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K2/100 overheating?

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K2/100 overheating?

I recently added the KPA100 to my K2. The heat sink gets VERY hot at any power level above 11 watts (that's when the amp kicks in). The fan is running at high speed and pulling air OUT of the box. Just wondering if this is normal.
Ken/N4KS
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Ken Wagner K3IU

Re: K2/100 overheating?

Have you done the temp calibration?
Check manual about page 49 or so.
73, Ken K3IU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On 5/19/2017 8:01 AM, N4KS via Elecraft
wrote:

> I recently added the KPA100 to my K2. The heat sink gets VERY hot at any power level above 11 watts (that's when the amp kicks in). The fan is running at high speed and pulling air OUT of the box. Just wondering if this is normal.
> Ken/N4KS
> ______________________________________________________________
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Ken Wagner K3IU

Re: K2/100 overheating?

That is the KPA100 manual. Sorry for
possible misdirection.
73, Ken K3IU

On 5/19/2017 8:29 AM, Ken Wagner K3IU wrote:

> Have you done the temp calibration?
> Check manual about page 49 or so.
> 73, Ken K3IU
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> On 5/19/2017 8:01 AM, N4KS via
> Elecraft wrote:
>> I recently added the KPA100 to my K2. The heat sink gets VERY hot at any power level above 11 watts (that's when the amp kicks in). The fan is running at high speed and pulling air OUT of the box. Just wondering if this is normal.
>> Ken/N4KS
>> ______________________________________________________________
>> Elecraft mailing list
>> Home:http://mailman.qth.net/mailman/listinfo/elecraft
>> Help:http://mailman.qth.net/mmfaq.htm
>> Post:mailto:[hidden email]
>>
>> This list hosted by:http://www.qsl.net
>> Please help support this email list:http://www.qsl.net/donate.html
>> Message delivered [hidden email]
>

Don Wilhelm

Re: K2/100 overheating?

In reply to this post by Elecraft mailing list

Ken,

Did you set the bias properly? What is the current draw at 12 watts?
Did you properly balance and calibrate the wattmeter?
Are all the diodes oriented properly? Check against the parts layout
near the back of the manual.

Make certain the fan is mounted with the label out and that the red wire
is in the +hole and the black one in the -hole.
The fan should exhaust the hot air. Cooler air flows in at the front of
the heatsink.

73,
Don W3FPR

On 5/19/2017 8:01 AM, N4KS via Elecraft wrote:
> I recently added the KPA100 to my K2. The heat sink gets VERY hot at any power level above 11 watts (that's when the amp kicks in). The fan is running at high speed and pulling air OUT of the box. Just wondering if this is normal.
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George Winship, NC5G

Re: K2/100 overheating?

Interesting. I built my K2/100 about 17 years ago and the fan has always drawn air into the cabinet and exhausted over the heatsink. So, I rechecked the manual and disassembled my rig to check for proper assembly. Fan label is facing out and wires are soldered to the right pads(red=+, black=-). Was there maybe a change in later models?

73, George

<quote author="Don Wilhelm">
Make certain the fan is mounted with the label out and that the red wire
is in the +hole and the black one in the -hole.
The fan should exhaust the hot air. Cooler air flows in at the front of
the heatsink.

Don Wilhelm

Re: K2/100 overheating?

George,

I will check the fan air flow direction tomorrow because I am uncertain.
If you have the label out and the wires on the correct holes, yours is
likely OK.

There are 2 philosophies about the fan direction. One is that you
should exhaust the heat and let the assembly draw cool air across the
hot components.

The other says to let the fan "blow" on the hot components.
The major difference between the two is that a blower fan adds heat to
the air (due to the work produced by the fan), but adds the benefit of
directing the air flow to the area to be cooled.
An exhaust fan does not add its work product heat to the air being
moved, but the cool air cannot be directed as well because it is spread
over a large area in the enclosure box.

73,
Don W3FPR

On 5/21/2017 11:26 AM, George Winship, NC5G wrote:

> Interesting. I built my K2/100 about 17 years ago and the fan has always
> drawn air into the cabinet and exhausted over the heatsink. So, I rechecked
> the manual and disassembled my rig to check for proper assembly. Fan label
> is facing out and wires are soldered to the right pads(red=+, black=-). Was
> there maybe a change in later models?
>
> 73, George
>
>
>
> Make certain the fan is mounted with the label out and that the red wire
> is in the +hole and the black one in the -hole.
> The fan should exhaust the hot air. Cooler air flows in at the front of
> the heatsink.
>
>
>
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K2-100-overheating-tp7630828p7630883.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Don Wilhelm

Re: K2/100 overheating?

Ron,

My memory of the fan direction may be faulty, and I have responded. I
will check tomorrow.
I have just returned from Dayton (over 500 mile drive), so pardon me if
I am a bit "groggy". I will resolve all that tomorrow.

I did respond to George while I was at Dayton. Yes, there are other
situations that could produce those problems - usually those ate
accociated with the T/R switch area.

73,
Don W3FPR

On 5/21/2017 10:44 PM, Ron D'Eau Claire wrote:

> Don: I guess you never noticed my response to Ken that I posted last Friday.
> The fan moves air INTO the K2, across the PA and it comes out around the
> heat sink fins near the front of the K2, just as George said.
>
> I suggested Ken contact you after he determined that he had in fact set the
> bias current correctly and the fan was operating correctly because you work
> on K2s quite often. It's been five years since mine was apart!
>
> 73, Ron AC7AC
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Don
> Wilhelm
> Sent: Sunday, May 21, 2017 6:19 PM
> To: George Winship, NC5G; [hidden email]
> Subject: Re: [Elecraft] K2/100 overheating?
>
> George,
>
> I will check the fan air flow direction tomorrow because I am uncertain.
> If you have the label out and the wires on the correct holes, yours is
> likely OK.
>
> There are 2 philosophies about the fan direction. One is that you should
> exhaust the heat and let the assembly draw cool air across the hot
> components.
>
> The other says to let the fan "blow" on the hot components.
> The major difference between the two is that a blower fan adds heat to the
> air (due to the work produced by the fan), but adds the benefit of directing
> the air flow to the area to be cooled.
> An exhaust fan does not add its work product heat to the air being moved,
> but the cool air cannot be directed as well because it is spread over a
> large area in the enclosure box.
>
> 73,
> Don W3FPR
>
> On 5/21/2017 11:26 AM, George Winship, NC5G wrote:
>> Interesting. I built my K2/100 about 17 years ago and the fan has always
>> drawn air into the cabinet and exhausted over the heatsink. So, I
> rechecked
>> the manual and disassembled my rig to check for proper assembly. Fan label
>> is facing out and wires are soldered to the right pads(red=+, black=-).
> Was
>> there maybe a change in later models?
>>
>> 73, George
>>
>>
>>
>> Make certain the fan is mounted with the label out and that the red wire
>> is in the +hole and the black one in the -hole.
>> The fan should exhaust the hot air. Cooler air flows in at the front of
>> the heatsink.
>>
>>
>>
>>
>>
>>
>>
>> --
>> View this message in context:
> http://elecraft.365791.n2.nabble.com/K2-100-overheating-tp7630828p7630883.ht
> ml
>> Sent from the Elecraft mailing list archive at Nabble.com.
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
>

Elecraft mailing list

Re: K2/100 overheating?

In reply to this post by Elecraft mailing list

My bias current settings are:
275 mA (power knob set fully CCW)
475 mA (power knob set to 11 watts)
Target 875 mA total (with the 400 mA added per the instructions) In CW test mode, I set bias control R6 to show a reading of 875 mA

Current draw:
12W = 6.6A
40W = 10.0A (note: peaks at 14W then steps down to 12W)
120W with Power set full CW
Checked all of the diodes for proper orientation.

Fan is orientated correctly with label out. my fan pulls the air OUT. There seems to be some confusion regarding the direction of air flow. Others advised it should be pushing air in. With the fan setting in "normal" mode, it goes directly to high speed when it kicks in. I should think it would go to low speed first and then step up to high speed if the temperature increases.
Balanced and calibrated the wattmeter.

I checked Q1 Q2 Q3 Q4 DC voltages in RX and TX. All are good according to the Voltage Chart provided in the manual.
I had to order a new Fan, because of a mistake I made. It should be here by the end of the week. I will provide temperature data when it is reinstalled.
73, Ken N4KSk2/100

--------------------------------------------
On Fri, 5/19/17, Don Wilhelm <[hidden email]> wrote:

Subject: Re: [Elecraft] K2/100 overheating?
To: "N4KS" <[hidden email]>, "[hidden email]" <[hidden email]>
Date: Friday, May 19, 2017, 6:02 PM

Ken,

Did you set the bias properly? What is the
current draw at 12 watts?
Did you properly
balance and calibrate the wattmeter?
Are all
the diodes oriented properly? Check against the parts
layout
near the back of the manual.

Make certain the fan is
mounted with the label out and that the red wire
is in the +hole and the black one in the
-hole.
The fan should exhaust the hot air.
Cooler air flows in at the front of
the
heatsink.

73,
Don W3FPR

On
5/19/2017 8:01 AM, N4KS via Elecraft wrote:
> I recently added the KPA100 to my K2.
The heat sink gets VERY hot at any power level above 11
watts (that's when the amp kicks in). The fan is running
at high speed and pulling air OUT of the box. Just wondering
if this is normal.

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

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Don Wilhelm

Re: K2/100 overheating?

Ken,

That bias setting is correct. The current draw seems a bit high to me,
but may be OK - I do not have typical measurement data.

One more check - make sure that Q6 and Q7 are oriented properly. They
appear at first glance to have 2 flat sides, but the "round side" has
chamfered edges. If those transistors are oriented backwards, they will
cause the KPA100 to oscillate in the 800 to 900 kHz range.

How hot is your definition of hot? There will be heat generated. If you
can hold your hand on the heatsink, it may not be too hot.
The temperature rise should not be much at powers below 20 watts, so if
yours gets hot at those power levels, there is a problem to be found.

You might want to check the diode voltages as well - both in transmit
and receive and at power levels below and above 11 watts. In other
words, check everything listed in the diode voltage chart.

I just checked the fan direction on my older KPA100 - mine pulls air
in. It really does not matter much for cooling purposes in the KPA100.
The fans were changed about a year ago (availability problem, not design
change).
The newer fans may not start on the Hi-Lo setting. You can experiment
with resistors in parallel with R31. I would suggest starting with 1000
ohms and working downward in resistance until the fan starts reliably on
the Low setting (Hi-Lo starts out low and goes to high when the
temperature rises). 1/4 watt resistors will be OK unless the value
necessary goes below 470 ohms, then you should use 1/2 watt.

Make certain the CAL TPA setting in the menu is correct. The actual
setting follows the KPA100 temperature, so let it cool for at least 1/2
hour and set it to the ambient temperature in degC. That will control
when the fan goes to low and when it goes to high.

73,
Don W3FPR

On 5/23/2017 3:17 PM, N4KS wrote:

> My bias current settings are:
> 275 mA (power knob set fully CCW)
> 475 mA (power knob set to 11 watts)
> Target 875 mA total (with the 400 mA added per the instructions) In CW
> test mode, I set bias control R6 to show a reading of 875 mA
>
> Current draw:
> 12W = 6.6A
> 40W = 10.0A (note: peaks at 14W then steps down to 12W)
> 120W with Power set full CW
>
> Checked all of the diodes for proper orientation.
>
> Fan is orientated correctly with label out. my fan pulls the air OUT.
> There seems to be some confusion regarding the direction of air
> flow. Others advised it should be pushing air in. With the fan setting
> in "normal" mode, it goes directly to high speed when it kicks in. I
> should think it would go to low speed first and then step up to high
> speed if the temperature increases.
>
> Balanced and calibrated the wattmeter.
>
> I checked Q1 Q2 Q3 Q4 DC voltages in RX and TX. All are good according
> to the Voltage Chart provided in the manual.
>
> I had to order a new Fan, because of a mistake I made. It should be
> here by the end of the week. I will provide temperature data when it
> is reinstalled.
>
> 73, Ken N4KS
> k2/100
>
> --------------------------------------------
> On Fri, 5/19/17, Don Wilhelm <[hidden email]
> <mailto:[hidden email]>> wrote:
>
> Subject: Re: [Elecraft] K2/100 overheating?
> To: "N4KS" <[hidden email] <mailto:[hidden email]>>,
> "[hidden email] <mailto:[hidden email]>"
> <[hidden email] <mailto:[hidden email]>>
> Date: Friday, May 19, 2017, 6:02 PM
>
> Ken,
>
> Did you set the bias properly? What is the
> current draw at 12 watts?
> Did you properly
> balance and calibrate the wattmeter?
> Are all
> the diodes oriented properly? Check against the parts
> layout
> near the back of the manual.
>
> Make certain the fan is
> mounted with the label out and that the red wire
> is in the +hole and the black one in the
> -hole.
> The fan should exhaust the hot air.
> Cooler air flows in at the front of
> the
> heatsink.
>
> 73,
> Don W3FPR
>
> On
> 5/19/2017 8:01 AM, N4KS via Elecraft wrote:
> > I recently added the KPA100 to my K2.
> The heat sink gets VERY hot at any power level above 11
> watts (that's when the amp kicks in). The fan is running
> at high speed and pulling air OUT of the box. Just wondering
> if this is normal.