[Elecraft] K3 - no output power

[Christian Janssen DL1MGB]

Hi all,

just wanted to let you know that my K3 is back again with full output power.

We found the Diode D1 on the LPA board. On the anode side, it had shown full power, on the other side, nothing. When unsoldering it, it was already very loose. The diode itself was intact, but had no contact at all. Most probably it got loose after heating up and unsoldering itself. New diode soldered in, TUNE, smoke. After comparing some voltages around the diode, we found Q6 to be faulty. That's why more than the maximum rated current of 1A flowed through the diode. Changed also the transistor and now everything was working again, full power, no smoke, no smell.

Most probably, it has to do with the same problem as DK3WE already experienced 8 years ago: http://www.the-mule.de/?p=1275#more-1275 

Many thanks again for DD0VS for helping me in finding the faulty parts!

73s Chris DL1MGB




Am 24.03.2021 um 21:03 schrieb Christian Janssen DL1MGB:
> Hello,
> 
> it happened during the Russian DX Contest last Saturday, from one second to another. No output. When I tune the display looks like this: http://dl1mgb.com/temp/k3_no_power.jpg
> 
> Following conditions:
> 
> - sending into a 50 ohm dummy load
> - no matter how many watts are set with PWR knob
> - Test mode off
> - TX INH off
> - all driver transistors working (three screw test)
> - no output power also on external watt meter
> - happens on all bands
> - happens with KPA set to "not inst"
> - knocking on housing doesn't change anything
> - when starting the antenna tuner, it says 5.0 watts, but no output on the external watt meter
> 
> I am running out of ideas :-)
> 
> 73s Chris DL1MGB
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