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Question about K2 power meter

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Jeff Kinzli N6GQ

Question about K2 power meter

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@Support, I'm just hoping
someone might have any ideas that I could chase down.

Thanks,

Jeff
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Don Wilhelm-3

Re: Question about K2 power meter

Jeff,

Is this into an antenna or into a dummy load? If it is into an antenna,
'strange things can happen' in the basic K2 configuration when the
antenna is not 50 ohms pure resistive.

Work into a dummy load first to resolve the situation (or answer your
questions). The LED bargraph should be fairly accurate (but it only
goes up to 10 watts).

If your external wattmeter does not give a good indication at a 5 to 10
watt level, you may find success in measuring the RF voltage across the
dummy load with the RF probe, then calculating the power output from the
voltage (P=V^2/R if your probe reads RF volts RMS - the one provided
with the K2 does read RMS voltage). A high range external wattmeter can
be really far off when indicating lower powers - 20% of the full range
value is a common spec for wattmeter accuracy, and on a 200 watt scale,
that is 40 watts potential error!

Yes, stick with the basic K2 until you can answer the question of how
much power is actually being developed. Once you determine that, you
can chase the cause of the problem if one exists. Don't jump to
conclusions before knowing the answer to this part of the question.

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@Support, I'm just hoping
> someone might have any ideas that I could chase down.
>
> Thanks,
>
> Jeff
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
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> Elecraft web page: http://www.elecraft.com
>
>

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Don Wilhelm-3

Re: Question about K2 power meter

In reply to this post by Jeff Kinzli N6GQ

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:

Jeff Kinzli N6GQ

Re: Question about K2 power meter

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 <[hidden email]> 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@Support, I'm just hoping
> > someone might have any ideas that I could chase down.
> >
> > Thanks,
> >
> > Jeff
> > _______________________________________________
> > Elecraft mailing list
> > Post to: [hidden email]
> > You must be a subscriber to post to the list.
> > Subscriber Info (Addr. Change, sub, unsub etc.):
> > http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/subscribers.htm
> > Elecraft web page: http://www.elecraft.com
> >
> >
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

Don Wilhelm-3

Re: Question about K2 power meter

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 <[hidden email]> 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@Support, I'm just hoping
>> > someone might have any ideas that I could chase down.
>> >
>> > Thanks,
>> >
>> > Jeff
>> > _______________________________________________
>> > Elecraft mailing list
>> > Post to: [hidden email]
>> > You must be a subscriber to post to the list.
>> > Subscriber Info (Addr. Change, sub, unsub etc.):
>> > http://mailman.qth.net/mailman/listinfo/elecraft
>> > Help: http://mailman.qth.net/subscribers.htm
>> > Elecraft web page: http://www.elecraft.com
>> >
>> >
>> _______________________________________________
>> Elecraft mailing list
>> Post to: [hidden email]
>> You must be a subscriber to post to the list.
>> Subscriber Info (Addr. Change, sub, unsub etc.):
>> http://mailman.qth.net/mailman/listinfo/elecraft
>>
>> Help: http://mailman.qth.net/subscribers.htm
>> Elecraft web page: http://www.elecraft.com
>>
>
>

Brett gazdzinski-2

RE: Question about K2 power meter

In reply to this post by Jeff Kinzli N6GQ

Its really confusing, so I recommend ignoring the power out
of the base K2.
The rig seems to measure then correct the power out, with differences
between the tune function and regular key down modes.
The tune function seems to calibrate the regular key down power out...

The K2 measures the power output with a diode and resistor network
off the output, so its looking at only voltage.
Change the impedance or swr slightly and it changes the power out,
and its VERY sensitive to the voltage/swr.
I did some experiments with mine, changing the value of resistors
and changing the load resistance making it about 48 ohms instead of
50, and both changed the power out a lot. Lower the voltage the
diode measures and power output goes up.

>From my tests, I would guess the rig can easily put out over 15
or 20 watts on all bands, but does not because its told not to.

After checking with a dummy load right on the antenna jack, I
found my rig would put out between 15 and 11 watts on all bands,
and the power meter would read a bit high on the higher bands, thus
giving slightly lower power out as the rig THINKS its putting out
more power then it is.

11 or 15 watts on 15 or 10 meters, its not enough to worry about.

I also think the built in antenna tuner helps things, it may be
better at measuring the actual output power or taking into account
the swr or something.

My KPA100 has no problems doing over 120 watts out on all bands
at 13.8 volts or slightly less.

Its output power jumps around some, depending on swr, and the
rig sometimes puts out almost full power
(with or without the KPA100) when first keyed, even if the power
knob is set to a low power.

With the KPA100, you can sometimes watch the power jump from
what its set to up 5 or 10 watts, then back to the correct
value, then down 5 or 10 watts, then back up, over and over.

That does not effect things when sending CW, but people driving amps
with the K2 can have a hard time of it.

I think power output control in the K2 could use some redesign.
I am not sure how commercial rigs do it, but they are generally
stable and smooth in power output.

Brett
N2DTS

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Jeff
> Kinzli N6GQ
> Sent: Sunday, April 22, 2007 11:51 PM
> To: [hidden email]
> Cc: Elecraft Mail Posting
> Subject: Re: [Elecraft] Question about K2 power meter
>
> 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 <[hidden email]> 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@Support, I'm
> just hoping
> > > someone might have any ideas that I could chase down.
> > >
> > > Thanks,
> > >
> > > Jeff
> > > _______________________________________________
> > > Elecraft mailing list
> > > Post to: [hidden email]
> > > You must be a subscriber to post to the list.
> > > Subscriber Info (Addr. Change, sub, unsub etc.):
> > > http://mailman.qth.net/mailman/listinfo/elecraft
> > > Help: http://mailman.qth.net/subscribers.htm
> > > Elecraft web page: http://www.elecraft.com
> > >
> > >
> > _______________________________________________
> > Elecraft mailing list
> > Post to: [hidden email]
> > You must be a subscriber to post to the list.
> > Subscriber Info (Addr. Change, sub, unsub etc.):
> > http://mailman.qth.net/mailman/listinfo/elecraft
> >
> > Help: http://mailman.qth.net/subscribers.htm
> > Elecraft web page: http://www.elecraft.com
> >
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

Jeff Kinzli N6GQ

Re: Question about K2 power meter

In reply to this post by Don Wilhelm-3

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 <[hidden email]> 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 <[hidden email]> 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@Support, I'm just hoping
> >> > someone might have any ideas that I could chase down.
> >> >
> >> > Thanks,
> >> >
> >> > Jeff
> >> > _______________________________________________
> >> > Elecraft mailing list
> >> > Post to: [hidden email]
> >> > You must be a subscriber to post to the list.
> >> > Subscriber Info (Addr. Change, sub, unsub etc.):
> >> > http://mailman.qth.net/mailman/listinfo/elecraft
> >> > Help: http://mailman.qth.net/subscribers.htm
> >> > Elecraft web page: http://www.elecraft.com
> >> >
> >> >
> >> _______________________________________________
> >> Elecraft mailing list
> >> Post to: [hidden email]
> >> You must be a subscriber to post to the list.
> >> Subscriber Info (Addr. Change, sub, unsub etc.):
> >> http://mailman.qth.net/mailman/listinfo/elecraft
> >>
> >> Help: http://mailman.qth.net/subscribers.htm
> >> Elecraft web page: http://www.elecraft.com
> >>
> >
> >
>

Don Wilhelm-3

Re: Question about K2 power meter

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 <[hidden email]> 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 <[hidden email]> 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@Support, I'm just
>> hoping
>> >> > someone might have any ideas that I could chase down.
>> >> >
>> >> > Thanks,
>> >> >
>> >> > Jeff
>> >> > _______________________________________________
>> >> > Elecraft mailing list
>> >> > Post to: [hidden email]
>> >> > You must be a subscriber to post to the list.
>> >> > Subscriber Info (Addr. Change, sub, unsub etc.):
>> >> > http://mailman.qth.net/mailman/listinfo/elecraft
>> >> > Help: http://mailman.qth.net/subscribers.htm
>> >> > Elecraft web page: http://www.elecraft.com
>> >> >
>> >> >
>> >> _______________________________________________
>> >> Elecraft mailing list
>> >> Post to: [hidden email]
>> >> You must be a subscriber to post to the list.
>> >> Subscriber Info (Addr. Change, sub, unsub etc.):
>> >> http://mailman.qth.net/mailman/listinfo/elecraft
>> >>
>> >> Help: http://mailman.qth.net/subscribers.htm
>> >> Elecraft web page: http://www.elecraft.com
>> >>
>> >
>> >
>>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>

Jeff Kinzli N6GQ

Re: Question about K2 power meter

Don, thanks.

I do have a recently-made KPA100 (~3 months) and have installed the
upgraded C31 to combat the parasitic.

When in QSO, I see the power jump up, and it seems to stay there until
I enter a TUNE operation or manually drop the power level via the
power knob.

I spend a lot of time on 40M, so that's where I usually see the
problem. I do believe it happens on other bands though.

If an occasional jump to 150W is ok, then I won't worry about it. I
can leave the power knob lower so that the maximum power reached is
less than 130W on those transients.

73,

Jeff

On 4/23/07, Don Wilhelm <[hidden email]> wrote:

> 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 <[hidden email]> 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 <[hidden email]> 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@Support, I'm just
> >> hoping
> >> >> > someone might have any ideas that I could chase down.
> >> >> >
> >> >> > Thanks,
> >> >> >
> >> >> > Jeff
> >> >> > _______________________________________________
> >> >> > Elecraft mailing list
> >> >> > Post to: [hidden email]
> >> >> > You must be a subscriber to post to the list.
> >> >> > Subscriber Info (Addr. Change, sub, unsub etc.):
> >> >> > http://mailman.qth.net/mailman/listinfo/elecraft
> >> >> > Help: http://mailman.qth.net/subscribers.htm
> >> >> > Elecraft web page: http://www.elecraft.com
> >> >> >
> >> >> >
> >> >> _______________________________________________
> >> >> Elecraft mailing list
> >> >> Post to: [hidden email]
> >> >> You must be a subscriber to post to the list.
> >> >> Subscriber Info (Addr. Change, sub, unsub etc.):
> >> >> http://mailman.qth.net/mailman/listinfo/elecraft
> >> >>
> >> >> Help: http://mailman.qth.net/subscribers.htm
> >> >> Elecraft web page: http://www.elecraft.com
> >> >>
> >> >
> >> >
> >>
> > _______________________________________________
> > Elecraft mailing list
> > Post to: [hidden email]
> > You must be a subscriber to post to the list.
> > Subscriber Info (Addr. Change, sub, unsub etc.):
> > http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/subscribers.htm
> > Elecraft web page: http://www.elecraft.com
> >
> >
>

Don Wilhelm-3

Re: Question about K2 power meter

Jeff,

I was really asking if the power jumped to 160 watts regardless of the
setting of the power control so I could better suggest where the problem
might be - apparently it does not go to 160 watts if you set the power
lower.

That behavior is not normal, and right now I would strongly suspect that
there is a bad solder connection in the KPA100 wattmeter section or in
the VRFDET signal path back to the K2 microprocessor. Do the trimmer
pots R26 and R27 look OK? I have found some that were damaged when
soldering the transformers cores in the PA - a damaged trimmer could
have an intermittent contact at the wiper and cause the results you are
seeing. Check the entire path for FWD power indication from the KPA100
wattmeter to the VRFDET signal output (look at the schematic to identify
the components - and don't forget about the scaling resistors and the
scaling switches Q10 and Q11). Since this is an intermittent condition,
it will be difficult to know when it is fixed - that is what makes
intermittents so hard to deal with - try tapping on things to try to
induce a failure.

73,
Don W3FPR

Jeff Kinzli N6GQ wrote:

> Don, thanks.
>
> I do have a recently-made KPA100 (~3 months) and have installed the
> upgraded C31 to combat the parasitic.
>
> When in QSO, I see the power jump up, and it seems to stay there until
> I enter a TUNE operation or manually drop the power level via the
> power knob.
>
> I spend a lot of time on 40M, so that's where I usually see the
> problem. I do believe it happens on other bands though.
>
> If an occasional jump to 150W is ok, then I won't worry about it. I
> can leave the power knob lower so that the maximum power reached is
> less than 130W on those transients.
>
> 73,
>
> Jeff
>
> On 4/23/07, Don Wilhelm <[hidden email]> wrote:
>> 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 <[hidden email]> 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 <[hidden email]> 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@Support, I'm just
>> >> hoping
>> >> >> > someone might have any ideas that I could chase down.
>> >> >> >
>> >> >> > Thanks,
>> >> >> >
>> >> >> > Jeff
>> >> >> > _______________________________________________
>> >> >> > Elecraft mailing list
>> >> >> > Post to: [hidden email]
>> >> >> > You must be a subscriber to post to the list.
>> >> >> > Subscriber Info (Addr. Change, sub, unsub etc.):
>> >> >> > http://mailman.qth.net/mailman/listinfo/elecraft
>> >> >> > Help: http://mailman.qth.net/subscribers.htm
>> >> >> > Elecraft web page: http://www.elecraft.com
>> >> >> >
>> >> >> >
>> >> >> _______________________________________________
>> >> >> Elecraft mailing list
>> >> >> Post to: [hidden email]
>> >> >> You must be a subscriber to post to the list.
>> >> >> Subscriber Info (Addr. Change, sub, unsub etc.):
>> >> >> http://mailman.qth.net/mailman/listinfo/elecraft
>> >> >>
>> >> >> Help: http://mailman.qth.net/subscribers.htm
>> >> >> Elecraft web page: http://www.elecraft.com
>> >> >>
>> >> >
>> >> >
>> >>
>> > _______________________________________________
>> > Elecraft mailing list
>> > Post to: [hidden email]
>> > You must be a subscriber to post to the list.
>> > Subscriber Info (Addr. Change, sub, unsub etc.):
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Jeff Kinzli N6GQ

Re: Question about K2 power meter

Thanks Don, I'll begin looking...

Jeff

On 4/23/07, Don Wilhelm <[hidden email]> wrote:

> Jeff,
>
> I was really asking if the power jumped to 160 watts regardless of the
> setting of the power control so I could better suggest where the problem
> might be - apparently it does not go to 160 watts if you set the power
> lower.
>
> That behavior is not normal, and right now I would strongly suspect that
> there is a bad solder connection in the KPA100 wattmeter section or in
> the VRFDET signal path back to the K2 microprocessor. Do the trimmer
> pots R26 and R27 look OK? I have found some that were damaged when
> soldering the transformers cores in the PA - a damaged trimmer could
> have an intermittent contact at the wiper and cause the results you are
> seeing. Check the entire path for FWD power indication from the KPA100
> wattmeter to the VRFDET signal output (look at the schematic to identify
> the components - and don't forget about the scaling resistors and the
> scaling switches Q10 and Q11). Since this is an intermittent condition,
> it will be difficult to know when it is fixed - that is what makes
> intermittents so hard to deal with - try tapping on things to try to
> induce a failure.
>
> 73,
> Don W3FPR
>
> Jeff Kinzli N6GQ wrote:
> > Don, thanks.
> >
> > I do have a recently-made KPA100 (~3 months) and have installed the
> > upgraded C31 to combat the parasitic.
> >
> > When in QSO, I see the power jump up, and it seems to stay there until
> > I enter a TUNE operation or manually drop the power level via the
> > power knob.
> >
> > I spend a lot of time on 40M, so that's where I usually see the
> > problem. I do believe it happens on other bands though.
> >
> > If an occasional jump to 150W is ok, then I won't worry about it. I
> > can leave the power knob lower so that the maximum power reached is
> > less than 130W on those transients.
> >
> > 73,
> >
> > Jeff
> >
> > On 4/23/07, Don Wilhelm <[hidden email]> wrote:
> >> 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 <[hidden email]> 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 <[hidden email]> 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@Support, I'm just
> >> >> hoping
> >> >> >> > someone might have any ideas that I could chase down.
> >> >> >> >
> >> >> >> > Thanks,
> >> >> >> >
> >> >> >> > Jeff
> >> >> >> > _______________________________________________
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> >> >> >> >
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> >> >> >
> >> >> >
> >> >>
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>

Vk2NU

Re: Question about K2 power meter

In reply to this post by Jeff Kinzli N6GQ

Just in case anyone else is suffering from unstable power out in tune mode,
I followed Don’s advice (as below) and changed R98 on the RF (270ohm) board
for a 1.5K resistor (I actually had a measured value of 1.64K on the POT but
1.5k was the closest fixed resistor I had).

Now when I enter tune, power output is much more stable, although it still
creeps up slightly with time. This makes tuning my DX-1 a lot easier and I'm
not tripping the amp out! Power out on 10m is down a little on the basic K2
(about 12w max), but I'm still getting 100w with the K2/100..

David, VK2NU

>If the variation is quite bothersome, your K2/100 may be a candidate for
>increasing the value of R98 (on the bottom of the RF Board) to slow down
>The power variation. If you increase it too much, the power output on
>the higher bands may decrease (check that with the basic K2, not with
>the KPA100 powered). In most cases, about 1k is the upper limit for the
>value, but if your K2 has greater gain than the average, you may find
>success with even higher values. It is easiest to substitute a 2k pot
>for R98 when testing for the best value, then measure the pot resistance
>and put in the nearest fixed value resistor.

>This procedure is listed on the Elecraft website - in Builder's
>Resources IIRC.

>73,
>Don W3FPR

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