[Elecraft] New K2 Owner and a few questions

[W3FPR - Don Wilhelm]

Paul,

Congratulations on your K2 purchase.

The AF Gain pot noise first (it is the easiest).  If your serial number is
less than 3000, you should see if the alternative AF Gain wiring mod has
been installed - if not, I suggest installing it first.  In the process, you
may want to replace the AF Gain pot since you would have the front panel
removed.  Replacement pots are available from Elecraft at a modest price.
If your SN is 3000 or greater (or if the AF Gain wiring change has been
installed in SN <3000), the best solution is to simply replace the pot.  I
have not had much success with any of the pot cleaners that I have used in
the past (that is pre-Elecraft times, so they may have changed the
formulations, but I regress...)

Now for your problems - on the Hi-Cur message, there is likely a problem
somewhere.  If everything is operating correctly and you voltage supply to
the K2 is at 13.8 volts, you should be able to run the CAL CUR at 3.5 Amps
or less and have no HiCur message.  Preliminary steps to take follow:

First thing, check your power supply and its connections to be certain you
are maintaining at least 12.5 volts or more at full power output - tap
DISPLAY and then TUNE to see what voltage is indicated.  If your supply
voltage sags significantly, fix that first and your problem may go away.
Reason: the K2 continues to draw current to satisfy the power output level
you have requested, and if the voltage drops, the current must increase to
provide that current.  The K2 will operate with lower voltage, but it will
draw more current (this is different than many other rigs that simply will
not produce enough power at lower voltages).

If you have a K2/100, first remove the KPA100 and set Cal Cur to 3 Amps,
then check to see if you have the Hi-Cur indication while operating into a
dummy load and see if the base K2 is capable of producing 13 to 15 watts
output on all bands except 10 meters (and possibly 12 meters) where the
power out should be at least 10 watts.

If you can achieve that power output level with the base K2, all is well so
far and the problem is in the KPA100.  If you cannot get that power output
from the base K2, the first place to check is the Low Pass Filter.  Check
each toroid for the proper number of turns - count the turns that pass
throught the center of the toroid (it is not unusual for a builder to put an
extra turn on the core), then check the value of each capacitor in the LPF
(use the schematic to identify the proper capacitor and its value).  If all
is OK there, write another note to the reflector for additional help.

If the base K2 checks out OK, re-connect the KPA100 cables (with the KPA100
laying upside down on a box to the right of the K2), remove the shield (do
not remove the black screws that hold the shield clips in place), and check
the LPF of the KPA100 in the same manner as the checks for the base K2
(toroid turns and capacitor values).  If all is well with the Low Pass
Filter, next thing to check is the KPA100 bias adjustment - follow the
instructions in the KPA100 manual.  And then, check the balance and
calibration of the KPA100 wattmeter (again, as instructed in the manual).

If all the above is correct, you should be able to have an output from the
KPA100 with a CAL CUR setting of 3.5 Amps and have no Hi Cur messages.

73,
Don W3FPR

> -----Original Message-----
>
> In the end I bought one from a member of the list and have today
> had chance
> to play with it.
>
> (snip)
> NOW THE QUESTIONS
>
> What current level is set on most K2 to avoid the Hi Cur warning, I get it
> on a whisle, I have just for now set it to abou 4.5Amps and it
> seems ok with
> that. ( 15 watts o/p )
>
> I have a little noise on the vol pot when I turn it, a friend has the same
> on his K2, is there a good way of cleaning the pot?
>
> Well that’s about it (for Now)
>
> One very happy K2 Owner
>
> 73
>
> Paul
>
> M0BMN
>
>
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