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KPA100 Initial Test Problem

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Eugene Worth

KPA100 Initial Test Problem

Hello all:

I am building a remote KPA100 in an EC-2 enclosure. The KAT100-2 has already been built and tested correctly.

My K2 is S/N 5717 with firmware 2.04P.

Problem: All the test point voltages are nominal (+/-10%) except U1 pin 27. The voltage listed is 5.8 … I got 3.99 volts. Everything else in the section of initial tests is flawless.
U1 pin 20 = 5.04
U1 pin 28 = 5.56
U2 pin 10 = 13.65
U4 pin 1 = 13.65
U4 pin 11 = 5.04
All of the other values are 0 as noted in the checklist.
On initial power up, the K2 power supply voltage was 13.8 and current 0.36.

Any hints on where to look for the problem?

Thanks.

gene
WG7GW

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Don Wilhelm-4

Re: KPA100 Initial Test Problem

Gene,

Check RP1 pin 7. If you do not find close to 8 volts there, you will
need to track down the source of the problem in the 8R input to the KPA100.

If you find the voltage at RP1 pin 7 is not anywhere near 8 volts, check
the source - what is the voltage on the K2 Control Board Q2 collector -
that is the source for 8R. If the two points have significantly
different voltages, you will have to find the discontinuity in the
wires, connectors and PC traces between those two points.

If RP1 pin 7 is OK, but U1 pin 27 is lower than normal, that may be OK -
pin 27 of U1 is simply drawing a bit more power than usual - as long as
the 5R and 5T outputs from U1 at pins 13 and 14 work OK, you will not
have a problem.

73,
Don W3FPR

On 10/25/2011 11:26 AM, Eugene Worth wrote:

> Hello all:
>
> I am building a remote KPA100 in an EC-2 enclosure. The KAT100-2 has already been built and tested correctly.
>
> My K2 is S/N 5717 with firmware 2.04P.
>
> Problem: All the test point voltages are nominal (+/-10%) except U1 pin 27. The voltage listed is 5.8 … I got 3.99 volts. Everything else in the section of initial tests is flawless.
> U1 pin 20 = 5.04
> U1 pin 28 = 5.56
> U2 pin 10 = 13.65
> U4 pin 1 = 13.65
> U4 pin 11 = 5.04
> All of the other values are 0 as noted in the checklist.
> On initial power up, the K2 power supply voltage was 13.8 and current 0.36.
>
> Any hints on where to look for the problem?
>
> Thanks.
>
> gene
> WG7GW
>
> ______________________________________________________________
> 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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Help: http://mailman.qth.net/mmfaq.htm
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Please help support this email list: http://www.qsl.net/donate.html

Eugene Worth

Re: KPA100 Initial Test Problem

In reply to this post by Eugene Worth

Resolved after much hair pulling.

Thanks to Don and Gary Surrency for all of the suggestions and most of their day answering emails as to troubleshooting! Here is the setup: K2 with KIO2. I have built the KAT100 in the EC-2 and am building the KPA100 as an outboard amplifier in the EC-2 enclosure. This is so I can still use the K2 as a QRP/Portable rig whenever wanted but have 100 watts at home location.

There is a website describing "splitting" the K2100 into the configuration above, but it doesn't cover what we found to be a "problem." (You can Google KK7P) The 8R line from the K2 through the KIO2 has a 3.9 kOhm resistor in line. It turns out that the KAT100 has the same value resistor in line as well. When you take the cable from the KIO2 then pass the signal through the KAT100, the 8R line is no longer 8 volts, but 4 volts.

So, if you are building the configuration above, be aware that (Rev H KPA100) page 26 initial checks, you will find the U1 (KPA100 MCU) pin 27 value to be 3.99 volts. This is the nominal value and not an error in building.

Thanks again!

gene
WG7GW

> Gene,
>
> Check RP1 pin 7. If you do not find close to 8 volts there, you will
> need to track down the source of the problem in the 8R input to the KPA100.
>
> If you find the voltage at RP1 pin 7 is not anywhere near 8 volts, check
> the source - what is the voltage on the K2 Control Board Q2 collector -
> that is the source for 8R. If the two points have significantly
> different voltages, you will have to find the discontinuity in the
> wires, connectors and PC traces between those two points.
>
> If RP1 pin 7 is OK, but U1 pin 27 is lower than normal, that may be OK -
> pin 27 of U1 is simply drawing a bit more power than usual - as long as
> the 5R and 5T outputs from U1 at pins 13 and 14 work OK, you will not
> have a problem.
>
> 73,
> Don W3FPR
>
> On 10/25/2011 11:26 AM, Eugene Worth wrote:
>> Hello all:
>>
>> I am building a remote KPA100 in an EC-2 enclosure. The KAT100-2 has already been built and tested correctly.
>>
>> My K2 is S/N 5717 with firmware 2.04P.
>>
>> Problem: All the test point voltages are nominal (+/-10%) except U1 pin 27. The voltage listed is 5.8 ? I got 3.99 volts. Everything else in the section of initial tests is flawless.
>> U1 pin 20 = 5.04
>> U1 pin 28 = 5.56
>> U2 pin 10 = 13.65
>> U4 pin 1 = 13.65
>> U4 pin 11 = 5.04
>> All of the other values are 0 as noted in the checklist.
>> On initial power up, the K2 power supply voltage was 13.8 and current 0.36.
>>
>> Any hints on where to look for the problem?
>>
>> Thanks.
>>
>> gene
>> WG7GW
>>