[Elecraft] Question about K2 power meter

Mon Apr 23 09:48:55 EDT 2007

Jeff,

If you are saying that you see an occasional jump from 120 watts power 
to 140 or even 160, I would say that *MAY* be possible, but if it jumps 
from 50 (or even 80) watts to 160, then you do have a problem - and my 
first reaction is that it is an indication of a transient oscillation.

How long does the power stay at 160 watts?  Is this on 40 meters, or 
does it occur on all bands?  What level is your KPA100?  If it has RFC10 
installed and the L15 position has a toroid and L16 has a toroid with a 
red core - you do not have the latest update - that update was designed 
to combat a parasitic on 40 meters.  In your case, I would recommend the 
KPA100UPKT if it is not already installed just to be rid of the 
possibility that the 40 meter parasitic is what is causing your problem.

73,
Don W3FPR

Jeff Kinzli N6GQ wrote:
> Thanks Don and others for the answers.
> 
> In my case, I'm trying to run down a proble where the KPA100 will be
> fine, then all of a sudden it's output will jump up over 140W. I
> thought that the high output in the base K2 might be the cause. So are
> we saying that some variation is ok, and once in a while if the KPA100
> gets up over 150W then we're ok? This is not apparently an oscillation
> issue, as I don't see high SWRs.
> 
> Thanks,
> 
> Jeff
> 
> On 4/23/07, Don Wilhelm <w3fpr at earthlink.net> wrote:
>> Jeff,
>>
>> That is normal behavior - the power will climb a bit if left in TUNE for
>> a period of time.  It is mostly the result of heating in the PA
>> transistors.  In normal operation, either with CW or SSB, there is not a
>> constant carrier being transmitted and the same conditions will not be
>> present.
>>
>> Do not leave the K2 in TUNE at high power for any significant length of
>> time - remember that TUNE is transmitting at a 100% duty cycle.  OK for
>> short bursts, but not good for longer periods.  The base K2 shoud be
>> limited to 5 watts or less for a 100% duty cycle transmission and to 35
>> watts or less with the KPA100.
>>
>> 73,
>> Don W3FPR
>>
>> Jeff Kinzli N6GQ wrote:
>> > Hi Don,
>> >
>> > Thanks for the replies.
>> >
>> > To answer your questions, the problem occurs into a dummy load.
>> >
>> > I set the base K2 (without KPA100 connected) to 5.0W, and then TUNE,
>> > and it starts at 5.0W and heads upwards to 5.7-6.0W (read from the
>> > display, as well as the S-meter). After about 10 seconds in TUNE, it's
>> > up to 5.7 or 6W and the next LED on the S-meter is starting to flicker
>> > some.
>> >
>> > Moving the power knob will allow me to bring it back to 5.0W, but the
>> > next TUNE will see the power climb back up again.
>> >
>> > I'm not sure if I should still be looking on the RF board at this
>> > point, or start focusing on the control board...?
>> >
>> > Thanks, 73,
>> >
>> > Jeff
>> >
>> > On 4/22/07, Don Wilhelm <w3fpr at earthlink.net> wrote:
>> >> Jeff,
>> >>
>> >> Another thought and a question - does the K2 control power properly
>> >> (check with TUNE) when the requested power is set to 5 watts?  If you
>> >> get somewhere between 4.5 and 5.5 watts output with the requested 
>> power
>> >> set to 5, then the power control circuits are working as they 
>> should be.
>> >>
>> >> Setting the power to maximum will not readily reveal any problems with
>> >> the power control.
>> >>
>> >> OTOH, if the power output is always high then you do have a problem in
>> >> the power control (ALC) loop.
>> >>
>> >> 73,
>> >> Don W3FPR
>> >>
>> >> Jeff Kinzli N6GQ wrote:
>> >> > Don and others,
>> >> >
>> >> > A few weeks back, a user posted about an issue with low power output
>> >> > with his K2. Don said:
>> >> >
>> >> >> If you do not have either the KAT2, the KPA100, or the KAT100
>> >> >> installed, the
>> >> >> K2 does not display the actual power output on the LCD (the 
>> requested
>> >> >> power
>> >> >> is displayed briefly when the power control is changed). What is 
>> the
>> >> >> indication on the LED bargraph during transmit?
>> >> >
>> >> > I'm going through an issue with my K2 where it *appears* to be 
>> putting
>> >> > out too much power. With the KPA100 installed, the output sometimes
>> >> > jumps up to 150+W.
>> >> >
>> >> > I removed the KPA100 from the picture and have been seeing if I can
>> >> > reproduce higher than normal output with just the base K2. So 
>> far, the
>> >> > behavior is that if I enter TUNE mode, the indicated power on the
>> >> > display of the K2 will rise to 16-17W. My watt meter isn't accurate
>> >> > enough to tell me what it's *really* putting out though, although 
>> with
>> >> > the KPA100 it is accurate enough to see the 150W+ peaks.
>> >> >
>> >> > So I was trying to think if it's really putting out 16+W, or if the
>> >> > power meter is really telling me it's TRYING to put it out 
>> (because my
>> >> > external wattmeter looks like actually less, but again not 
>> accurate).
>> >> >
>> >> > I also thought maybe it's an ALC issue, because if I rotate the 
>> power
>> >> > knob back then back up to max, the indicated power on the K2 will go
>> >> > to about 15W, but the next time I do TUNE again, it again goes 
>> back up
>> >> > to 16+W.
>> >> >
>> >> > Any thoughts on this? Should I keep chasing ALC issues? I've already
>> >> > gone through the base K2 RF board resoldering T1-T4, reheating
>> >> > anything that looks suspect, etc. to no avail.
>> >> >
>> >> > I also sent something to this effect to Gary at Support, I'm just 
>> hoping
>> >> > someone might have any ideas that I could chase down.
>> >> >
>> >> > Thanks,
>> >> >
>> >> > Jeff
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