is set to 14V.
>
> -Current draw on 40M @ 12W is 2.3A 13.1V (.5V drop), 17M @ 12W = 3.44A 12.9V
> (.7V drop)
>
> -On 40M Q7 Base is .611V Q8 is .612V
> -Completely disassembled and visually inspected all solder with  magnifying
> glass and re-heated common transformers and chokes in final.  Re-seated IOC and
> MCU (lifted slightly and pushed back into socket).
>
> -Checked T4 windings
> -Have done the DC voltage tests suggested in the various threads about HiCurr
> and everything looks normal.
>
>
>
> 73,
> Steve
> W1SRD
>