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K2/KPA100: External Amplifier Keying Test (PA Key) Problem

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JF1KGX

K2/KPA100: External Amplifier Keying Test (PA Key) Problem

Somebody has asked the same before. But nothing has been replied.
Now I have the same problem.

Page 49 of the KPA100 instructions calls for testing the resistance between
ground and the tab of Q9 on the KPA100 board (or center conductor of the PA
KEY
output jack, J7).

According to the instructions, the resistance should drop to less than 3
ohms
when the K2 is put into TUNE mode. Mine only drops to about 270 ohms. The
troubleshooting in the KPA100 manual doesn't even include any information
for
what to do if the resistance doesn't drop to less than 3 ohms.

So far everything else seems to be working correctly with the KPA100.
My serial number is 06617.

Please advise me.

Thanks

Hideki
JF1KGX

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Don Wilhelm-4

Re: K2/KPA100: External Amplifier Keying Test (PA Key) Problem

Hideki,

With power off, check the resistance from the source of Q9 to ground.
If you can check from the lead of Q9 rather than the solder connection.
If it is not zero ohms, you have a soldering problem there.

If the source of Q9 is well grounded, next check the voltage at the Q9
gate during TUNE - it should be in the 3 to 5 volt range. - if lower
than that, check the soldering and value of R1 and the soldering at U1
pin 16 (pin 16 of U1 should be very near 5 volts during TUNE).

If all is good with those checks, Q9 itself is the prime suspect (but I
have never hear of one being a problem).

73,
Don W3FPR

JF1KGX wrote:

> Somebody has asked the same before. But nothing has been replied.
> Now I have the same problem.
>
> Page 49 of the KPA100 instructions calls for testing the resistance between
> ground and the tab of Q9 on the KPA100 board (or center conductor of the PA
> KEY
> output jack, J7).
>
> According to the instructions, the resistance should drop to less than 3
> ohms
> when the K2 is put into TUNE mode. Mine only drops to about 270 ohms. The
> troubleshooting in the KPA100 manual doesn't even include any information
> for
> what to do if the resistance doesn't drop to less than 3 ohms.
>
> So far everything else seems to be working correctly with the KPA100.
> My serial number is 06617.
>
> Please advise me.
>
> Thanks
>
> Hideki
> JF1KGX
>
>
> ______________________________________________________________
> 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
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.392 / Virus Database: 270.13.34/2268 - Release Date: 07/28/09 06:00:00
>
>

______________________________________________________________
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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JF1KGX

Re: K2/KPA100: External Amplifier Keying Test (PA Key) Problem

Don,

I have checked what you advised.
But envrything looks fine.
I don't believe that Q9 itself is something wromg.

Thank you,
Hideki
JF1KGX

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "JF1KGX" <[hidden email]>
Cc: <[hidden email]>
Sent: Wednesday, July 29, 2009 6:47 AM
Subject: Re: [Elecraft] K2/KPA100: External Amplifier Keying Test (PA Key)
Problem

> Hideki,
>
> With power off, check the resistance from the source of Q9 to ground. If
> you can check from the lead of Q9 rather than the solder connection. If
> it is not zero ohms, you have a soldering problem there.
>
> If the source of Q9 is well grounded, next check the voltage at the Q9
> gate during TUNE - it should be in the 3 to 5 volt range. - if lower than
> that, check the soldering and value of R1 and the soldering at U1 pin 16
> (pin 16 of U1 should be very near 5 volts during TUNE).
>
> If all is good with those checks, Q9 itself is the prime suspect (but I
> have never hear of one being a problem).
>
> 73,
> Don W3FPR
>
> JF1KGX wrote:
>> Somebody has asked the same before. But nothing has been replied.
>> Now I have the same problem.
>>
>> Page 49 of the KPA100 instructions calls for testing the resistance
>> between
>> ground and the tab of Q9 on the KPA100 board (or center conductor of the
>> PA KEY
>> output jack, J7).
>>
>> According to the instructions, the resistance should drop to less than 3
>> ohms
>> when the K2 is put into TUNE mode. Mine only drops to about 270 ohms.
>> The
>> troubleshooting in the KPA100 manual doesn't even include any information
>> for
>> what to do if the resistance doesn't drop to less than 3 ohms.
>>
>> So far everything else seems to be working correctly with the KPA100.
>> My serial number is 06617.
>>
>> Please advise me.
>>
>> Thanks
>>
>> Hideki
>> JF1KGX
>>
>>
>> ______________________________________________________________
>> 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
>> ------------------------------------------------------------------------
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database:
>> 270.13.34/2268 - Release Date: 07/28/09 06:00:00
>>
>>
>

Don Wilhelm-4

Re: K2/KPA100: External Amplifier Keying Test (PA Key) Problem

Hideki,

The only other thing that could be wrong is high resistance between the
drain of Q9 and the center of the RCA jack. Check both those places for
good soldering.

Look at the schematic and you will see the circuit is dead simple. Q9
has its source connected to ground, and the gate is connected to U1 pin
16 through R1. The drain of Q9 connects directly to the RCA jack.
There is nothing more to the circuit.
In operation, when U1 pin 16 goes to a high level (5 volts or so), the
voltage at the gate of Q9 is also raised - and will likely be close to 5
volts. In any case, that should allow Q9 to conduct (with very low
resistance) from the drain to the source. With the source connected to
ground, and the drain connected to the center of the RCA jack, if you do
not have a VERY low resistance between the RCA jack and ground, either
there is a bad solder connection or Q9 is faulty.

Check your ohmmeter - if it is reading milliohms instead of ohms, the
350 milliohms would be a normal resistance when TUNE is activated.

73,
Don W3FPR

JF1KGX wrote:

> Don,
>
> I have checked what you advised.
> But envrything looks fine.
> I don't believe that Q9 itself is something wromg.
>
> Thank you,
> Hideki
> JF1KGX
>
> ----- Original Message -----
> From: "Don Wilhelm" <[hidden email]>
> To: "JF1KGX" <[hidden email]>
> Cc: <[hidden email]>
> Sent: Wednesday, July 29, 2009 6:47 AM
> Subject: Re: [Elecraft] K2/KPA100: External Amplifier Keying Test (PA Key)
> Problem
>
>
>
>> Hideki,
>>
>> With power off, check the resistance from the source of Q9 to ground. If
>> you can check from the lead of Q9 rather than the solder connection. If
>> it is not zero ohms, you have a soldering problem there.
>>
>> If the source of Q9 is well grounded, next check the voltage at the Q9
>> gate during TUNE - it should be in the 3 to 5 volt range. - if lower than
>> that, check the soldering and value of R1 and the soldering at U1 pin 16
>> (pin 16 of U1 should be very near 5 volts during TUNE).
>>
>> If all is good with those checks, Q9 itself is the prime suspect (but I
>> have never hear of one being a problem).
>>
>> 73,
>> Don W3FPR
>>
>> JF1KGX wrote:
>>
>>> Somebody has asked the same before. But nothing has been replied.
>>> Now I have the same problem.
>>>
>>> Page 49 of the KPA100 instructions calls for testing the resistance
>>> between
>>> ground and the tab of Q9 on the KPA100 board (or center conductor of the
>>> PA KEY
>>> output jack, J7).
>>>
>>> According to the instructions, the resistance should drop to less than 3
>>> ohms
>>> when the K2 is put into TUNE mode. Mine only drops to about 270 ohms.
>>> The
>>> troubleshooting in the KPA100 manual doesn't even include any information
>>> for
>>> what to do if the resistance doesn't drop to less than 3 ohms.
>>>
>>> So far everything else seems to be working correctly with the KPA100.
>>> My serial number is 06617.
>>>
>>> Please advise me.
>>>
>>> Thanks
>>>
>>> Hideki
>>> JF1KGX
>>>
>>>
>>> ______________________________________________________________
>>> 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
>>> ------------------------------------------------------------------------
>>>
>>>
>>> No virus found in this incoming message.
>>> Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database:
>>> 270.13.34/2268 - Release Date: 07/28/09 06:00:00
>>>
>>>
>>>
>
>
> ______________________________________________________________
> 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
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.392 / Virus Database: 270.13.35/2270 - Release Date: 07/29/09 06:12:00
>
>

JF1KGX

Re: K2/KPA100: External Amplifier Keying Test (PA Key) Problem

Don,

I have checked the below several times. But everything looks fine.
And I also checked my DMM with small value of registers.
It shows correct measurements.
Is it better to RE-solder Q9 for this problem ?

If I have kept this problem on operation, do you think what happen to my K2?
So far have no plan to connect an external amplifier.

Thank you,
Hideki
JF1KGX

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "JF1KGX" <[hidden email]>
Cc: <[hidden email]>; <[hidden email]>
Sent: Thursday, July 30, 2009 4:16 AM
Subject: Re: [Elecraft] K2/KPA100: External Amplifier Keying Test (PA Key)
Problem

> Hideki,
>
> The only other thing that could be wrong is high resistance between the
> drain of Q9 and the center of the RCA jack. Check both those places for
> good soldering.
>
> Look at the schematic and you will see the circuit is dead simple. Q9 has
> its source connected to ground, and the gate is connected to U1 pin 16
> through R1. The drain of Q9 connects directly to the RCA jack.
> There is nothing more to the circuit.
> In operation, when U1 pin 16 goes to a high level (5 volts or so), the
> voltage at the gate of Q9 is also raised - and will likely be close to 5
> volts. In any case, that should allow Q9 to conduct (with very low
> resistance) from the drain to the source. With the source connected to
> ground, and the drain connected to the center of the RCA jack, if you do
> not have a VERY low resistance between the RCA jack and ground, either
> there is a bad solder connection or Q9 is faulty.
>
> Check your ohmmeter - if it is reading milliohms instead of ohms, the 350
> milliohms would be a normal resistance when TUNE is activated.
>
> 73,
> Don W3FPR
>
> JF1KGX wrote:
>> Don,
>>
>> I have checked what you advised.
>> But envrything looks fine.
>> I don't believe that Q9 itself is something wromg.
>>
>> Thank you,
>> Hideki
>> JF1KGX
>>
>> ----- Original Message -----
>> From: "Don Wilhelm" <[hidden email]>
>> To: "JF1KGX" <[hidden email]>
>> Cc: <[hidden email]>
>> Sent: Wednesday, July 29, 2009 6:47 AM
>> Subject: Re: [Elecraft] K2/KPA100: External Amplifier Keying Test (PA
>> Key) Problem
>>
>>
>>
>>> Hideki,
>>>
>>> With power off, check the resistance from the source of Q9 to ground.
>>> If you can check from the lead of Q9 rather than the solder connection.
>>> If it is not zero ohms, you have a soldering problem there.
>>>
>>> If the source of Q9 is well grounded, next check the voltage at the Q9
>>> gate during TUNE - it should be in the 3 to 5 volt range. - if lower
>>> than that, check the soldering and value of R1 and the soldering at U1
>>> pin 16 (pin 16 of U1 should be very near 5 volts during TUNE).
>>>
>>> If all is good with those checks, Q9 itself is the prime suspect (but I
>>> have never hear of one being a problem).
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> JF1KGX wrote:
>>>
>>>> Somebody has asked the same before. But nothing has been replied.
>>>> Now I have the same problem.
>>>>
>>>> Page 49 of the KPA100 instructions calls for testing the resistance
>>>> between
>>>> ground and the tab of Q9 on the KPA100 board (or center conductor of
>>>> the PA KEY
>>>> output jack, J7).
>>>>
>>>> According to the instructions, the resistance should drop to less than
>>>> 3 ohms
>>>> when the K2 is put into TUNE mode. Mine only drops to about 270 ohms.
>>>> The
>>>> troubleshooting in the KPA100 manual doesn't even include any
>>>> information for
>>>> what to do if the resistance doesn't drop to less than 3 ohms.
>>>>
>>>> So far everything else seems to be working correctly with the KPA100.
>>>> My serial number is 06617.
>>>>
>>>> Please advise me.
>>>>
>>>> Thanks
>>>>
>>>> Hideki
>>>> JF1KGX
>>>>
>>>>
>>>> ______________________________________________________________
>>>> 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
>>>> ------------------------------------------------------------------------
>>>>
>>>>
>>>> No virus found in this incoming message.
>>>> Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database:
>>>> 270.13.34/2268 - Release Date: 07/28/09 06:00:00
>>>>
>>>>
>>>>
>>
>>
>> ______________________________________________________________
>> 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
>> ------------------------------------------------------------------------
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database:
>> 270.13.35/2270 - Release Date: 07/29/09 06:12:00
>>
>>
>

Don Wilhelm-4

Re: K2/KPA100: External Amplifier Keying Test (PA Key) Problem

Hideki,

Yes, I would try re-soldering Q9.
No harm will come to the K2 with this problem, but it will not be able
to key an external amplifier.

73,
Don W3FPR

JF1KGX wrote:

> Don,
>
> I have checked the below several times. But everything looks fine.
> And I also checked my DMM with small value of registers.
> It shows correct measurements.
> Is it better to RE-solder Q9 for this problem ?
>
> If I have kept this problem on operation, do you think what happen to my K2?
> So far have no plan to connect an external amplifier.
>
> Thank you,
> Hideki
> JF1KGX
>
>

JF1KGX

Re: K2/KPA100: External Amplifier Keying Test (PA Key) Problem

Don,

I tried re-soldering but nothing has been changed.
Q9 itself might have broken so that I would try to replace new one next.
Let me close this thread once and I will tell you results.

Thank you & 73,
Hideki
JF1KGX

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "JF1KGX" <[hidden email]>
Cc: <[hidden email]>; <[hidden email]>
Sent: Friday, July 31, 2009 7:34 AM
Subject: Re: [Elecraft] K2/KPA100: External Amplifier Keying Test (PA Key)
Problem

> Hideki,
>
> Yes, I would try re-soldering Q9.
> No harm will come to the K2 with this problem, but it will not be able to
> key an external amplifier.
>
> 73,
> Don W3FPR
>
> JF1KGX wrote:
>> Don,
>>
>> I have checked the below several times. But everything looks fine.
>> And I also checked my DMM with small value of registers.
>> It shows correct measurements.
>> Is it better to RE-solder Q9 for this problem ?
>>
>> If I have kept this problem on operation, do you think what happen to my
>> K2?
>> So far have no plan to connect an external amplifier.
>>
>> Thank you,
>> Hideki
>> JF1KGX
>>
>