Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Barry Baines]

Don:

I have the K3-KPA500-KAT500 purchased in August 2014.  Using the Y-Box offered 
by Bob Wilson, N6TV which he configured me, I have the K3 attached to Antenna 
Genius (AG)  Radio Port A with BCD and it works well.  Similarly, I’m using the 
USB interface on the Flex-6700 to provide BCD to the AG on Radio Port B and it 
works well.  

The key advantage of this approach is that I primarily operate remote.  Using 
BCD for both devices means I don’t have to run the AG app on a PC to match the 
antenna port of either radio upon startup of each radio, ensuring that the 
proper antenna for the desired operating band is selected (Tribander or Offset 
Half-wave wire).  Of course, if I want to select a second antenna port for the 
desired band (such as a dummy load), I can still use the AG app to make the 
change.

One thing to point out is that BCD configuration for 160M is different between 
the K3 and AG, so it isn’t possible to select an antenna defined as 160M.  The 
DB-15 pin assignments of the AG and K3 ACC lines for BCD logic also differs.  
As I recall, there is also a voltage level difference between Elecraft and AG 
when using BCD and Bob had to build a circuit within the Y-Box setup to 
compensate for this.  Bob posted an e-mail to this list on 15 SEP 17 describing 
 how he configured the Y-Box to work with AG and still allow the KPA-500, 
KAT-500 to function as intended.

My recommendation for those with a K3 who want to have a BCD connection to an 
Antenna Genius should consider Bob’s Y-Box configuration for AG as an effective 
interface between the two devices.  

FWIW,

Barry Baines, WD4ASW
Keller, TX 

> On Mar 29, 2018, at 12:06 PM, Don Wilhelm  wrote:
> 
> Tony,
> 
> Unless you have a very old K3, the thermal pads should already be in place.  
> Remove the rear bottom panel to see if they are present.
> 
> The thermal conductivity of the pads is the important parameter.  Get the 
> correct thermal pads from Elecraft, they are effective p/n E72 - Adhesive 
> Thermal pads TO220 size.  They are easy to apply.
> 
> 73,
> Don W3FPR
> 
> On 3/29/2018 8:20 AM, N2TK, Tony wrote:
>> Anything special about the thermal pads they recommend or the placement of
>> the pads? Is there anything on the Elecraft site I missed on this?
>> Tnx
>> N2TK, Tony
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Don Wilhelm]

Tony,

Unless you have a very old K3, the thermal pads should already be in 
place.  Remove the rear bottom panel to see if they are present.


The thermal conductivity of the pads is the important parameter.  Get 
the correct thermal pads from Elecraft, they are effective p/n E72 - 
Adhesive Thermal pads TO220 size.  They are easy to apply.


73,
Don W3FPR

On 3/29/2018 8:20 AM, N2TK, Tony wrote:

Anything special about the thermal pads they recommend or the placement of
the pads? Is there anything on the Elecraft site I missed on this?
Tnx
N2TK, Tony


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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Johan Ymerson]

Yes that's my experience to. I get much better IMD at 20W than at 12 W. It 
would be better if the KPA3A, if present, was used for anything above 10W. 

/Johan, SM0XHJ


On Thursday, 29 March 2018 14:39:49 CEST Wes Stewart wrote:
> Doubt that.  From what I've gathered during a lot of TX IMD testing on my
> original K3 and my K3S, with several (lost count) different LPA and HPA
> modules, it's a 10W amp.  It's allowed to go to 12W but that's a really,
> really bad idea, from an IMD standpoint.  IIRC it's been asked that this be
> "fixed" in firmware but it hasn't seemed to be put "on the list."
> 
> Wes  N7WS
> 
>   On 3/29/2018 4:50 AM, hawley, charles j jr wrote:
> > How do we know that’s pushing it? Maybe the LPA is designed for 20 Watts
> > and the K3 cuts them off at 12 Watts.
> > 
> > Chuck Jack
> > KE9UW
> > 
> > Sent from my iPhone, cjack
> > 
> >> On Mar 28, 2018, at 7:23 PM, "j...@kk9a.com"  wrote:
> >> 
> >> Instead of pushing the 12 watt PA this hard it would sure be nice (and
> >> cleaner) to have the option of using the KPA3A for 10-12 watts output.
> >> 
> >> John KK9A
> >> 
> >> 
> >> K7TV wrote:
> >> 
> >> I have been testing sustained power capabilities of wideband HF
> >> transformers for feeding EFHW antennas. This involves running high power
> >> through HF transformers back to back into a dummy load. When running
> >> 200W out of the KPA500, the K3 was indicating 12W, and I think that
> >> means the 100W PA was not operating. After a few minutes the K3 totally
> >> shut down. This had nothing to do with the transformers under test; I
> >> get the same result when running the KPA500 at 200W directly into the
> >> dummy load. After restart the K3 shows no sign of problem unless the
> >> 200W endurance test is run again. Then I increased power just a little
> >> bit so that the 100W stage kicked in. I got 300W out of the KPA500, and
> >> now the K3 keeps going without shutting down. I can see how 12W may be a
> >> bit much for the driver stage, but if so, shouldn't the 100W stage kick
> >> in sooner? Also, I expected the K3/KPA500 combo to be able to produce
> >> any power level I wanted within its range. What I see is that when the
> >> 100W stage kicks in, the output (as seen on an analog meter) makes a big
> >> jump so that certain power levels cannot be achieved.
> >> 
> >> Thanks,
> >> Erik K7TV
> 
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[dgb]

I've blown the LPA's twice running with Ft8 at 12w, with and without 
pads. They do not like 12w for extended times, period ... proceed with 
caution! You can run 11w all day with no problems.


73 Dwight NS9I


On 3/29/2018 7:50 AM, hawley, charles j jr wrote:

How do we know that’s pushing it? Maybe the LPA is designed for 20 Watts and 
the K3 cuts them off at 12 Watts.

Chuck Jack
KE9UW

Sent from my iPhone, cjack


On Mar 28, 2018, at 7:23 PM, "j...@kk9a.com"  wrote:

Instead of pushing the 12 watt PA this hard it would sure be nice (and
cleaner) to have the option of using the KPA3A for 10-12 watts output.

John KK9A


K7TV wrote:

I have been testing sustained power capabilities of wideband HF transformers
for feeding EFHW antennas. This involves running high power through HF
transformers back to back into a dummy load. When running 200W out of the
KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
not operating. After a few minutes the K3 totally shut down. This had
nothing to do with the transformers under test; I get the same result when
running the KPA500 at 200W directly into the dummy load. After restart the
K3 shows no sign of problem unless the 200W endurance test is run again.
Then I increased power just a little bit so that the 100W stage kicked in. I
got 300W out of the KPA500, and now the K3 keeps going without shutting
down. I can see how 12W may be a bit much for the driver stage, but if so,
shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
combo to be able to produce any power level I wanted within its range. What
I see is that when the 100W stage kicks in, the output (as seen on an analog
meter) makes a big jump so that certain power levels cannot be achieved.

Thanks,
Erik K7TV

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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Wes Stewart]

Doubt that.  From what I've gathered during a lot of TX IMD testing on my 
original K3 and my K3S, with several (lost count) different LPA and HPA modules, 
it's a 10W amp.  It's allowed to go to 12W but that's a really, really bad idea, 
from an IMD standpoint.  IIRC it's been asked that this be "fixed" in firmware 
but it hasn't seemed to be put "on the list."


Wes  N7WS

 On 3/29/2018 4:50 AM, hawley, charles j jr wrote:

How do we know that’s pushing it? Maybe the LPA is designed for 20 Watts and 
the K3 cuts them off at 12 Watts.

Chuck Jack
KE9UW

Sent from my iPhone, cjack


On Mar 28, 2018, at 7:23 PM, "j...@kk9a.com"  wrote:

Instead of pushing the 12 watt PA this hard it would sure be nice (and
cleaner) to have the option of using the KPA3A for 10-12 watts output.

John KK9A


K7TV wrote:

I have been testing sustained power capabilities of wideband HF transformers
for feeding EFHW antennas. This involves running high power through HF
transformers back to back into a dummy load. When running 200W out of the
KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
not operating. After a few minutes the K3 totally shut down. This had
nothing to do with the transformers under test; I get the same result when
running the KPA500 at 200W directly into the dummy load. After restart the
K3 shows no sign of problem unless the 200W endurance test is run again.
Then I increased power just a little bit so that the 100W stage kicked in. I
got 300W out of the KPA500, and now the K3 keeps going without shutting
down. I can see how 12W may be a bit much for the driver stage, but if so,
shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
combo to be able to produce any power level I wanted within its range. What
I see is that when the 100W stage kicks in, the output (as seen on an analog
meter) makes a big jump so that certain power levels cannot be achieved.

Thanks,
Erik K7TV



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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[N2TK, Tony]

Anything special about the thermal pads they recommend or the placement of
the pads? Is there anything on the Elecraft site I missed on this?
Tnx
N2TK, Tony  

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Brian Hunt
Sent: Wednesday, March 28, 2018 7:24 PM
To: Elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 powers off when after several minutes of 12W
carrier

For folks who run lots of high duty cycle modes, Elecraft is now
recommending 'thermal pads' between the LPA transistors and the bottom
cover. I found this out when I was doing some mods to my 10yo K3 and the
instructions said to install them and I didn't have 'em. You can get them
from Elecraft, not expensive. 

73,
Brian, K0DTJ
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[hawley, charles j jr]

How do we know that’s pushing it? Maybe the LPA is designed for 20 Watts and 
the K3 cuts them off at 12 Watts.

Chuck Jack 
KE9UW

Sent from my iPhone, cjack 

> On Mar 28, 2018, at 7:23 PM, "j...@kk9a.com"  wrote:
> 
> Instead of pushing the 12 watt PA this hard it would sure be nice (and
> cleaner) to have the option of using the KPA3A for 10-12 watts output.
> 
> John KK9A
> 
> 
> K7TV wrote:
> 
> I have been testing sustained power capabilities of wideband HF transformers
> for feeding EFHW antennas. This involves running high power through HF
> transformers back to back into a dummy load. When running 200W out of the
> KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
> not operating. After a few minutes the K3 totally shut down. This had
> nothing to do with the transformers under test; I get the same result when
> running the KPA500 at 200W directly into the dummy load. After restart the
> K3 shows no sign of problem unless the 200W endurance test is run again.
> Then I increased power just a little bit so that the 100W stage kicked in. I
> got 300W out of the KPA500, and now the K3 keeps going without shutting
> down. I can see how 12W may be a bit much for the driver stage, but if so,
> shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
> combo to be able to produce any power level I wanted within its range. What
> I see is that when the 100W stage kicks in, the output (as seen on an analog
> meter) makes a big jump so that certain power levels cannot be achieved.
> 
> Thanks,
> Erik K7TV
> 
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Erik Basilier]

Brian, thanks for that tip. I bought this K3 used, so I didn't put it
together. Will have to inspect to find out if pads are installed. The serial
# 2241 suggests to me that the pads might indeed be missing.

Recalibrating the wattmeter plus TX gain did not eliminate the problem of
the K3 powering down, and there is still a gap in obtainable output powers.
After recalibration (without the KPA500) the powers not obtainable on 80m
was anything between 12 and 16. I get the impression that this is normal
behavior. Not a problem for normal hamming, and only a minor annoyance when
using the rig as a variable power test instrument. Running the same
endurance test with power setting 12W on 20m did not seem to lead to the rig
shutting down, and the range of unobtainable output powers is actually
between 9 and 12. I attribute this to variations in wattmeter sensitivities
between 80m and 20m. Of course the wattmeter calibration is performed only
on the 20m band.

As I performed the wattmeter calibration today I ran into a complication
that I don't remember from last time I did this (over a year ago). Following
the manual instructions I set the power to 5.0W. (I did this using the power
knob; first I misread it to mean tweak the power setting to obtain a 5W
indication on the external wattmeter. The manual really should not be
ambiguous on this). I brought up the CONFIG:WMTR LP display as instructed. I
then held TUNE to start transmission, and was ready to adjust the main
tuning knob to get 5W on the external meter. However, the transmission did
not utilize the 5W PWR setting. Instead it used the TUN PWR setting, which
happened to be very different. To complete the procedure I had to go back
and adjust TUN PWR to 5W. I must be missing something here...

73,
Erik K7TV



-Original Message-
From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On
Behalf Of Brian Hunt
Sent: Wednesday, March 28, 2018 4:24 PM
To: Elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 powers off when after several minutes of 12W
carrier

For folks who run lots of high duty cycle modes, Elecraft is now
recommending 'thermal pads' between the LPA transistors and the bottom
cover. I found this out when I was doing some mods to my 10yo K3 and the
instructions said to install them and I didn't have 'em. You can get them
from Elecraft, not expensive. 

73,
Brian, K0DTJ
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Brian Hunt]

My K3 is #4113 factory assembled and delivered in April 2010. I'm pretty sure 
the bottom cover had never been off when I did the update mods a couple months 
ago. That's when I asked Elecraft support about it and I assumed it had been 
added to later #s. I've never had any issues but run mostly CW at either 5 
watts or 100 watts. 
73,
Brian, K0DTJ

> On Mar 28, 2018, at 18:02, Mark E. Musick  wrote:
> 
> When I built K3 serial #3505 in September of 2009, the kit had thermal pads
> for the LPA transistors.
> 
> Mark, WB9CIF
> 

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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Mark E. Musick]

When I built K3 serial #3505 in September of 2009, the kit had thermal pads
for the LPA transistors.

Mark, WB9CIF

-Original Message-
From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On
Behalf Of hawley, charles j jr
Sent: Wednesday, March 28, 2018 11:34 PM
To: Brian Hunt <huntin...@coastside.net>
Cc: Elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 powers off when after several minutes of 12W
carrier

So there was a time early on for the K3 when the pads were not installed? I
looked at my 2010 assembly instructions and they required them. So I must
have put them in.

Chuck Jack
KE9UW

Sent from my iPhone, cjack 

> On Mar 28, 2018, at 6:24 PM, Brian Hunt <huntin...@coastside.net> wrote:
> 
> For folks who run lots of high duty cycle modes, Elecraft is now
recommending 'thermal pads' between the LPA transistors and the bottom
cover. I found this out when I was doing some mods to my 10yo K3 and the
instructions said to install them and I didn't have 'em. You can get them
from Elecraft, not expensive. 
> 
> 73,
> Brian, K0DTJ
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[Elecraft] K3 powers off when after several minutes of 12W carrier

[john]

Instead of pushing the 12 watt PA this hard it would sure be nice (and
cleaner) to have the option of using the KPA3A for 10-12 watts output.

John KK9A


K7TV wrote:

I have been testing sustained power capabilities of wideband HF transformers
for feeding EFHW antennas. This involves running high power through HF
transformers back to back into a dummy load. When running 200W out of the
KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
not operating. After a few minutes the K3 totally shut down. This had
nothing to do with the transformers under test; I get the same result when
running the KPA500 at 200W directly into the dummy load. After restart the
K3 shows no sign of problem unless the 200W endurance test is run again.
Then I increased power just a little bit so that the 100W stage kicked in. I
got 300W out of the KPA500, and now the K3 keeps going without shutting
down. I can see how 12W may be a bit much for the driver stage, but if so,
shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
combo to be able to produce any power level I wanted within its range. What
I see is that when the 100W stage kicks in, the output (as seen on an analog
meter) makes a big jump so that certain power levels cannot be achieved.

Thanks,
Erik K7TV

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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Rose]

Any chance of model confusion between K2 and K3?  I recall adding them to
my K2 ... a case of having to hold my tongue just so in order to hold them
and their hardware in place.  Not a place for fat fingers!

73!

K0PP

On Wed, Mar 28, 2018, 17:36 hawley, charles j jr 
wrote:

> So there was a time early on for the K3 when the pads were not installed?
> I looked at my 2010 assembly instructions and they required them. So I must
> have put them in.
>
> Chuck Jack
> KE9UW
>
> Sent from my iPhone, cjack
>
> > On Mar 28, 2018, at 6:24 PM, Brian Hunt  wrote:
> >
> > For folks who run lots of high duty cycle modes, Elecraft is now
> recommending 'thermal pads' between the LPA transistors and the bottom
> cover. I found this out when I was doing some mods to my 10yo K3 and the
> instructions said to install them and I didn't have 'em. You can get them
> from Elecraft, not expensive.
> >
> > 73,
> > Brian, K0DTJ
> > __
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[hawley, charles j jr]

So there was a time early on for the K3 when the pads were not installed? I 
looked at my 2010 assembly instructions and they required them. So I must have 
put them in.

Chuck Jack 
KE9UW

Sent from my iPhone, cjack 

> On Mar 28, 2018, at 6:24 PM, Brian Hunt  wrote:
> 
> For folks who run lots of high duty cycle modes, Elecraft is now recommending 
> 'thermal pads' between the LPA transistors and the bottom cover. I found this 
> out when I was doing some mods to my 10yo K3 and the instructions said to 
> install them and I didn't have 'em. You can get them from Elecraft, not 
> expensive. 
> 
> 73,
> Brian, K0DTJ
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Brian Hunt]

For folks who run lots of high duty cycle modes, Elecraft is now recommending 
'thermal pads' between the LPA transistors and the bottom cover. I found this 
out when I was doing some mods to my 10yo K3 and the instructions said to 
install them and I didn't have 'em. You can get them from Elecraft, not 
expensive. 

73,
Brian, K0DTJ
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Keith Onishi]

My friend had similar problem. It cause was that LPA was not tightly attached 
to K3 bottom cover.
After retighten the screw attaching the LPA to bottom cover, the problem was 
solved.
I hope this helps.

73 de JH3SIF, Keith

> 2018/03/28 13:51、Erik Basilier <ebasil...@cox.net>のメール:
> 
> Same result if the K3 is run at 12W without the KPA500. This is a K3 I
> bought used; I guess I may have forgotten to check the power calibrations on
> it. Will try that next.
> 73,
> Erik K7TV
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On
> Behalf Of Erik Basilier
> Sent: Tuesday, March 27, 2018 9:42 PM
> To: Elecraft@mailman.qth.net
> Subject: [Elecraft] K3 powers off when after several minutes of 12W carrier
> 
> I have been testing sustained power capabilities of wideband HF transformers
> for feeding EFHW antennas. This involves running high power through HF
> transformers back to back into a dummy load. When running 200W out of the
> KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
> not operating. After a few minutes the K3 totally shut down. This had
> nothing to do with the transformers under test; I get the same result when
> running the KPA500 at 200W directly into the dummy load. After restart the
> K3 shows no sign of problem unless the 200W endurance test is run again.
> Then I increased power just a little bit so that the 100W stage kicked in. I
> got 300W out of the KPA500, and now the K3 keeps going without shutting
> down. I can see how 12W may be a bit much for the driver stage, but if so,
> shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
> combo to be able to produce any power level I wanted within its range. What
> I see is that when the 100W stage kicks in, the output (as seen on an analog
> meter) makes a big jump so that certain power levels cannot be achieved.
> 
> Thanks,
> Erik K7TV 
> 
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Re: [Elecraft] K3 powers off when after several minutes of 12W carrier

[Erik Basilier]

Same result if the K3 is run at 12W without the KPA500. This is a K3 I
bought used; I guess I may have forgotten to check the power calibrations on
it. Will try that next.
73,
Erik K7TV

-Original Message-
From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On
Behalf Of Erik Basilier
Sent: Tuesday, March 27, 2018 9:42 PM
To: Elecraft@mailman.qth.net
Subject: [Elecraft] K3 powers off when after several minutes of 12W carrier

I have been testing sustained power capabilities of wideband HF transformers
for feeding EFHW antennas. This involves running high power through HF
transformers back to back into a dummy load. When running 200W out of the
KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
not operating. After a few minutes the K3 totally shut down. This had
nothing to do with the transformers under test; I get the same result when
running the KPA500 at 200W directly into the dummy load. After restart the
K3 shows no sign of problem unless the 200W endurance test is run again.
Then I increased power just a little bit so that the 100W stage kicked in. I
got 300W out of the KPA500, and now the K3 keeps going without shutting
down. I can see how 12W may be a bit much for the driver stage, but if so,
shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
combo to be able to produce any power level I wanted within its range. What
I see is that when the 100W stage kicks in, the output (as seen on an analog
meter) makes a big jump so that certain power levels cannot be achieved.

Thanks,
Erik K7TV 

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[Elecraft] K3 powers off when after several minutes of 12W carrier

[Erik Basilier]

I have been testing sustained power capabilities of wideband HF transformers
for feeding EFHW antennas. This involves running high power through HF
transformers back to back into a dummy load. When running 200W out of the
KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
not operating. After a few minutes the K3 totally shut down. This had
nothing to do with the transformers under test; I get the same result when
running the KPA500 at 200W directly into the dummy load. After restart the
K3 shows no sign of problem unless the 200W endurance test is run again.
Then I increased power just a little bit so that the 100W stage kicked in. I
got 300W out of the KPA500, and now the K3 keeps going without shutting
down. I can see how 12W may be a bit much for the driver stage, but if so,
shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
combo to be able to produce any power level I wanted within its range. What
I see is that when the 100W stage kicks in, the output (as seen on an analog
meter) makes a big jump so that certain power levels cannot be achieved.

Thanks,
Erik K7TV 

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