K3 Heat

[rfenabled]

I am now wondering how do you settle on "Normal", "Heavy" and simply "Flat out" to come up with a "design limitation?" From the factory?

Much conjecture and pure guesswork has been written in recent posts as well as some very informative opinions on the cooling system used by Elecraft.

Perhaps we should hear from Elecraft on what design criteria was used when the decision was made to use the existing cooling arrangement.

Does the addition of the KPA-3 and now the 2m option board alter the effectiveness of the cooling system as designed?

Just how *heavy* is heavy?..use or perhaps abuse..?

Feeling around a radio as soon as you power down appears to me to be the same as sticking your fingers on a radiator of a car immediately after switching off. These days a lot of cars run electric fans to allow an even cool down period after running.

To make my point clearer, when I use the ride-on mower for an hour or more, I run the motor for a few minutes after I finish to effect a cooling down of the motor, I do not run my K3 (or any other radio) for RTTY then pull the power, call me cautious perhaps, but it just seems logical to me.

I hope Wayne, Eric and Lyle et al post a response in depth on this topic as many of us have differing points of view.

My two cents worth, or was that a Nickel?

Gary
VK4WT
K3 s/n 679
Sent via BlackBerry® from Telstra
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[dave.wilburn]

The fail temperature of the PA's is going to be well known and
documented.  Then a safety factor is added.  But I seem to recall that
early comments on heat design criteria was for 10m key down, 100% duty
cycle, without damage.  But that is just the memory talking.  YMMV

73

Dave Wilburn
NM4M

[hidden email] wrote:

> I am now wondering how do you settle on "Normal", "Heavy" and simply "Flat out" to come up with a "design limitation?" From the factory?
>
> Much conjecture and pure guesswork has been written in recent posts as well as some very informative opinions on the cooling system used by Elecraft.
>
> Perhaps we should hear from Elecraft on what design criteria was used when the decision was made to use the existing cooling arrangement.
>
> Does the addition of the KPA-3 and now the 2m option board alter the effectiveness of the cooling system as designed?
>
> Just how *heavy* is heavy?..use or perhaps abuse..?
>
> Feeling around a radio as soon as you power down appears to me to be the same as sticking your fingers on a radiator of a car immediately after switching off. These days a lot of cars run electric fans to allow an even cool down period after running.
>
> To make my point clearer, when I use the ride-on mower for an hour or more, I run the motor for a few minutes after I finish to effect a cooling down of the motor, I do not run my K3 (or any other radio) for RTTY then pull the power, call me cautious perhaps, but it just seems logical to me.
>
> I hope Wayne, Eric and Lyle et al post a response in depth on this topic as many of us have differing points of view.
>
> My two cents worth, or was that a Nickel?
>
> Gary
> VK4WT
> K3 s/n 679
> Sent via BlackBerry® from Telstra
> ______________________________________________________________
> 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
>

... [show rest of quote]

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[David Woolley (E.L)]

David Wilburn wrote:
> The fail temperature of the PA's is going to be well known and
> documented. Then a safety factor is added. But I seem to recall that

Things aren't as simple as that.  Mean time between failure tends to
have an inverse exponential relationship with temperature, so any
temperature higher than the minimum possible will compromise lifetime.

Even in terms of the manufacturer's never exceed temperature, this is
specified inside the device, at a point where the thermal time constant
may be quite small, so if you operator too close to TjMax, it may not
need much of a transient to exceed it.

TjMax is typically a round number so is probably significantly less than
the temperature at which the device sustains a phase change (e.g melts),
and exceeding it may simply compromise MTBF.  (It may represent a point
where a lower activation energy failure mode becomes dominant, or may
just represent the point where the manufacturer considers MTBF
unacceptable.)

> early comments on heat design criteria was for 10m key down, 100%
> duty cycle, without damage. But that is just the memory talking. YMMV


--
David Woolley
"The Elecraft list is a forum for the discussion of topics related to
Elecraft products and more general topics related ham radio"
List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm>
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[Guy, K2AV]

WHAT heat problem?

Currently there are over a hundred K3's I know about from all over the
serial number range.  NO burnups, NO burnt hands. Includes one who got up
and left it on TUNE which resulted in NO burned up K3. I'm still asking
about what happened to the dummy load though.  NO KPA3 final failures. And
this from a group of contesters who are notorious abusers of equipment,
including quite some few who run the K3 at 120 watts in contests.

If the K3 was a burn-it-up item with an inherent heat design flaw, like some
other rigs, amps, power supplies, etc, this push-everything-to-the-limits
group would have toasted it by now.  I might have missed one, but I don't
think so.  They DO have a LIST of other rigs, amps, power supplies, etc,
that they HAVE turned into toast. This group is capable of toasting Alphas,
and has.

This group meets once a month just to trade contesting gossip, experience,
yada, yada.  One may be assured that setting a K3 on fire (or any other mode
of heat related destruction) would have been a prime topic.  Telling stories
on others who set things on fire in contests is such fun  : >)

One chapter has an annual "flaming balun" award just for the best of such
delicacies.

It is for sure that Wayne is a lot more concerned about heat than any of
them.

For myself, the K3 has the largest heat sink transfer area I've seen on a
100 watt amplifier in an HF rig. It has by far the beefiest air flow at max
cooling of any HF rig.  And it runs at a very quiet fan speed 1 during most
of my operation.

What heat problem?  No heat problem.

73, Guy.

----- Original Message -----
From: "David Wilburn" <[hidden email]>
To: "Elecraft Discussion List" <[hidden email]>
Sent: Thursday, May 14, 2009 9:00 PM
Subject: Re: [Elecraft] K3 Heat


The fail temperature of the PA's is going to be well known and
documented.  Then a safety factor is added.  But I seem to recall that
early comments on heat design criteria was for 10m key down, 100% duty
cycle, without damage.  But that is just the memory talking.  YMMV

73

Dave Wilburn
NM4M

[hidden email] wrote:

> I am now wondering how do you settle on "Normal", "Heavy" and simply "Flat
> out" to come up with a "design limitation?" From the factory?
>
> Much conjecture and pure guesswork has been written in recent posts as
> well as some very informative opinions on the cooling system used by
> Elecraft.
>
> Perhaps we should hear from Elecraft on what design criteria was used when
> the decision was made to use the existing cooling arrangement.
>
> Does the addition of the KPA-3 and now the 2m option board alter the
> effectiveness of the cooling system as designed?
>
> Just how *heavy* is heavy?..use or perhaps abuse..?
>
> Feeling around a radio as soon as you power down appears to me to be the
> same as sticking your fingers on a radiator of a car immediately after
> switching off. These days a lot of cars run electric fans to allow an even
> cool down period after running.
>
> To make my point clearer, when I use the ride-on mower for an hour or
> more, I run the motor for a few minutes after I finish to effect a cooling
> down of the motor, I do not run my K3 (or any other radio) for RTTY then
> pull the power, call me cautious perhaps, but it just seems logical to me.
>
> I hope Wayne, Eric and Lyle et al post a response in depth on this topic
> as many of us have differing points of view.
>
> My two cents worth, or was that a Nickel?
>
> Gary
> VK4WT
> K3 s/n 679
> Sent via BlackBerry® from Telstra
> ______________________________________________________________
> 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
>

... [show rest of quote]

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[Jim Brown-10]

On Fri, 15 May 2009 10:53:10 -0400, Guy Olinger, K2AV wrote:

>What heat problem?  No heat problem.

Guy said it well. I'm a member of the Northern California Contest
Club, one of the largest. Our members probably own at least 100 K3s.
I own two. My neighbor K6XX owns four, and is a very sharp engineer
who works for Elecraft. He says the the K3 is very well protected,
and that there is no heat problem. Several of our members were early
beta testers. Many of our members, especially those owning K3s, are
very agressive contesters -- that is, we transmit a lot. Some
contests require that we run barefoot, including several RTTY
contests.

W0YK is one of our more agressive members, a world champion RTTY
contester, and an early beta tester. His response to this thread,
before he hurried off to Dayton, was the same as Guy's -- there is
no heat problem. He should know.

73,

Jim Brown K9YC


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[Hisashi T Fujinaka]

On Fri, 15 May 2009, Jim Brown wrote:

> On Fri, 15 May 2009 10:53:10 -0400, Guy Olinger, K2AV wrote:
>
>> What heat problem?  No heat problem.
>
> W0YK is one of our more agressive members, a world champion RTTY
> contester, and an early beta tester. His response to this thread,
> before he hurried off to Dayton, was the same as Guy's -- there is
> no heat problem. He should know.

Well, you're all ignoring the longevity reduction with heat. I'm sure
if you have several K3's, you can afford to replace your rigs quite
often and probably do, but there are guys who are still running their
Drake twins and Collins 75A-3's. And I'm sure that means there are
people who want to run their K3's for as long a time as well.

If this was a K2, I'd say buy spare chassis parts and mount weird fans
to your heart's content. I'm not sure you can do that with a K3.

--
Hisashi T Fujinaka - [hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
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[Rich]

I also have never noticed a problem due to "heat" buildup in the K3. A good cup of coffee is about 140 degrees F or 60 degrees C - well below the failure point and within the "normal" operating limits of most solid state devices. That temperature would leave your fingers red if you placed them on an object that hot, I don’t think you could place your hand on it for more than a brief period of time. I have never felt anything near that warm.  I have never noticed an area on the K3 near the temperature of bath water. Even hot bath water is less than 110 F (43 C) and that is within the "expected" operating temperature of most equipment. It would get hotter than that in your car.

Along the topic of this thread, I built an EICO Kit Stereo amp and tuner while in high school. Now this was a piece of equipment that ran HOT - several areas could burn your hand. While in college I discovered that if I kept my coffee cup on the amp it would keep the coffee warm all evening. That amp and tuner still works today, but I don’t use it for a coffee warmer any more - it must have more than 100,000 hours on it, way beyond expected life expectancy.

Rich,
KE0X

[Jim Brown-10]

On Fri, 15 May 2009 09:14:50 -0700 (PDT), Hisashi T Fujinaka wrote:

>Well, you're all ignoring the longevity reduction with heat.

I'm certainly not, and I doubt that the designers of the radio have
either. K6XX, an engineer who has looked carefully at the design,
considers it very well designed from the point of view of heat and
ventilation. The lead engineer is the same guy who designed the
K2/100. They've sold close to 7,000 of them, and I've never heard
of a problem with heat.

Those who talk about cutting holes to "help" ventilate the radio
are probably forgetting the very well controlled heat flow that has
been established by the design. One side of the radio runs warm
because it is the heat sink for a couple of transistors. The bottom
of the chassis runs warm because it is a heat sink for the driver
transistors. This is very solid EE design. It is NOT indicative of
a problem, or of operation that will cause premature failure.

If you want to be super conservative, set up a small muffin fan to
blow cool air on the radio. And, of course, calibrate the
temperature sensors properly. But don't mess with the design.
There's far more to it than meets the eye, especially the eye of
someone who isn't an EE with this sort of design experience under
his belt.

73,

Jim Brown K9YC


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[Hisashi T Fujinaka]

On Sat, 16 May 2009, Jim Brown wrote:

> On Fri, 15 May 2009 09:14:50 -0700 (PDT), Hisashi T Fujinaka wrote:
>
>> Well, you're all ignoring the longevity reduction with heat.
>
> I'm certainly not, and I doubt that the designers of the radio have
> either. K6XX, an engineer who has looked carefully at the design,
> considers it very well designed from the point of view of heat and
> ventilation. The lead engineer is the same guy who designed the
> K2/100. They've sold close to 7,000 of them, and I've never heard
> of a problem with heat.

Creative snipping, I'm going to do it too.

I was talking about 80-year old radios, and keeping the radio running
for that long. You're talking about 10, maybe?

> If you want to be super conservative, set up a small muffin fan to
> blow cool air on the radio. And, of course, calibrate the
> temperature sensors properly. But don't mess with the design.
> There's far more to it than meets the eye, especially the eye of
> someone who isn't an EE with this sort of design experience under
> his belt.

And that's me, as I did semiconductor design.

I'm just saying, if you want fans, use fans. Let people mess with the
radio if they want. That's why I liked the K2, and one of the reasons I
don't have a K3 yet. (The real reason is that I had to take my antenna
down and so $2k seemed a bit much when I don't have anything to connect
the radio to.)

Also, you said you had several K3's. You're in a whole different league
than people who just have one and want to screw around with it. People
do mods to their FT1000's too, and those rigs are meant to keep their
lids on.

One reason I think screwing around with the radio is good is because
that's how you learn things. Another is that it's fun. Sure you violate
the warranty, but that's the price of admission. I know the designers
made some tradeoffs in this radio; there's no way around that. What's
wrong with second-guessing them and doing experiments as long as you
keep your signal clean and within regulations?

--
Hisashi T Fujinaka - [hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
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[Guy, K2AV]

> Creative snipping, I'm going to do it too.
>
> I was talking about 80-year old radios, and keeping the radio running
> for that long. You're talking about 10, maybe?

Maybe not creative.  Maybe factual?

I have a 56 year old Collins 75A3. And a Johnson Ranger and Viking Courier
just slightly younger, all working. I can assure you that any of them run
half a day will be far warmer above and below the chassis than anywhere
in/on my K3. There is no fan in a 75A3 or Ranger.  There is a fan in the
Courier, but it blows the air off the 811's around inside the box, not
immediately to the outside like the K3.  The heat melted a crayon on top of
a friend's Collins and it dripped down on the chassis. He never got that out
of the paint. Used to keep my coffee warm over the 6146's in the Ranger.

> I'm just saying, if you want fans, use fans. Let people mess with the
> radio if they want. That's why I liked the K2, and one of the reasons I
> don't have a K3 yet.

So you've never actually felt a K3 for heat and fan cooling air movement?

One of the great things about the newer transistor gear vs. the half century
old 18 tube top of line stuff is how COOL (less heat) they are compared to
the classic tube stuff.

My K2/10 gets warmer on the bottom than my K3 gets on the front right side.
I did a full A to B upgrade on it recently and enjoyed every minute of it.
But the K3 is telling me that I have to get VERY technical on really tiny
stuff to mess with it and not make it worse.

We're not saying not to mess with a K3.  It's their property and they can do
whatever. They can measure their K3's chassis strength by throwing it out of
an airplane if they want.

Just pointing out that people are going after a heat problem that doesn't
exist.  And in an era where Google searches fork up all text equally, if it
isn't challenged here, folks just casually reading the reflector will accept
that the K3 has a cooling problem, which it doesn't.

73, Guy.


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[Jim Brown-10]

On Sat, 16 May 2009 15:03:07 -0700 (PDT), Hisashi T Fujinaka wrote:

>Also, you said you had several K3's. You're in a whole different
>league

I'm not sure what that means. I'm a working stiff, but semi-retired.
I'm a contester, so I have two K3s, one with a second RX, so I can
do SO2R.  I sold an MP, an 850, and a K2/100 so I could buy them.

73,

Jim K9YC


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