Elecraft

KPA-1500 input too high

Classic

List

Threaded

13 messages Options

Dave wo2x

KPA-1500 input too high

Hi All,

KPA-1500 s/n 423

Operating 80 meter SSB running 20 watts drive with tuner engaged for about
1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.

Out of nowhere I got an input power too high alarm @ 191 watts! The radio is
capable of 100 watts out max and verified is set to 20 watts.

Set tune power to 10 watts.

Meter in amp during standby reads 10 watts.

Switch to operate and immediately get input power too high alarm @ 91 watts.

Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
approximately 400 watts out with no error.

Any ideas?

Dave wo2x

______________________________________________________________
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

Don Wilhelm

Re: KPA-1500 input too high

What are you using to drive the KPA1500?

Connect the driving transceiver to an external wattmeter, and then to a
dummy load. Do a KeyDown in CW mode and see what the actual power
output is shown on the external wattmeter.

My thinking is that your driving transceiver has lost its ability to
control the power output. Do the test with an external wattmeter and a
dummy load rather than depending on the power indications from either
the KPA1500 or the driving transceiver. In other words, check each
piece of gear one piece at a time.

73,
Don W3FPR

On 4/27/2019 5:48 PM, [hidden email] wrote:

> Hi All,
>
>
>
> KPA-1500 s/n 423
>
>
>
> Operating 80 meter SSB running 20 watts drive with tuner engaged for about
> 1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>
> Out of nowhere I got an input power too high alarm @ 191 watts! The radio is
> capable of 100 watts out max and verified is set to 20 watts.
>
>
>
> Set tune power to 10 watts.
>
> Meter in amp during standby reads 10 watts.
>
> Switch to operate and immediately get input power too high alarm @ 91 watts.
>
>
>
> Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
> approximately 400 watts out with no error.
>
>
>
> Any ideas?
>
>
>
> Dave wo2x
>
>
>
>
>
>
>
> ______________________________________________________________
> 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]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Paul Baldock

Re: KPA-1500 input too high

In reply to this post by Dave wo2x

Try it in to a dummy load.

- Paul

At 02:48 PM 4/27/2019, [hidden email] wrote:

>Hi All,
>
>
>
>KPA-1500 s/n 423
>
>
>
>Operating 80 meter SSB running 20 watts drive with tuner engaged for about
>1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>
>Out of nowhere I got an input power too high alarm @ 191 watts! The radio is
>capable of 100 watts out max and verified is set to 20 watts.
>
>
>
>Set tune power to 10 watts.
>
>Meter in amp during standby reads 10 watts.
>
>Switch to operate and immediately get input power too high alarm @ 91 watts.
>
>
>
>Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>approximately 400 watts out with no error.
>
>
>
>Any ideas?
>
>
>
>Dave wo2x
>
>
>
>
>
>
>
>______________________________________________________________
>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

Dave wo2x

Re: KPA-1500 input too high

In reply to this post by Don Wilhelm

Don, first thing I did. Radio is indeed sending 20 watts on 80 meters. Is a Flex 6600, not capable of 191 watts the amp said it was seeing.

The 3 watt, 3k Ohm resistor on the filter board is discolored and one side desoldered itself. This provides RF to the onboard frequency counter. This is the second time in three months that resistor has been an issue. Last time it was discolored and fell off the board (mounted upside down).

This time it appears to be more involved than just the 3 watt resistor.

Dave wo2x

-----Original Message-----
From: Don Wilhelm <[hidden email]>
Sent: Saturday, April 27, 2019 6:08 PM
To: [hidden email]; [hidden email]
Subject: Re: [Elecraft] KPA-1500 input too high

What are you using to drive the KPA1500?

Connect the driving transceiver to an external wattmeter, and then to a dummy load. Do a KeyDown in CW mode and see what the actual power output is shown on the external wattmeter.

My thinking is that your driving transceiver has lost its ability to control the power output. Do the test with an external wattmeter and a dummy load rather than depending on the power indications from either the KPA1500 or the driving transceiver. In other words, check each piece of gear one piece at a time.

73,
Don W3FPR

On 4/27/2019 5:48 PM, [hidden email] wrote:

Dave wo2x

Re: KPA-1500 input too high

In reply to this post by Paul Baldock

The input too high only happens into a non-resonant load (tuner in circuit).
Also noticed on 20 now when tuner is in operate there is a 3 dB drop in
noise floor.

This is the second time the 3 watt resistor has desoldered itself from the
board and both times the resistor is discolored.

Only one RF path from radios through switching into amp input. Amp output
feeds a 1x4 antenna switch. No other radios transmitting in near proximity.

Definitely something failed on filter board.

Dave wo2x

-----Original Message-----
From: Paul Baldock <[hidden email]>
Sent: Saturday, April 27, 2019 6:21 PM
To: [hidden email]; [hidden email]
Subject: Re: [Elecraft] KPA-1500 input too high

Try it in to a dummy load.

- Paul

At 02:48 PM 4/27/2019, [hidden email] wrote:

>Hi All,
>
>
>
>KPA-1500 s/n 423
>
>
>
>Operating 80 meter SSB running 20 watts drive with tuner engaged for
>about
>1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>
>Out of nowhere I got an input power too high alarm @ 191 watts! The
>radio is capable of 100 watts out max and verified is set to 20 watts.
>
>
>
>Set tune power to 10 watts.
>
>Meter in amp during standby reads 10 watts.
>
>Switch to operate and immediately get input power too high alarm @ 91

watts.

>
>
>
>Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>approximately 400 watts out with no error.
>
>
>
>Any ideas?
>
>
>
>Dave wo2x
>
>
>
>
>
>
>
>______________________________________________________________
>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

Don Wilhelm

Re: KPA-1500 input too high

Dave,

Time to contact [hidden email].
Unfortunately, they are only open for the next 45 minutes (unless
someone is working late), so be patient while the support folks enjoy
their weekend.

73,
Don W3FPR

On 4/27/2019 6:48 PM, [hidden email] wrote:

> The input too high only happens into a non-resonant load (tuner in circuit).
> Also noticed on 20 now when tuner is in operate there is a 3 dB drop in
> noise floor.
>
> This is the second time the 3 watt resistor has desoldered itself from the
> board and both times the resistor is discolored.
>
> Only one RF path from radios through switching into amp input. Amp output
> feeds a 1x4 antenna switch. No other radios transmitting in near proximity.
>
> Definitely something failed on filter board.
>
> Dave wo2x
>
>
> -----Original Message-----
> From: Paul Baldock <[hidden email]>
> Sent: Saturday, April 27, 2019 6:21 PM
> To: [hidden email]; [hidden email]
> Subject: Re: [Elecraft] KPA-1500 input too high
>
> Try it in to a dummy load.
>
> - Paul
>
> At 02:48 PM 4/27/2019, [hidden email] wrote:
>> Hi All,
>>
>>
>>
>> KPA-1500 s/n 423
>>
>>
>>
>> Operating 80 meter SSB running 20 watts drive with tuner engaged for
>> about
>> 1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>>
>> Out of nowhere I got an input power too high alarm @ 191 watts! The
>> radio is capable of 100 watts out max and verified is set to 20 watts.
>>
>>
>>
>> Set tune power to 10 watts.
>>
>> Meter in amp during standby reads 10 watts.
>>
>> Switch to operate and immediately get input power too high alarm @ 91
> watts.
>>
>>
>>
>> Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>> approximately 400 watts out with no error.
>>
>>
>>
>> Any ideas?
>>
>>
>>
>> Dave wo2x
>>
>>
>>
>>
>>
>>
>>
>> ______________________________________________________________
>> 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]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Dave wo2x

Re: KPA-1500 input too high

I can wait until tomorrow. Won’t bother them on Sunday.

The symptom this time is different than last. Last time was amp acting like tuner not tuned. This time showing excessive input power even though actual power is fine.

Let’s see what happens.

Dave wo2x

Sent from my waxed string and tin cans.

> On Apr 27, 2019, at 7:17 PM, Don Wilhelm <[hidden email]> wrote:
>
> Dave,
>
> Time to contact [hidden email].
> Unfortunately, they are only open for the next 45 minutes (unless someone is working late), so be patient while the support folks enjoy their weekend.
>
> 73,
> Don W3FPR
>
>> On 4/27/2019 6:48 PM, [hidden email] wrote:
>> The input too high only happens into a non-resonant load (tuner in circuit).
>> Also noticed on 20 now when tuner is in operate there is a 3 dB drop in
>> noise floor.
>> This is the second time the 3 watt resistor has desoldered itself from the
>> board and both times the resistor is discolored.
>> Only one RF path from radios through switching into amp input. Amp output
>> feeds a 1x4 antenna switch. No other radios transmitting in near proximity.
>> Definitely something failed on filter board.
>> Dave wo2x
>> -----Original Message-----
>> From: Paul Baldock <[hidden email]>
>> Sent: Saturday, April 27, 2019 6:21 PM
>> To: [hidden email]; [hidden email]
>> Subject: Re: [Elecraft] KPA-1500 input too high
>> Try it in to a dummy load.
>> - Paul
>> At 02:48 PM 4/27/2019, [hidden email] wrote:
>>> Hi All,
>>>
>>>
>>>
>>> KPA-1500 s/n 423
>>>
>>>
>>>
>>> Operating 80 meter SSB running 20 watts drive with tuner engaged for
>>> about
>>> 1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>>>
>>> Out of nowhere I got an input power too high alarm @ 191 watts! The
>>> radio is capable of 100 watts out max and verified is set to 20 watts.
>>>
>>>
>>>
>>> Set tune power to 10 watts.
>>>
>>> Meter in amp during standby reads 10 watts.
>>>
>>> Switch to operate and immediately get input power too high alarm @ 91
>> watts.
>>>
>>>
>>>
>>> Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>>> approximately 400 watts out with no error.
>>>
>>>
>>>
>>> Any ideas?
>>>
>>>
>>>
>>> Dave wo2x
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> ______________________________________________________________
>>> 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]
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html

Elecraft mailing list

Re: KPA-1500 input too high

They are going to want to know what is going on with the input power. The burned resistor (twice!) is a very good indication that there is indeed too much power flowing into the KPA’s front end at times. It is quite possible for any transmitter to put out more power than spec at times, especially if it is not properly calibrated.
There are many rigs that as-designed have a bad tendency to overshoot drastically on key-down, then settle to the power they are supposed to be putting out. An analog wattmeter will not be fast enough to show the problem, but the amplifier’s input definitely sees it.

You need to get them to fix the KPA’s input circuit, but you should also investigate your transceiver to find out why it is overshooting at times. Perhaps it is in need of a fresh calibration or something else might be going on.

73!
Jack, W6FB

> On Apr 27, 2019, at 4:20 PM, Dave <[hidden email]> wrote:
>
> I can wait until tomorrow. Won’t bother them on Sunday.
>
> The symptom this time is different than last. Last time was amp acting like tuner not tuned. This time showing excessive input power even though actual power is fine.
>
> Let’s see what happens.
>
> Dave wo2x
>
> Sent from my waxed string and tin cans.
>
>> On Apr 27, 2019, at 7:17 PM, Don Wilhelm <[hidden email]> wrote:
>>
>> Dave,
>>
>> Time to contact [hidden email].
>> Unfortunately, they are only open for the next 45 minutes (unless someone is working late), so be patient while the support folks enjoy their weekend.
>>
>> 73,
>> Don W3FPR
>>
>>> On 4/27/2019 6:48 PM, [hidden email] wrote:
>>> The input too high only happens into a non-resonant load (tuner in circuit).
>>> Also noticed on 20 now when tuner is in operate there is a 3 dB drop in
>>> noise floor.
>>> This is the second time the 3 watt resistor has desoldered itself from the
>>> board and both times the resistor is discolored.
>>> Only one RF path from radios through switching into amp input. Amp output
>>> feeds a 1x4 antenna switch. No other radios transmitting in near proximity.
>>> Definitely something failed on filter board.
>>> Dave wo2x
>>> -----Original Message-----
>>> From: Paul Baldock <[hidden email]>
>>> Sent: Saturday, April 27, 2019 6:21 PM
>>> To: [hidden email]; [hidden email]
>>> Subject: Re: [Elecraft] KPA-1500 input too high
>>> Try it in to a dummy load.
>>> - Paul
>>> At 02:48 PM 4/27/2019, [hidden email] wrote:
>>>> Hi All,
>>>>
>>>>
>>>>
>>>> KPA-1500 s/n 423
>>>>
>>>>
>>>>
>>>> Operating 80 meter SSB running 20 watts drive with tuner engaged for
>>>> about
>>>> 1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>>>>
>>>> Out of nowhere I got an input power too high alarm @ 191 watts! The
>>>> radio is capable of 100 watts out max and verified is set to 20 watts.
>>>>
>>>>
>>>>
>>>> Set tune power to 10 watts.
>>>>
>>>> Meter in amp during standby reads 10 watts.
>>>>
>>>> Switch to operate and immediately get input power too high alarm @ 91
>>> watts.
>>>>
>>>>
>>>>
>>>> Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>>>> approximately 400 watts out with no error.
>>>>
>>>>
>>>>
>>>> Any ideas?
>>>>
>>>>
>>>>
>>>> Dave wo2x
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ______________________________________________________________
>>>> 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]
>>> 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]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Dave wo2x

Re: KPA-1500 input too high

Hi Jack,

No indication suggests the radio is putting out excessive power. To prove the point I used two different radios (Flex 6600 and Anan 7000dle. Anan has PA power calibrated.)

Flex Power Genius XL has lightning fast protection and never shows spikes. Array Solutions Power Master II does not show spikes. It is NOT a spike issue but rather the amp thinks input power is excessive. It thinks 10 watts is 79 and 21 watts is 191.

Something is amiss when using the amp on 80 meters with tuner in circuit. Remote app says max power of 1620 but I run about 1250 max. All other bands are resonant.

Another symptom is when going from standby to operate the noise floor drops 3 dB on bands where the tuner is bypassed.

The 3 watt resistor was added after initial design of Rev C filter board. It is in the circuit that feeds RF to the on board frequency counter. This is on the input side of the filter board. Maximum power I run on any band is 35 watts.

I am sure when the log file is reviewed it will show it is not spikes.

Dave wo2x

Sent from my iPad

> On Apr 27, 2019, at 8:28 PM, Jack Brindle <[hidden email]> wrote:
>
> They are going to want to know what is going on with the input power. The burned resistor (twice!) is a very good indication that there is indeed too much power flowing into the KPA’s front end at times. It is quite possible for any transmitter to put out more power than spec at times, especially if it is not properly calibrated.
> There are many rigs that as-designed have a bad tendency to overshoot drastically on key-down, then settle to the power they are supposed to be putting out. An analog wattmeter will not be fast enough to show the problem, but the amplifier’s input definitely sees it.
>
> You need to get them to fix the KPA’s input circuit, but you should also investigate your transceiver to find out why it is overshooting at times. Perhaps it is in need of a fresh calibration or something else might be going on.
>
> 73!
> Jack, W6FB
>
>
>
>> On Apr 27, 2019, at 4:20 PM, Dave <[hidden email]> wrote:
>>
>> I can wait until tomorrow. Won’t bother them on Sunday.
>>
>> The symptom this time is different than last. Last time was amp acting like tuner not tuned. This time showing excessive input power even though actual power is fine.
>>
>> Let’s see what happens.
>>
>> Dave wo2x
>>
>> Sent from my waxed string and tin cans.
>>
>>> On Apr 27, 2019, at 7:17 PM, Don Wilhelm <[hidden email]> wrote:
>>>
>>> Dave,
>>>
>>> Time to contact [hidden email].
>>> Unfortunately, they are only open for the next 45 minutes (unless someone is working late), so be patient while the support folks enjoy their weekend.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>>> On 4/27/2019 6:48 PM, [hidden email] wrote:
>>>> The input too high only happens into a non-resonant load (tuner in circuit).
>>>> Also noticed on 20 now when tuner is in operate there is a 3 dB drop in
>>>> noise floor.
>>>> This is the second time the 3 watt resistor has desoldered itself from the
>>>> board and both times the resistor is discolored.
>>>> Only one RF path from radios through switching into amp input. Amp output
>>>> feeds a 1x4 antenna switch. No other radios transmitting in near proximity.
>>>> Definitely something failed on filter board.
>>>> Dave wo2x
>>>> -----Original Message-----
>>>> From: Paul Baldock <[hidden email]>
>>>> Sent: Saturday, April 27, 2019 6:21 PM
>>>> To: [hidden email]; [hidden email]
>>>> Subject: Re: [Elecraft] KPA-1500 input too high
>>>> Try it in to a dummy load.
>>>> - Paul
>>>> At 02:48 PM 4/27/2019, [hidden email] wrote:
>>>>> Hi All,
>>>>>
>>>>>
>>>>>
>>>>> KPA-1500 s/n 423
>>>>>
>>>>>
>>>>>
>>>>> Operating 80 meter SSB running 20 watts drive with tuner engaged for
>>>>> about
>>>>> 1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>>>>>
>>>>> Out of nowhere I got an input power too high alarm @ 191 watts! The
>>>>> radio is capable of 100 watts out max and verified is set to 20 watts.
>>>>>
>>>>>
>>>>>
>>>>> Set tune power to 10 watts.
>>>>>
>>>>> Meter in amp during standby reads 10 watts.
>>>>>
>>>>> Switch to operate and immediately get input power too high alarm @ 91
>>>> watts.
>>>>>
>>>>>
>>>>>
>>>>> Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>>>>> approximately 400 watts out with no error.
>>>>>
>>>>>
>>>>>
>>>>> Any ideas?
>>>>>
>>>>>
>>>>>
>>>>> Dave wo2x
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ______________________________________________________________
>>>>> 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]
>>>> 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]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>

Elecraft mailing list

Re: KPA-1500 input too high

Components fail for a reason, which almost always is because they have been over-stressed. Component manufacturers spend a lot of time analyzing their devices to determine their stress points, failure modes and safe usage areas. When we design equipment, we look at this information to make sure the component will perform exactly the way we need it to perform for the lifetime of the design, and that we do not stress the component so as to make sure that it remains in the safe zone. This is done for each and every component in the design. In some cases, such as high availability systems (think telephone switches and other mission-critical devices) the work is required by the customer in contracts, in others it is done to reduce the failure opportunities and thus the need for repairs. The arena of six-sigma design was created to directly address component design and reduce opportunities for failure.

When approaching a failure of this sort, you have to ask why the component failed. It didn’t fail on its own, there was some stress that caused it to fail. Resistor stresses are very well known. When they fail with an over-heating indication (burn marks, etc), then the over-stress has to be questioned. You can bet that it comes from having too much drive into the equipment. At that point, you then need to ask where that drive came from, then start looking at everything in the overall system for the reason. You will most likely be surprised where it comes from. The fact that this has happened twice is an excellent indicator that it is somewhere in the system that has yet to be properly investigated. I would encourage you to better look into the components to find out just what is going on. To put it another way, I have reviewed enough KPA500 log files for this scenario to have an excellent feel for where these problems arise. It is never the amplifier.

Good luck with your station. I hope you find the issue without too much difficulty.

73,
Jack, W6FB

> On Apr 27, 2019, at 5:48 PM, Dave <[hidden email]> wrote:
>
> Hi Jack,
>
> No indication suggests the radio is putting out excessive power. To prove the point I used two different radios (Flex 6600 and Anan 7000dle. Anan has PA power calibrated.)
>
> Flex Power Genius XL has lightning fast protection and never shows spikes. Array Solutions Power Master II does not show spikes. It is NOT a spike issue but rather the amp thinks input power is excessive. It thinks 10 watts is 79 and 21 watts is 191.
>
> Something is amiss when using the amp on 80 meters with tuner in circuit. Remote app says max power of 1620 but I run about 1250 max. All other bands are resonant.
>
> Another symptom is when going from standby to operate the noise floor drops 3 dB on bands where the tuner is bypassed.
>
> The 3 watt resistor was added after initial design of Rev C filter board. It is in the circuit that feeds RF to the on board frequency counter. This is on the input side of the filter board. Maximum power I run on any band is 35 watts.
>
> I am sure when the log file is reviewed it will show it is not spikes.
>
> Dave wo2x
>
> Sent from my iPad
>
>> On Apr 27, 2019, at 8:28 PM, Jack Brindle <[hidden email]> wrote:
>>
>> They are going to want to know what is going on with the input power. The burned resistor (twice!) is a very good indication that there is indeed too much power flowing into the KPA’s front end at times. It is quite possible for any transmitter to put out more power than spec at times, especially if it is not properly calibrated.
>> There are many rigs that as-designed have a bad tendency to overshoot drastically on key-down, then settle to the power they are supposed to be putting out. An analog wattmeter will not be fast enough to show the problem, but the amplifier’s input definitely sees it.
>>
>> You need to get them to fix the KPA’s input circuit, but you should also investigate your transceiver to find out why it is overshooting at times. Perhaps it is in need of a fresh calibration or something else might be going on.
>>
>> 73!
>> Jack, W6FB
>>
>>
>>
>>> On Apr 27, 2019, at 4:20 PM, Dave <[hidden email]> wrote:
>>>
>>> I can wait until tomorrow. Won’t bother them on Sunday.
>>>
>>> The symptom this time is different than last. Last time was amp acting like tuner not tuned. This time showing excessive input power even though actual power is fine.
>>>
>>> Let’s see what happens.
>>>
>>> Dave wo2x
>>>
>>> Sent from my waxed string and tin cans.
>>>
>>>> On Apr 27, 2019, at 7:17 PM, Don Wilhelm <[hidden email]> wrote:
>>>>
>>>> Dave,
>>>>
>>>> Time to contact [hidden email].
>>>> Unfortunately, they are only open for the next 45 minutes (unless someone is working late), so be patient while the support folks enjoy their weekend.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
>>>>> On 4/27/2019 6:48 PM, [hidden email] wrote:
>>>>> The input too high only happens into a non-resonant load (tuner in circuit).
>>>>> Also noticed on 20 now when tuner is in operate there is a 3 dB drop in
>>>>> noise floor.
>>>>> This is the second time the 3 watt resistor has desoldered itself from the
>>>>> board and both times the resistor is discolored.
>>>>> Only one RF path from radios through switching into amp input. Amp output
>>>>> feeds a 1x4 antenna switch. No other radios transmitting in near proximity.
>>>>> Definitely something failed on filter board.
>>>>> Dave wo2x
>>>>> -----Original Message-----
>>>>> From: Paul Baldock <[hidden email]>
>>>>> Sent: Saturday, April 27, 2019 6:21 PM
>>>>> To: [hidden email]; [hidden email]
>>>>> Subject: Re: [Elecraft] KPA-1500 input too high
>>>>> Try it in to a dummy load.
>>>>> - Paul
>>>>> At 02:48 PM 4/27/2019, [hidden email] wrote:
>>>>>> Hi All,
>>>>>>
>>>>>>
>>>>>>
>>>>>> KPA-1500 s/n 423
>>>>>>
>>>>>>
>>>>>>
>>>>>> Operating 80 meter SSB running 20 watts drive with tuner engaged for
>>>>>> about
>>>>>> 1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>>>>>>
>>>>>> Out of nowhere I got an input power too high alarm @ 191 watts! The
>>>>>> radio is capable of 100 watts out max and verified is set to 20 watts.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Set tune power to 10 watts.
>>>>>>
>>>>>> Meter in amp during standby reads 10 watts.
>>>>>>
>>>>>> Switch to operate and immediately get input power too high alarm @ 91
>>>>> watts.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>>>>>> approximately 400 watts out with no error.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Any ideas?
>>>>>>
>>>>>>
>>>>>>
>>>>>> Dave wo2x
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ______________________________________________________________
>>>>>> 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]
>>>>> 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]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>

Dave wo2x

Re: KPA-1500 input too high

I agree the root cause needs to be identified but my point is in standby power always reads correct. In operate on 80 with tuner in circuit everything is ok also until the failure.

Once something failed the amp is now reporting incorrectly that there is excessive input power. Wheter output power somehow is being coupled back into the input detection circuit or a failure of the circuit misreporting input power is still to be determined.

I find it near impossible that a Flex 6600 can have a forward spike of 191 watts when output set to 22 watts and go undetected since the radio is new. I also find a totally different radio also shows forward power alarm of 188 watts when also set to 22 watts.

This is clearly a failure of the amplifier causing it to misreport input power when in operate. There is also the issue of excessive power flowing through th3 3k Ohm 3 watt resistor that feeds the onboard frequency counter. Not sure why this is happening as I do not overdrive the amp and log files back that up.

I think that the reactance of my 80 meter antenna (optimized G5RV) may be too much for the amp & tuner. The remote app sjows max power of 1620 watts and I run 1250 PEP.

Maybe I should dump the KPA1500 and stick with the Power Genius XL, which by the way is working perfectly with an HF Auto in place of the KPA1500. No power spikes seen on the amp, tuner, or Power Master II.

I do appreciate you suggesting to check everything (radio, antenna, etc). Makes sense but this is a straight up amp failure.

Now to determine what conditions caused the failure.

P.S. - I kmow about Six Sigma, having worked 17 years for Motorola.

Dave wo2x

Sent from my iPad

> On Apr 28, 2019, at 4:22 PM, Jack Brindle <[hidden email]> wrote:
>
> Components fail for a reason, which almost always is because they have been over-stressed. Component manufacturers spend a lot of time analyzing their devices to determine their stress points, failure modes and safe usage areas. When we design equipment, we look at this information to make sure the component will perform exactly the way we need it to perform for the lifetime of the design, and that we do not stress the component so as to make sure that it remains in the safe zone. This is done for each and every component in the design. In some cases, such as high availability systems (think telephone switches and other mission-critical devices) the work is required by the customer in contracts, in others it is done to reduce the failure opportunities and thus the need for repairs. The arena of six-sigma design was created to directly address component design and reduce opportunities for failure.
>
> When approaching a failure of this sort, you have to ask why the component failed. It didn’t fail on its own, there was some stress that caused it to fail. Resistor stresses are very well known. When they fail with an over-heating indication (burn marks, etc), then the over-stress has to be questioned. You can bet that it comes from having too much drive into the equipment. At that point, you then need to ask where that drive came from, then start looking at everything in the overall system for the reason. You will most likely be surprised where it comes from. The fact that this has happened twice is an excellent indicator that it is somewhere in the system that has yet to be properly investigated. I would encourage you to better look into the components to find out just what is going on. To put it another way, I have reviewed enough KPA500 log files for this scenario to have an excellent feel for where these problems arise. It is never the amplifier.
>
> Good luck with your station. I hope you find the issue without too much difficulty.
>
> 73,
> Jack, W6FB
>
>> On Apr 27, 2019, at 5:48 PM, Dave <[hidden email]> wrote:
>>
>> Hi Jack,
>>
>> No indication suggests the radio is putting out excessive power. To prove the point I used two different radios (Flex 6600 and Anan 7000dle. Anan has PA power calibrated.)
>>
>> Flex Power Genius XL has lightning fast protection and never shows spikes. Array Solutions Power Master II does not show spikes. It is NOT a spike issue but rather the amp thinks input power is excessive. It thinks 10 watts is 79 and 21 watts is 191.
>>
>> Something is amiss when using the amp on 80 meters with tuner in circuit. Remote app says max power of 1620 but I run about 1250 max. All other bands are resonant.
>>
>> Another symptom is when going from standby to operate the noise floor drops 3 dB on bands where the tuner is bypassed.
>>
>> The 3 watt resistor was added after initial design of Rev C filter board. It is in the circuit that feeds RF to the on board frequency counter. This is on the input side of the filter board. Maximum power I run on any band is 35 watts.
>>
>> I am sure when the log file is reviewed it will show it is not spikes.
>>
>> Dave wo2x
>>
>> Sent from my iPad
>>
>>> On Apr 27, 2019, at 8:28 PM, Jack Brindle <[hidden email]> wrote:
>>>
>>> They are going to want to know what is going on with the input power. The burned resistor (twice!) is a very good indication that there is indeed too much power flowing into the KPA’s front end at times. It is quite possible for any transmitter to put out more power than spec at times, especially if it is not properly calibrated.
>>> There are many rigs that as-designed have a bad tendency to overshoot drastically on key-down, then settle to the power they are supposed to be putting out. An analog wattmeter will not be fast enough to show the problem, but the amplifier’s input definitely sees it.
>>>
>>> You need to get them to fix the KPA’s input circuit, but you should also investigate your transceiver to find out why it is overshooting at times. Perhaps it is in need of a fresh calibration or something else might be going on.
>>>
>>> 73!
>>> Jack, W6FB
>>>
>>>
>>>
>>>> On Apr 27, 2019, at 4:20 PM, Dave <[hidden email]> wrote:
>>>>
>>>> I can wait until tomorrow. Won’t bother them on Sunday.
>>>>
>>>> The symptom this time is different than last. Last time was amp acting like tuner not tuned. This time showing excessive input power even though actual power is fine.
>>>>
>>>> Let’s see what happens.
>>>>
>>>> Dave wo2x
>>>>
>>>> Sent from my waxed string and tin cans.
>>>>
>>>>> On Apr 27, 2019, at 7:17 PM, Don Wilhelm <[hidden email]> wrote:
>>>>>
>>>>> Dave,
>>>>>
>>>>> Time to contact [hidden email].
>>>>> Unfortunately, they are only open for the next 45 minutes (unless someone is working late), so be patient while the support folks enjoy their weekend.
>>>>>
>>>>> 73,
>>>>> Don W3FPR
>>>>>
>>>>>> On 4/27/2019 6:48 PM, [hidden email] wrote:
>>>>>> The input too high only happens into a non-resonant load (tuner in circuit).
>>>>>> Also noticed on 20 now when tuner is in operate there is a 3 dB drop in
>>>>>> noise floor.
>>>>>> This is the second time the 3 watt resistor has desoldered itself from the
>>>>>> board and both times the resistor is discolored.
>>>>>> Only one RF path from radios through switching into amp input. Amp output
>>>>>> feeds a 1x4 antenna switch. No other radios transmitting in near proximity.
>>>>>> Definitely something failed on filter board.
>>>>>> Dave wo2x
>>>>>> -----Original Message-----
>>>>>> From: Paul Baldock <[hidden email]>
>>>>>> Sent: Saturday, April 27, 2019 6:21 PM
>>>>>> To: [hidden email]; [hidden email]
>>>>>> Subject: Re: [Elecraft] KPA-1500 input too high
>>>>>> Try it in to a dummy load.
>>>>>> - Paul
>>>>>> At 02:48 PM 4/27/2019, [hidden email] wrote:
>>>>>>> Hi All,
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> KPA-1500 s/n 423
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Operating 80 meter SSB running 20 watts drive with tuner engaged for
>>>>>>> about
>>>>>>> 1240 watts out PEP. Remote app shows maximum power handling of 1620 watts.
>>>>>>>
>>>>>>> Out of nowhere I got an input power too high alarm @ 191 watts! The
>>>>>>> radio is capable of 100 watts out max and verified is set to 20 watts.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Set tune power to 10 watts.
>>>>>>>
>>>>>>> Meter in amp during standby reads 10 watts.
>>>>>>>
>>>>>>> Switch to operate and immediately get input power too high alarm @ 91
>>>>>> watts.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Switch to 20 meters (resonant antenna). No issue - 10 watts tune is
>>>>>>> approximately 400 watts out with no error.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Any ideas?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Dave wo2x
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> ______________________________________________________________
>>>>>>> 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]
>>>>>> 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]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>

ANDY DURBIN

KPA-1500 input too high

In reply to this post by Dave wo2x

Was the KPA1500 tested at maximum output power and duty cycle with a loading condition that required drive power to be just below the level that would trip the "input power too high" monitor?

Is it possible that certain loading conditions would require a drive power level high enough to overheat the input resistor?

73,
Andy, k3wyc

______________________________________________________________
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

Dave wo2x

Re: KPA-1500 input too high

Hi Andy

I am thinking the reactance the antenna presents to the tuner may have
something to do with it. Even though SWR shows about 3.7:1 it may well do
with causing the issue.
At 3.636 the capacitance is 719 and inductance is 2100.
The only band I need a tuner is 80 meters. All other bands are resonant (I
do not operate 160)

I've opened a service request on the web site as well as following up with a
detailed email to support along with operating conditions and log file.

The amp will need to visit home to get repaired and updated. Another KPA1500
user with s/n close to mine just got his back from repair and there were a
few updates done to his that are definitely not done to mine.

Dave wo2x

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Andy Durbin
Sent: Monday, April 29, 2019 7:53 AM
To: [hidden email]
Subject: [Elecraft] KPA-1500 input too high

Was the KPA1500 tested at maximum output power and duty cycle with a loading
condition that required drive power to be just below the level that would
trip the "input power too high" monitor?

Is it possible that certain loading conditions would require a drive power
level high enough to overheat the input resistor?

73,
Andy, k3wyc

______________________________________________________________
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]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html