[Elecraft] Question about K2 power meter

[Jeff Kinzli N6GQ]

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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