[Elecraft] K2 ..K2 100w ATU .. hirefl current error and then over current failure

stephen pearce pearce.sg at gmail.com
Thu Jan 12 03:49:48 EST 2012


Does anyone recognise this pattern ..
k2 100W
kat100 (rev b board)

..
apparently intermittent error ...
initially hirefl current error on auto tuning ...
then overcurrent failure of power supply when auto tuning at high current ...

rx working fine ... in kat100 ant1/ant2 relay seems to be ok .. as is
hi/low current relay
and all the L and C relays for the auto tuner seem to click in
appropriately when you run through them in the set up menu on the k2

I've inspected the board in the kat100 and there are no obvious dry or
loose solder joins ...

If you tune at sequentially higher power settings starting at 0.1,
then just under 10 (so as not to trigger the high power relay )
then just above 10w then 20+w .. then full power it seems to avoid the
over current failure of the supply ..

Why the supply (which is mfj4125) is cutting out (it must have a
resettable fuse as it recovers  after about 30 sec) puzzles me ..
previously I have observed the k2 shut itself down before this happens
.. and makes me wonder if rf is getting into the supply ..
particularly if there is an initial significant mismatch in the atu
before it completes its auto tune

I have tried "init" reset in the k2 atu submenu .. as well as the cal
routines ...

tried transmitting into dummy load and into antenna ...neither seems
to make a consistant difference ...

possibly there is a fault in the fwd/refl power sensing in the atu ..
but this should not produce over current cut out in the supply

(this k2/kat100 is a friends ...I tried substuting my kat100 .. which
seems to work ok with his k2)


Any suggestions appreciated ...

73s
zl1any


-- 
Stephen Pearce
Critical Care
Whangarei
ph 021 390 997


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