K2 High Current

[n0jrn]

Gang:           Just curious !

How high have did you set your current limit ???

My K2 has every option available ( 10 watts ) and I'm running my Graph set
to BAR with back lighting on.

Just got a new power meter and noted my actual output is about half what I'm
setting it with power control.

I do get a high current warning when I run it up around 10 watts but not
when I running around 5.

Just wondering if I need to go back through part III alignment and set my
current limit higher.

Any ideas ???

Thanks and hopefully see some of you on RFTB Sunday evening.

72         Jerry           N0JRN

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[Don Wilhelm-4]

Jerry,

Set the CAL CUR to 3.50 Amps - I know the manual says 2.50 Amps, but
many K2s will develop more than 15 watts and that requires more than
2.50 amps when the power control is set to "full right".  I do not
recommend operating that way, limit the power setting to 12 watts or less.

Being a QRPer, if you wound T4 for "better efficiency at 5 watts",
change it to the normal winding ratio if you will ever operate SSB or
operate over 5 watts - better efficiency at 5 watts also means worse
efficiency at powers over 5 watts, and the PA load will not be correct
for linear operation.

Another thing to check is the DC voltage at the K2 end during transmit.  
Tap DISPLAY and then do a TUNE while observing how far the voltage
drops.  If it is more than a few tenths of a volt, check the connections
for your DC cable to the K2 because it has too much resistance
somewhere, either from too small a wire gauge (#18 or #16 is fine) or
connections that are not tight or severe sag at the power supply itself.
The K2 will attempt to develop full power even with reduced voltage, and
that means the current must increase if the voltage is low.  That also
is a feature that allows the operator using batteries to use the CAL CUR
setting as an indicator of low battery voltage - when the HI CUR
messages start, the battery voltage has dropped too low.

If all the above have been checked and found to be OK, then look
carefully at the Low Pass Filter.  Count the turns on the toroids again
(count the number of times the wire passes through the center of the
core.  One too many turns is a frequent builder error.  Just running a
straight wire through a toroid center is one turn, one full wrap around
the core is two turns.

73,
Don W3FPR

n0jrn wrote:

> Gang:           Just curious !
>
> How high have did you set your current limit ???
>
> My K2 has every option available ( 10 watts ) and I'm running my Graph set
> to BAR with back lighting on.
>
> Just got a new power meter and noted my actual output is about half what I'm
> setting it with power control.
>
> I do get a high current warning when I run it up around 10 watts but not
> when I running around 5.
>
> Just wondering if I need to go back through part III alignment and set my
> current limit higher.
>
> Any ideas ???
>  
>

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Elecraft mailing list
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html