KPA500 troubles

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KPA500 troubles

W4GRJ
All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside and smells the
classic something is burning smell. SWR LED's are dancing upwards as it arcs.
KAT500 tuner has the SWR around 1.3:1

I will probably send it off to Elecraft but thought I would ask here for suggestions to
look at before I send it off.

Thanks, Jack
W4GRJ
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Re: KPA500 troubles

efortner
Test it one more time with a 50 ohm dummy load on the output to make sure
you don't have a problem between your antenna and KPA 500 SO239 output
connector.

73, Earl K4KAY

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of W4GRJ
Sent: Monday, October 19, 2015 8:20 AM
To: [hidden email]
Subject: [Elecraft] KPA500 troubles

All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside
and smells the classic something is burning smell. SWR LED's are dancing
upwards as it arcs.
KAT500 tuner has the SWR around 1.3:1

I will probably send it off to Elecraft but thought I would ask here for
suggestions to look at before I send it off.

Thanks, Jack
W4GRJ



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Re: KPA500 troubles

W4GRJ
Good suggestion...I will do that
However, I am running barefoot 100 watts thru the KAT500 with no issues.
Tnx,
Jack
W4GRJ

-----Original Message-----
From: efortner [mailto:[hidden email]]
Sent: Monday, October 19, 2015 8:53 AM
To: 'W4GRJ'; [hidden email]
Subject: RE: [Elecraft] KPA500 troubles

Test it one more time with a 50 ohm dummy load on the output to make sure
you don't have a problem between your antenna and KPA 500 SO239 output
connector.

73, Earl K4KAY

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of W4GRJ
Sent: Monday, October 19, 2015 8:20 AM
To: [hidden email]
Subject: [Elecraft] KPA500 troubles

All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside
and smells the classic something is burning smell. SWR LED's are dancing
upwards as it arcs.
KAT500 tuner has the SWR around 1.3:1

I will probably send it off to Elecraft but thought I would ask here for
suggestions to look at before I send it off.

Thanks, Jack
W4GRJ



--
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Re: KPA500 troubles

Jim Bolit
Power corrupts...........................

Jim

W6AIM



.

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of w4grj
Sent: Monday, October 19, 2015 6:07 AM
To: 'efortner'; [hidden email]
Subject: Re: [Elecraft] KPA500 troubles

Good suggestion...I will do that
However, I am running barefoot 100 watts thru the KAT500 with no issues.
Tnx,
Jack
W4GRJ

-----Original Message-----
From: efortner [mailto:[hidden email]]
Sent: Monday, October 19, 2015 8:53 AM
To: 'W4GRJ'; [hidden email]
Subject: RE: [Elecraft] KPA500 troubles

Test it one more time with a 50 ohm dummy load on the output to make sure
you don't have a problem between your antenna and KPA 500 SO239 output
connector.

73, Earl K4KAY

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of W4GRJ
Sent: Monday, October 19, 2015 8:20 AM
To: [hidden email]
Subject: [Elecraft] KPA500 troubles

All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside
and smells the classic something is burning smell. SWR LED's are dancing
upwards as it arcs.
KAT500 tuner has the SWR around 1.3:1

I will probably send it off to Elecraft but thought I would ask here for
suggestions to look at before I send it off.

Thanks, Jack
W4GRJ



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Re: KPA500 troubles

Elecraft mailing list
In reply to this post by efortner
Yes, but but but if it is arching and burning, be careful!

73, George, K5KG

On 10/19/2015 8:53 AM, efortner wrote:

> Test it one more time with a 50 ohm dummy load on the output to make sure
> you don't have a problem between your antenna and KPA 500 SO239 output
> connector.
>
> 73, Earl K4KAY
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of W4GRJ
> Sent: Monday, October 19, 2015 8:20 AM
> To: [hidden email]
> Subject: [Elecraft] KPA500 troubles
>
> All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside
> and smells the classic something is burning smell. SWR LED's are dancing
> upwards as it arcs.
> KAT500 tuner has the SWR around 1.3:1
>
> I will probably send it off to Elecraft but thought I would ask here for
> suggestions to look at before I send it off.
>
> Thanks, Jack
> W4GRJ
>
>
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/KPA500-troubles-tp7609284.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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--
George Wagner, K5KG
Sarasota, FL
941-400-1960

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Re: KPA500 troubles

Arie Kleingeld PA3A-2
In reply to this post by W4GRJ

Failing pin diode switch ? (not the PIN diode itself, but the
semiconductor switching it)

73
Arie PA3A



Op 19-10-2015 om 14:20 schreef W4GRJ:

> All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside
> and smells the
> classic something is burning smell. SWR LED's are dancing upwards as it
> arcs.
> KAT500 tuner has the SWR around 1.3:1
>
> I will probably send it off to Elecraft but thought I would ask here for
> suggestions to
> look at before I send it off.
>
> Thanks, Jack
> W4GRJ
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/KPA500-troubles-tp7609284.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]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Re: KPA500 troubles

W4GRJ
In reply to this post by W4GRJ
The amp was factory built, about two years old and has worked fine till yesterday.
Anyway talked with Elecraft, the amp is going back. They said there are some updates needed in addition to the repair. I will post the fix when I get it back.
Thanks to all the other replies.
Jack
W4GRJ

On Oct 19, 2015, at 12:27 PM, Ron D'Eau Claire <[hidden email]> wrote:

Jack, did you build the KPA500 yourself? In any case, one point that can
cause trouble is where the hot (center conductor) lead goes to the RF Output
connector. See Figure 40 on page 28 in the kit assembly manual (if you
bought yours built, you can download the manual from the Elecraft web site
(<a href="http://www.elecraft.com/manual/E740149%20KPA500%20Kit%20Assembly%20Manual%2">http://www.elecraft.com/manual/E740149%20KPA500%20Kit%20Assembly%20Manual%2
0Rev%20F4.pdf). That lead needs to be dressed away from the sharp edge of a
shield as shown in the figure to avoid the possibility of an RF arc.

If that's the problem, just move the wire away as described in the manual.

What the KAT500 does not tell you is the SWR on the line between the amp and
the ATU. If it's fairly high you can build up some substantial RF voltages
there.

73, Ron AC7AC

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of W4GRJ
Sent: Monday, October 19, 2015 5:20 AM
To: [hidden email]
Subject: [Elecraft] KPA500 troubles

All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside
and smells the classic something is burning smell. SWR LED's are dancing
upwards as it arcs.
KAT500 tuner has the SWR around 1.3:1

I will probably send it off to Elecraft but thought I would ask here for
suggestions to look at before I send it off.

Thanks, Jack
W4GRJ



--
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http://elecraft.365791.n2.nabble.com/KPA500-troubles-tp7609284.html
Sent from the Elecraft mailing list archive at Nabble.com.
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Re: KPA500 troubles

Petr, OK1RP/M0SIS
In reply to this post by W4GRJ
Hi Jack,

if your KPA500 has LPF board rev. D or earlier then You will need to make LPF TR Switch Rework REV5 modification, Elecraft parts kit: E850607. But maybe there is another issue in your case.

Try to read first then decide. If you want and you have SMD tools then You can try to make this mods first and test if it was the case. If not then you can send to Elecraft service. If you have no SMD tools and experiences then it is better to send it to them now. The people at Elecraft service are great and professional so no worry about.

It is not complicated just a bit tight on the board and not so much space around the parts to remove the old one. Must be done very carefully. I made this mod on KPA500 for two friends already and in both cases amps worked well after that.

Hope it helps.

73 - Petr, OK1RP
73 - Petr, OK1RP
"Apple & Elecraft freak"
B:http://ok1rp.blogspot.com
MeWe: https://bit.ly/2HGPoDx
MeWe: https://bit.ly/2FmwvDt
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Re: KPA500 troubles

Stewart@twinwood
Hi Petr,
I can't find this mod for the KPA500 on the Elecraft site. In fact, I can't find
any KPA500 mods.

Where is it on the web site, please?  I must be looking in the wrong place...

73
Stewart G3RXQ

On Tue, 20 Oct 2015 08:58:17 -0700 (MST), ok1rp wrote:

> Hi Jack,
>
> if your KPA500 has LPF board rev. D or earlier then You will need to make
> LPF TR Switch Rework REV5 modification, Elecraft parts kit: E850607. But
> maybe there is another issue in your case.
>
> Try to read first then decide. If you want and you have SMD tools then You
> can try to make this mods first and test if it was the case. If not then you
> can send to Elecraft service. If you have no SMD tools and experiences then
> it is better to send it to them now. The people at Elecraft service are
> great and professional so no worry about.
>
> It is not complicated just a bit tight on the board and not so much space
> around the parts to remove the old one. Must be done very carefully. I made
> this mod on KPA500 for two friends already and in both cases amps worked
> well after that.
>
> Hope it helps.
>
> 73 - Petr, OK1RP
>
>
> -----
> http://ok1rp.blogspot.com
> --
> View this message in context:
http://elecraft.365791.n2.nabble.com/KPA500-troubles-tp7609284p7609332.html

> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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> 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
> Message delivered to [hidden email]


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Re: KPA500 troubles

Elecraft mailing list
In reply to this post by Petr, OK1RP/M0SIS
Does anyone have a serial number for the changeover?  I don't see
anything on the Elecraft wab page.

Buck
k4ia  K3 #101
Honor Roll 333
8B DXCC

On 10/20/2015 11:58 AM, ok1rp wrote:

> Hi Jack,
>
> if your KPA500 has LPF board rev. D or earlier then You will need to make
> LPF TR Switch Rework REV5 modification, Elecraft parts kit: E850607. But
> maybe there is another issue in your case.
>
> Try to read first then decide. If you want and you have SMD tools then You
> can try to make this mods first and test if it was the case. If not then you
> can send to Elecraft service. If you have no SMD tools and experiences then
> it is better to send it to them now. The people at Elecraft service are
> great and professional so no worry about.
>
> It is not complicated just a bit tight on the board and not so much space
> around the parts to remove the old one. Must be done very carefully. I made
> this mod on KPA500 for two friends already and in both cases amps worked
> well after that.
>
> Hope it helps.
>
> 73 - Petr, OK1RP
>
>
>
> -----
> http://ok1rp.blogspot.com
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/KPA500-troubles-tp7609284p7609332.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
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>
> 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]

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Re: KPA500 troubles

W4GRJ
In reply to this post by Petr, OK1RP/M0SIS
Peter, thanks....amp on it's way to Elecraft.
I will report results when I get it back.
Jack
W4GRJ

On Oct 20, 2015, at 11:58 AM, ok1rp [via Elecraft] <[hidden email]> wrote:

Hi Jack,

if your KPA500 has LPF board rev. D or earlier then You will need to make LPF TR Switch Rework REV5 modification, Elecraft parts kit: E850607. But maybe there is another issue in your case.

Try to read first then decide. If you want and you have SMD tools then You can try to make this mods first and test if it was the case. If not then you can send to Elecraft service. If you have no SMD tools and experiences then it is better to send it to them now. The people at Elecraft service are great and professional so no worry about.

It is not complicated just a bit tight on the board and not so much space around the parts to remove the old one. Must be done very carefully. I made this mod on KPA500 for two friends already and in both cases amps worked well after that.

Hope it helps.

73 - Petr, OK1RP


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Re: KPA500 troubles

mcduffie
In reply to this post by Petr, OK1RP/M0SIS
On Tue, 20 Oct 2015 08:58:17 -0700 (MST), ok1rp wrote:

> if your KPA500 has LPF board rev. D or earlier then You will need to make
> LPF TR Switch Rework REV5 modification, Elecraft parts kit: E850607. But
> maybe there is another issue in your case.

Apparently, I missed the OP on this.  What is it about?  What vintage amp (SN?),
and what does this modification do?

Gary AG0N
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RE: KPA500 troubles

W4GRJ

It has been sent to Elecraft…will advise results when I get it back

SN 1767

 

From: mcduffie [via Elecraft] [mailto:[hidden email]]
Sent: Wednesday, October 21, 2015 10:05 AM
To: W4GRJ
Subject: Re: KPA500 troubles

 

On Tue, 20 Oct 2015 08:58:17 -0700 (MST), ok1rp wrote:

> if your KPA500 has LPF board rev. D or earlier then You will need to make
> LPF TR Switch Rework REV5 modification, Elecraft parts kit: E850607. But
> maybe there is another issue in your case.

Apparently, I missed the OP on this.  What is it about?  What vintage amp (SN?),
and what does this modification do?

Gary AG0N
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RE: KPA500 troubles

W4GRJ
Got the KPA500 back from Elecraft.
Problem found: L22 and other components in the 60M low pass filter circuit burnt through the LPF PCB.
Repair $650 later: Replaced low pass filter module and installed QSK mod.

On the phone I asked what caused the failure, answer was no idea other than component failure.
I understand stuff fails but I thought I would get more than 2 years before a major expensive failure.

Previously had a Ameritron ALS-600 for 5+ years never a problem, sold it to purchase the KPA500.

Sometimes the grass is not greener.

Jack
W4GRJ
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Re: KPA500 troubles

Jim Brown-10
On Wed,11/11/2015 12:10 PM, W4GRJ wrote:
> Got the KPA500 back from Elecraft.
> Problem found: L22 and other components in the 60M low pass filter circuit
> burnt through the LPF PCB.

60M LPF??? Last I looked, the US power limit on 60M is 100W relative to
a half wave dipole.



> Repair $650 later: Replaced low pass filter module and installed QSK mod.
>
> On the phone I asked what caused the failure, answer was no idea other than
> component failure. I understand stuff fails but I thought I would get more than 2 years before a major expensive failure.

The LPF is on the output of the amplifier. One possible cause of failure
could be lightning.

> Previously had a Ameritron ALS-600 for 5+ years never a problem, sold it to
> purchase the KPA500.
>
> Sometimes the grass is not greener.

My only experience with an ALS-600 was at a contest station in PJ4
several years ago. I found it to be a really inferior amp - most of the
time, I was lucky to get 300W out if it. No comparison to a KPA500.

73, Jim K9YC


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Re: KPA500 troubles

David Pratt
Same in the UK, Jim.  Operation on 60m does not require the use of a
KPA500 unless one wants to contravene the terms of one's license.

73 de David G4DMP

In a recent message, Jim Brown <[hidden email]> writes
>On Wed,11/11/2015 12:10 PM, W4GRJ wrote:
>> Got the KPA500 back from Elecraft.
>> Repair $650 later: Replaced low pass filter module and installed QSK mod.
>> Problem found: L22 and other components in the 60M low pass filter circuit
>> burnt through the LPF PCB.
>
>60M LPF??? Last I looked, the US power limit on 60M is 100W relative to
>a half wave dipole.
>

--
  + - - - - - - - - - - - - - - - - +
  | David M Pratt, Kippax, Leeds.   |
  | Website: http://www.g4dmp.co.uk |
  + - - - - - - - - - - - - - - - - +

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Re: KPA500 troubles

Wes (N7WS)
In reply to this post by Jim Brown-10
*§ 97.313 Transmitter power standards*.

"(i) No station may transmit with an effective radiated power (ERP) exceeding
100 W PEP on the 60 m
band. For the purpose of computing ERP, the transmitter PEP will be multiplied
by the antenna gain
relative to a half-wave dipole antenna. A half-wave dipole antenna will be
presumed to have a gain
of 1 (0 dBd). Licensees using other antennas must maintain in their station
records either the antenna
manufacturer’s data on the antenna gain or calculations of the antenna gain."

If I use an inductively-loaded vertical monopole with a minimal ground screen
over Arizona ground my "dBd gain" might well be several dB negative. In which
case, I'm allowed to compensate for that, and line loss, in determining
amplifier output power.  In that, and many other events, a 100W transceiver is
inadequate, ergo, a KPA500 is not out of the question.

Wes, N7WS

On 11/11/2015 1:32 PM, Jim Brown wrote:
> On Wed,11/11/2015 12:10 PM, W4GRJ wrote:
>> Got the KPA500 back from Elecraft.
>> Problem found: L22 and other components in the 60M low pass filter circuit
>> burnt through the LPF PCB.
>
> 60M LPF??? Last I looked, the US power limit on 60M is 100W relative to a half
> wave dipole.
>
>

"(i) No station may transmit with an effective radiated power (ERP) exceeding
100 W PEP on the 60 m
band. For the purpose of computing ERP, the transmitter PEP will be multiplied
by the antenna gain
relative to a half-wave dipole antenna. A half-wave dipole antenna will be
presumed to have a gain
of 1 (0 dBd). Licensees using other antennas must maintain in their station
records either the antenna
manufacturer’s data on the antenna gain or calculations of the antenna gain."

If I use an inductively-loaded vertical monopole with a minimal ground screen
over Arizona ground my "dBd gain" might well be several dB negative.  In which
case, I'm allowed to compensate for that, and line loss, in determining
amplifier output power.  In that, and many other events, a 100W transceiver is
inadequate, ergo, a KPA500 is not out of the question.
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Re: KPA500 troubles

Fred Smith
In reply to this post by Jim Brown-10
The KPA500 is a good small amp I use mine with an IC-9100 most of the time and have not had any real issues with it in 4 yrs. now. For the K3's and K2 I use Alpha amps an 87A and a newer 9500 for HF use. All I can say the brick on the key with forever in the ads they run does say a lot. But it's not till you open up a quality amp like Elecraft or Alpha go you see the real difference.

You can have problems with any product no matter who makes it but at times we bear part of the fault ourselves or like Jim said even lighting might have played a part.

73,
Fred/N0AZZ

Sent from my iPad

> On Nov 11, 2015, at 2:32 PM, Jim Brown <[hidden email]> wrote:
>
>> On Wed,11/11/2015 12:10 PM, W4GRJ wrote:
>> Got the KPA500 back from Elecraft.
>> Problem found: L22 and other components in the 60M low pass filter circuit
>> burnt through the LPF PCB.
>
> 60M LPF??? Last I looked, the US power limit on 60M is 100W relative to a half wave dipole.
>
>
>
>> Repair $650 later: Replaced low pass filter module and installed QSK mod.
>>
>> On the phone I asked what caused the failure, answer was no idea other than
>> component failure. I understand stuff fails but I thought I would get more than 2 years before a major expensive failure.
>
> The LPF is on the output of the amplifier. One possible cause of failure could be lightning.
>
>> Previously had a Ameritron ALS-600 for 5+ years never a problem, sold it to
>> purchase the KPA500.
>>
>> Sometimes the grass is not greener.
>
> My only experience with an ALS-600 was at a contest station in PJ4 several years ago. I found it to be a really inferior amp - most of the time, I was lucky to get 300W out if it. No comparison to a KPA500.
>
> 73, Jim K9YC
>
>
> ______________________________________________________________
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Re: KPA500 troubles

Gary Gregory-2
In reply to this post by David Pratt
Interesting. As a field tester I tried darned hard to break mine, unsuccessfully, guess I failed again.

Sadly, some components do fail, you just have to take it on the chin.

My experience with several MFJ products has not been good, I successfully broke all of them at least once.

It's sometimes just a case of luck, or that chap, what's his name?, oh yeah, Murphy.

73
Gary

-----Original Message-----
From: "David G4DMP" <[hidden email]>
Sent: ‎12/‎11/‎2015 6:58 AM
To: "[hidden email]" <[hidden email]>
Cc: "[hidden email]" <[hidden email]>; "[hidden email]" <[hidden email]>
Subject: Re: [Elecraft] KPA500 troubles

Same in the UK, Jim.  Operation on 60m does not require the use of a
KPA500 unless one wants to contravene the terms of one's license.

73 de David G4DMP

In a recent message, Jim Brown <[hidden email]> writes
>On Wed,11/11/2015 12:10 PM, W4GRJ wrote:
>> Got the KPA500 back from Elecraft.
>> Repair $650 later: Replaced low pass filter module and installed QSK mod.
>> Problem found: L22 and other components in the 60M low pass filter circuit
>> burnt through the LPF PCB.
>
>60M LPF??? Last I looked, the US power limit on 60M is 100W relative to
>a half wave dipole.
>

--
  + - - - - - - - - - - - - - - - - +
  | David M Pratt, Kippax, Leeds.   |
  | Website: http://www.g4dmp.co.uk |
  + - - - - - - - - - - - - - - - - +

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Re: KPA500 troubles

W4GRJ
In reply to this post by Jim Brown-10
Since I have never operated on 60m ever... You figure it out
Jack 
W4GRJ

On Nov 11, 2015, at 3:33 PM, Jim Brown-10 [via Elecraft] <[hidden email]> wrote:

On Wed,11/11/2015 12:10 PM, W4GRJ wrote:
> Got the KPA500 back from Elecraft.
> Problem found: L22 and other components in the 60M low pass filter circuit
> burnt through the LPF PCB.

60M LPF??? Last I looked, the US power limit on 60M is 100W relative to
a half wave dipole.



> Repair $650 later: Replaced low pass filter module and installed QSK mod.
>
> On the phone I asked what caused the failure, answer was no idea other than
> component failure. I understand stuff fails but I thought I would get more than 2 years before a major expensive failure.

The LPF is on the output of the amplifier. One possible cause of failure
could be lightning.

> Previously had a Ameritron ALS-600 for 5+ years never a problem, sold it to
> purchase the KPA500.
>
> Sometimes the grass is not greener.

My only experience with an ALS-600 was at a contest station in PJ4
several years ago. I found it to be a really inferior amp - most of the
time, I was lucky to get 300W out if it. No comparison to a KPA500.

73, Jim K9YC


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