Gary Surrency to Jarno

Hi Jarno,

You might have a damaged relay in the lowpass filter if just 20m or 17m
does not work now. Use the RF probe in the kit (or an oscilloscope if
you can), to see if there is a loss of RF signal through the PA to
antenna signal path when on 17m or 20m. Also see if there is RF on the
lowpass filter toroids for any other band than 30/20m, when transmitting
on those bands. If so, a relay may be stuck or welded in the in-circuit
position, which will detune the PA stage greatly.

You can also check the VCO voltage and signal freq. at TP1 when on 17m
or 20m, to see if it is correct and if it falls within the limits shown
in the manual for the VCO voltage tests, and if the VCO frequency is
close to that shown in the VCO Table on the page just before the
schematics begin. The VCO freq. shown is with the VFO knob tuned to the
bottom end of each band.

Note that the KPA100 speaker should have a cupped metal magnetic shield
placed over its magnet, to prevent the magnet from affecting the VCO
relays in the K2. If not, order it from parts@elecraft.com.

Another possibility is there is a cold or missed solder connection
somewhere in the RF signal path. Inspect the PCB, the parts, and all
connections very closely for that, and try reheating all connections in
the suspect areas just as a precaution.

REMEMBER:

NEVER transmit with the heat sink of the K2 or the KPA100 removed, or
the PA transistors will be damaged. If there are any signs of heat on
the tabs or the PA transistors, or if the nylon shoulder washers are
melted, the PAs are probably damaged and will need to be replaced.


Always check the basic K2 without the KPA100 connected at all, and get
it working before reconnecting the KPA100. Don't just disable the KPA100
from the K2's menu - remove the KPA100 completely.

Use caution when soldering or repairing the kit, that none of the relays
are accidentally damaged with the soldering iron. Even a minor burn on
the relays can prevent them from working.