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KPA500 Heat Expansion Pop

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Joe Word

KPA500 Heat Expansion Pop

My KPA500 has developed a heat expansion pop. When it heats up and
then cools down I get a pop from inside the amp. It does this now
every time I make a SSB transmission.

Anyone else experience this? If so, any resolution?

Joe N9VX
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Rick WA6NHC

Re: KPA500 Heat Expansion Pop

While you're inside the amp, make sure that the transformer is secure and
snug (tighten the bolts if needed, reset the washer and retighten). The
pitch of the pop may be a clue as to what is happening (big thump/tiny pop;
deep/high pitched etc.).

The transformer and amp module are the only two things that should have any
significant heat changes over time. Perhaps run the fan full time to see if
it changes the noise? If so, that would indicate it is the module to me.

Rick WA6NHC

-----Original Message-----
From: Ron D'Eau Claire

I've not heard it.

What gets warm during a transmission is, of course, the RF module heat sink.
The RF module is supported by screws into the heat sink on both sides - one
side going into an aluminum "Z" bracket that runs down the center of the
KPA500 and the other side is secured to the right (looking at the front)
side panel behind the handle.

I'd start by checking all the external case screws (never pass up an
opportunity for an easy fix, Hi!), especially the screws that run across the
center of the top and bottom cover, and the screws behind the handle on the
side. The screws behind the handle thread directly into the RF module heat
sink. The other side of the RF module heat sink is secured to a "Z" bracket
that runs down the center of the KPA500 and is secured to the top and bottom
covers by the screws running down the center of each.

If you built your KPA500 from a kit, you may recall that there are more
screws inside the unit that secure the Z-bracket to the side of the RF
module. Those aren't as easy to get to but could be the source of your
noise.

73, Ron AC7AC

-----Original Message-----

My KPA500 has developed a heat expansion pop. When it heats up and
then cools down I get a pop from inside the amp. It does this now
every time I make a SSB transmission.

Anyone else experience this? If so, any resolution?

Joe N9VX

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Gary Hinson

Re: KPA500 Heat Expansion Pop

In reply to this post by Joe Word

Mine pops or clicks too.

In my case, it sounds like a relay switching. I thought at first it was
something sensing the temperature and changing the fan speed, but the pop
doesn't (often) coincide with a change in fan speed, so I think that's a red
herring.

Another ZL told me his KPA does the same thing.

Our amps still work just fine though!

73
Gary ZL2iFB

> -----Original Message-----
> From: [hidden email] [mailto:elecraft-
> [hidden email]] On Behalf Of Joe Word
> Sent: Friday, 9 December 2011 6:38 a.m.
> To: [hidden email]
> Subject: [Elecraft] KPA500 Heat Expansion Pop
>
> My KPA500 has developed a heat expansion pop. When it heats up and then
> cools down I get a pop from inside the amp. It does this now every time I
> make a SSB transmission.
>
> Anyone else experience this? If so, any resolution?
>
> Joe N9VX
> __________________________________________________________
> ____
> 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

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Joe Word

Re: KPA500 Heat Expansion Pop

In reply to this post by Joe Word

Gary,

That sounds like what I am hearing, thought it was a relay controlling
the fan, but as you said, it did not pop when the fan came on/off.

Joe N9VX

-------------------------------------------------------------------------------------------------------------
Mine pops or clicks too.

In my case, it sounds like a relay switching. I thought at first it was
something sensing the temperature and changing the fan speed, but the pop
doesn't (often) coincide with a change in fan speed, so I think that's a red
herring.

Another ZL told me his KPA does the same thing.

Our amps still work just fine though!

73
Gary ZL2iFB

On Thu, Dec 8, 2011 at 12:37 PM, Joe Word <[hidden email]> wrote:
> My KPA500 has developed a heat expansion pop. When it heats up and
> then cools down I get a pop from inside the amp. It does this now
> every time I make a SSB transmission.
>
> Anyone else experience this? If so, any resolution?
>
> Joe N9VX
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Gary Hinson

Re: KPA500 Heat Expansion Pop

RR

The amp was totally silent for the first few weeks of its life. The clicks
only started happening after a mains brown-out here (the mains went down and
back up several times in rapid succession as they tried to clear a fault in
the local grid, I guess). I wondered if that event might have damaged
something but everything apart from the popper works well.

I tried reloading the firmware* just in case that had been corrupted, but no
change.

The amp only pops when its warm i.e. in use, so it does seem to be
temperature-related.

73
Gary
ZL2iFB

* By the way, I couldn't locate the KPA500 firmware on the Elecraft website
(maybe I overlooked it but I couldn't see a link), but anyway the KPA
Utility found it for me.

> -----Original Message-----
> From: [hidden email] [mailto:elecraft-
> [hidden email]] On Behalf Of Joe Word
> Sent: Friday, 9 December 2011 10:40 a.m.
> To: [hidden email]
> Subject: Re: [Elecraft] KPA500 Heat Expansion Pop
>
> Gary,
>
> That sounds like what I am hearing, thought it was a relay controlling the

fan,
> but as you said, it did not pop when the fan came on/off.
>
> Joe N9VX
>
>
----------------------------------------------------------------------------
------------------
> ---------------
> Mine pops or clicks too.
>
> In my case, it sounds like a relay switching. I thought at first it was
something
> sensing the temperature and changing the fan speed, but the pop doesn't
> (often) coincide with a change in fan speed, so I think that's a red
herring.

>
> Another ZL told me his KPA does the same thing.
>
> Our amps still work just fine though!
>
> 73
> Gary ZL2iFB
>
>
>
> On Thu, Dec 8, 2011 at 12:37 PM, Joe Word <[hidden email]> wrote:
> > My KPA500 has developed a heat expansion pop. When it heats up and
> > then cools down I get a pop from inside the amp. It does this now
> > every time I make a SSB transmission.
> >
> > Anyone else experience this? If so, any resolution?
> >
> > Joe N9VX
> __________________________________________________________
> ____
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

Dave Perry N4QS

Re: KPA500 Heat Expansion Pop

In reply to this post by Joe Word

Yes, my KPA500 has been doing the same. Whenever I mention it here on the
reflector, I get zero response. I cannot tell whether this is a problem or
something that is normal. The pops are very frequent regardless of mode.
Otherwise, the amp appears to function normally.

Dave, N4QS

----- Original Message -----
From: "Joe Word" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, December 08, 2011 11:37 AM
Subject: [Elecraft] KPA500 Heat Expansion Pop

> My KPA500 has developed a heat expansion pop. When it heats up and
> then cools down I get a pop from inside the amp. It does this now
> every time I make a SSB transmission.
>
> Anyone else experience this? If so, any resolution?
>
> Joe N9VX
> ______________________________________________________________
> 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

w0mu

Re: KPA500 Heat Expansion Pop

I have never heard a pop in mine nor in N1NK's in J6.

Mike W0MU

W0MU-1 CC Cluster w0mu.net

On 12/8/2011 5:21 PM, Dave Perry wrote:

> Yes, my KPA500 has been doing the same. Whenever I mention it here on the
> reflector, I get zero response. I cannot tell whether this is a problem or
> something that is normal. The pops are very frequent regardless of mode.
> Otherwise, the amp appears to function normally.
>
> Dave, N4QS
>
> ----- Original Message -----
> From: "Joe Word"<[hidden email]>
> To:<[hidden email]>
> Sent: Thursday, December 08, 2011 11:37 AM
> Subject: [Elecraft] KPA500 Heat Expansion Pop
>
>
>> My KPA500 has developed a heat expansion pop. When it heats up and
>> then cools down I get a pop from inside the amp. It does this now
>> every time I make a SSB transmission.
>>
>> Anyone else experience this? If so, any resolution?
>>
>> Joe N9VX
>> ______________________________________________________________
>> 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

KD2A

Re: KPA500 Heat Expansion Pop

Happens here a lot . Amp doesn't have to warm up much. This symptom also didn't exist when the amp was new but started during long use in contest weekend

N5GE

Re: KPA500 Heat Expansion Pop

In reply to this post by Joe Word

All,

I don't have the noise you describe, but it's logical to me that if the bolt
that goes through the center of the transformer has any slack in it, it might
cause a click or thump when cooling or heating. That may be why Elecraft used
the bell washer under the bolt head to allow expansion and contraction of the
transformer during operation.

Check the nut on the bottom side and see if you can pass a piece of paper
between the bottom reinforcement plate and the nut while the power supply is
cold Don't hold it upside down while you do this. If you can, the nut is not
seated. It's easy to accidentally leave a self locking nut loose, due to the
torque resistance from the locking material in the nut.

Hope that helps.

73,
Tom
Amateur Radio Operator N5GE
ARRL Lifetime Member
QCWA Lifetime Member

"If somebody has a bad heart,
they can plug this jack in at
night as they go to bed and it
will monitor their heart
throughout the night. And the
next morning, when they wake up
dead, there'll be a record."

--Mark S. Fowler, FCC Chairman,
1981 - 1987

On Thu, 8 Dec 2011 12:37:37 -0500, Joe Word <[hidden email]> wrote:

>My KPA500 has developed a heat expansion pop. When it heats up and
>then cools down I get a pop from inside the amp. It does this now
>every time I make a SSB transmission.
>
>Anyone else experience this? If so, any resolution?
>
>Joe N9VX
[snip]

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Amateur Radio Operator N5GE

Iain MacDonnell - N6ML-2

Re: KPA500 Heat Expansion Pop

In reply to this post by Gary Hinson

Same symptoms here ... what sounds like a relay click when warm, but
doesn't appear to correspond to fan speed change, although it often
seemed like there was one click a few seconds after starting to TX
(RTTY), and another click a few seconds after returning to RX.

The firmware is linked at: http://www.elecraft.com/KPA500/kpa500_software.htm

73,

~iain / N6ML

On Thu, Dec 8, 2011 at 3:36 PM, Gary Hinson <[hidden email]> wrote:

> RR
>
> The amp was totally silent for the first few weeks of its life. The clicks
> only started happening after a mains brown-out here (the mains went down and
> back up several times in rapid succession as they tried to clear a fault in
> the local grid, I guess). I wondered if that event might have damaged
> something but everything apart from the popper works well.
>
> I tried reloading the firmware* just in case that had been corrupted, but no
> change.
>
> The amp only pops when its warm i.e. in use, so it does seem to be
> temperature-related.
>
> 73
> Gary
> ZL2iFB
>
> * By the way, I couldn't locate the KPA500 firmware on the Elecraft website
> (maybe I overlooked it but I couldn't see a link), but anyway the KPA
> Utility found it for me.
>
>> -----Original Message-----
>> From: [hidden email] [mailto:elecraft-
>> [hidden email]] On Behalf Of Joe Word
>> Sent: Friday, 9 December 2011 10:40 a.m.
>> To: [hidden email]
>> Subject: Re: [Elecraft] KPA500 Heat Expansion Pop
>>
>> Gary,
>>
>> That sounds like what I am hearing, thought it was a relay controlling the
> fan,
>> but as you said, it did not pop when the fan came on/off.
>>
>> Joe N9VX
>>
>>
> ----------------------------------------------------------------------------
> ------------------
>> ---------------
>> Mine pops or clicks too.
>>
>> In my case, it sounds like a relay switching. I thought at first it was
> something
>> sensing the temperature and changing the fan speed, but the pop doesn't
>> (often) coincide with a change in fan speed, so I think that's a red
> herring.
>>
>> Another ZL told me his KPA does the same thing.
>>
>> Our amps still work just fine though!
>>
>> 73
>> Gary ZL2iFB
>>
>>
>>
>> On Thu, Dec 8, 2011 at 12:37 PM, Joe Word <[hidden email]> wrote:
>> > My KPA500 has developed a heat expansion pop. When it heats up and
>> > then cools down I get a pop from inside the amp. It does this now
>> > every time I make a SSB transmission.
>> >
>> > Anyone else experience this? If so, any resolution?
>> >
>> > Joe N9VX
>> __________________________________________________________
>> ____
>> 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
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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Paul Ormandy ZL4PW

Re: KPA500 Heat Expansion Pop

In reply to this post by Dave Perry N4QS

Hi all,

Also getting the pop here.. I thought it may be a thermal cut-out rather than a relay...
fortunately, it doesn't affect how the KPA500 performs!

Cheers,

Paul

On 9/12/2011 12:21 a.m., Dave Perry wrote:

--

Paul Ormandy, ZL4PW, Oamaru, New Zealand
http://www.zl4pw.orconhosting.net.nz/
www.radiodx.com

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Jeff Cochrane - VK4XA

Re: KPA500 Heat Expansion Pop

In reply to this post by Joe Word

CONTENTS DELETED

The author has deleted this message.

Joe Word

Re: KPA500 Heat Expansion Pop

In reply to this post by Joe Word

This is what I know at this point. Based on comments on this board and
private emails, this is a common issue, I would think a good many
people that don't think they have the issue just don't hear it due to
hearing loss or head phone use. It happens with both factory made and
kits.

I tried to resolve mine by loosening the top panel screws (so not
torqued), but no help.
I loosened the transformer bolt and re-tighten it (it was tight to
start with), but no help.

Could this be from the heat sensing device that triggers the fan?

Joe N9VX

On Thu, Dec 8, 2011 at 12:37 PM, Joe Word <[hidden email]> wrote:
> My KPA500 has developed a heat expansion pop. When it heats up and
> then cools down I get a pop from inside the amp. It does this now
> every time I make a SSB transmission.
>
> Anyone else experience this? If so, any resolution?
>
> Joe N9VX
______________________________________________________________
Elecraft mailing list
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KD2A

Re: KPA500 Heat Expansion Pop

I think I may have solved this problem. One of the other posts mentions that the Z-bracket screws are too long and you don't get a tight fit. I changed the five screws from 5/16" to 3/16" and did notice a better grip between the bracket and the PA assembly. I have run it all evening and haven't heard a click or a pop. I even ran the temp up and still nothing. Will it last? I don't know, but it seems to have fixed it. The guy who suggested this has submitted it to Elecraft for a change. Good luck and lets hear if any of you have the same result.

k6dgw

Re: KPA500 Heat Expansion Pop

Every engineering new grad wants to be the Design Engineer, never
knowing how complex and demanding Product Engineering can be. Nearly 50
email list posts leads to 1/16" change in screw length. I'd be amazed
and stunned, except I've seen it so many times. Count up all the parts
in your radio, multiply by all the possible dimensions that could
matter, and then multiply by all the possible values for those
dimensions [or reverse the order, multiplication is commutative], and
only those who truly understand the magnitude of the National debt can
understand a number that large. And no, I am not a Product Engineer,
nor do I play one on TV. I just have a huge respect for them. When was
the last Nobel awarded to one?

I am amazed that the "Early Elecraft" decided to offer kits, and has
succeeded so well, given all those like me who, given a technological
challenge, cannot fail to screw it up, or so it seems.

Fred K6DGW
Auburn CA
KX1, K2, K3,KPA100, P3, and misc other stuff

On 12/10/2011 4:06 AM, Ron D'Eau Claire wrote:
> The Z bracket should be secure and tight against the side of the heat sink.
> My KPA500 has 5/16" screws and they tighten the Z-bracket so it does not
> move. More recently there have been comments that the 5/16" screws are too
> long, and the length of those screws has now been reduced to 1/4" to ensure
> they don't "bottom out" against the threaded hole in the heat sink before
> they are tight.
>

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