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K2 problems

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W1SBY

K2 problems

Hi all,

I am having problems with my K2 after moving it from one room to another.
K2/100 into a dummy load
On all bands I get a HiCur notice when I try to tune, when the PA is
disabled (10 watts or less) the SWR shows 1:1 OK
On all bands with the PA enabled (over 10 watts) I get the HiCur notice
and the SWR indicates a fluctuating range from 3:1 to 9.9 to one
depending on band and power setting.
In all instances the power out indication is markedly lower than the
setting. At 10 watts set, I show 4 watts, at 90 watts set I show 7 watts.
I have misplaced my analog wattmeter during the moving process but my
LDG autotuner shows that output is actually near or above my settings.
Not a good diagnostic tool I know.
I think something has definitely gone awry, any ideas on where to start?

Thanks,
Allen, W1SBY
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73 de Allen, W1SBY

Don Wilhelm-4

Re: K2 problems

James,

Can you use an external wattmeter between the K2 and the dummy load?
With the power control set at greater than 20 watts and less than 50
watts, what is the power read on the external wattmeter when you do a TUNE?
If it is 100 watts or greater, then you need to replace D16 and D17 in
the KPA100.

If the actual power indicated above is in the range of 20 watts, and you
still get the HiCur messages, you will have to do a bit more
troubleshooting - remove the KPA100 (physically) and power the base K2
through the coaxial power connector and take the ouput to the dummy load
from the BNC antenna jack. Set the power at 5 watts and do a TUNE. Do
you see a HI CUR warning? If so, what is the actual power output?
Next set the power knob to 12 watts and do a TUNE again - if you see
HiCur and the output is less than 12 watts, you have a problem with the
Low pass filter in the base K3 - but if it occurs on all bands, look for
the problem at T4 rather than the low pass filter.

73,
Don W3FPR

On 12/3/2010 11:06 PM, Allen Wisbey, W1SBY wrote:

> Hi all,
>
> I am having problems with my K2 after moving it from one room to another.
> K2/100 into a dummy load
> On all bands I get a HiCur notice when I try to tune, when the PA is
> disabled (10 watts or less) the SWR shows 1:1 OK
> On all bands with the PA enabled (over 10 watts) I get the HiCur notice
> and the SWR indicates a fluctuating range from 3:1 to 9.9 to one
> depending on band and power setting.
> In all instances the power out indication is markedly lower than the
> setting. At 10 watts set, I show 4 watts, at 90 watts set I show 7 watts.
> I have misplaced my analog wattmeter during the moving process but my
> LDG autotuner shows that output is actually near or above my settings.
> Not a good diagnostic tool I know.
> I think something has definitely gone awry, any ideas on where to start?
>
> Thanks,
> Allen, W1SBY
>

Don Wilhelm-4

Re: K2 problems

In reply to this post by W1SBY

Sorry Alan,
That was to be directed to you, and not to James.

73,
Don W3FPR

---------------------------------------------------------------

James,

Can you use an external wattmeter between the K2 and the dummy load?
With the power control set at greater than 20 watts and less than 50
watts, what is the power read on the external wattmeter when you do a TUNE?
If it is 100 watts or greater, then you need to replace D16 and D17 in
the KPA100.

If the actual power indicated above is in the range of 20 watts, and you
still get the HiCur messages, you will have to do a bit more
troubleshooting - remove the KPA100 (physically) and power the base K2
through the coaxial power connector and take the ouput to the dummy load
from the BNC antenna jack. Set the power at 5 watts and do a TUNE. Do
you see a HI CUR warning? If so, what is the actual power output?
Next set the power knob to 12 watts and do a TUNE again - if you see
HiCur and the output is less than 12 watts, you have a problem with the
Low pass filter in the base K3 - but if it occurs on all bands, look for
the problem at T4 rather than the low pass filter.

73,
Don W3FPR

On 12/3/2010 11:06 PM, Allen Wisbey, W1SBY wrote:

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W1SBY

Re: K2 problems

Don,

I finally got enough time to do some more tests. The KPA100 is putting
out in excess of 100 watts on all bands when set for 30 watts. An
interesting thing though... the radio acted fine when I first started
testing, then suddenly went to bad behavior.

So, my next question just to clarify; Replacing D16 & D17 should fix it?
Also what may have happened to cause this?
You repaired and aligned this radio a couple months ago, (SSB chip was
mounted backwards). All was well until I moved my shack to a different
room.
The ONLY difference in setup was I actually grounded the radio to a
ground rod outside the new location.

73 de Allen, W1SBY

On 12/4/2010 12:00 AM, Don Wilhelm wrote:

> Sorry Alan,
> That was to be directed to you, and not to James.
>
> 73,
> Don W3FPR
>
> ---------------------------------------------------------------
>
> James,
>
> Can you use an external wattmeter between the K2 and the dummy load?
> With the power control set at greater than 20 watts and less than 50
> watts, what is the power read on the external wattmeter when you do a
> TUNE?
> If it is 100 watts or greater, then you need to replace D16 and D17 in
> the KPA100.
>
> If the actual power indicated above is in the range of 20 watts, and
> you still get the HiCur messages, you will have to do a bit more
> troubleshooting - remove the KPA100 (physically) and power the base K2
> through the coaxial power connector and take the ouput to the dummy
> load from the BNC antenna jack. Set the power at 5 watts and do a
> TUNE. Do you see a HI CUR warning? If so, what is the actual power
> output?
> Next set the power knob to 12 watts and do a TUNE again - if you see
> HiCur and the output is less than 12 watts, you have a problem with
> the Low pass filter in the base K3 - but if it occurs on all bands,
> look for the problem at T4 rather than the low pass filter.
>
> 73,
> Don W3FPR
>
> On 12/3/2010 11:06 PM, Allen Wisbey, W1SBY wrote:
>> Hi all,
>>
>> I am having problems with my K2 after moving it from one room to
>> another.
>> K2/100 into a dummy load
>> On all bands I get a HiCur notice when I try to tune, when the PA is
>> disabled (10 watts or less) the SWR shows 1:1 OK
>> On all bands with the PA enabled (over 10 watts) I get the HiCur notice
>> and the SWR indicates a fluctuating range from 3:1 to 9.9 to one
>> depending on band and power setting.
>> In all instances the power out indication is markedly lower than the
>> setting. At 10 watts set, I show 4 watts, at 90 watts set I show 7
>> watts.
>> I have misplaced my analog wattmeter during the moving process but my
>> LDG autotuner shows that output is actually near or above my settings.
>> Not a good diagnostic tool I know.
>> I think something has definitely gone awry, any ideas on where to start?
>>
>> Thanks,
>> Allen, W1SBY
>>
> ______________________________________________________________
> 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
>
>

73 de Allen, W1SBY

Don Wilhelm-4

Re: K2 problems

Alan,

Remove the KPA100 shield and check the diodes with your ohmmeter. There
are other possible faults that could have crept into your KPA100
wattmeter circuits, but the diodes are the first suspects since that is
most common. If the diodes check good, then I can help you with the
additional troubleshooting.

The normal cause for the failure of D16 and D17 is a static discharge
coming in on the antenna.
If your antenna does not have a DC path across the feedline, that can
happen when you connect the antenna if the antenna has developed a
static charge from wind, rain, snow, and yes lightning.

With a PL-259 UHF connector, the center conductor is normally mated in
the jack before the shell, so if you had a good ground on the K2 and a
static charge on the feedline, that could zap the diodes.

I am not certain that is how it happened, but it is a definite possibility.
Is there any way you can put an RF Choke or high value resistor (above
5000 ohms) across your antenna feedlines - if you have an RF switch in
the shack, that is a good place for it. Another way is to mount the
choke or resistor in a PL-259 shell and add a TEE adapter at the back of
the K2 - one of the female ends of the TEE connects to the PL-259 with
the resistor and the antenna connects to the other female end.

73,
Don W3FPR

On 12/7/2010 9:27 PM, Allen Wisbey, W1SBY wrote:

> Don,
>
> I finally got enough time to do some more tests. The KPA100 is putting
> out in excess of 100 watts on all bands when set for 30 watts. An
> interesting thing though... the radio acted fine when I first started
> testing, then suddenly went to bad behavior.
>
> So, my next question just to clarify; Replacing D16& D17 should fix it?
> Also what may have happened to cause this?
> You repaired and aligned this radio a couple months ago, (SSB chip was
> mounted backwards). All was well until I moved my shack to a different
> room.
> The ONLY difference in setup was I actually grounded the radio to a
> ground rod outside the new location.
>
> 73 de Allen, W1SBY
>
> On 12/4/2010 12:00 AM, Don Wilhelm wrote:
>> Sorry Alan,
>> That was to be directed to you, and not to James.
>>
>> 73,
>> Don W3FPR
>>
>> ---------------------------------------------------------------
>>
>> James,
>>
>> Can you use an external wattmeter between the K2 and the dummy load?
>> With the power control set at greater than 20 watts and less than 50
>> watts, what is the power read on the external wattmeter when you do a
>> TUNE?
>> If it is 100 watts or greater, then you need to replace D16 and D17 in
>> the KPA100.
>>
>> If the actual power indicated above is in the range of 20 watts, and
>> you still get the HiCur messages, you will have to do a bit more
>> troubleshooting - remove the KPA100 (physically) and power the base K2
>> through the coaxial power connector and take the ouput to the dummy
>> load from the BNC antenna jack. Set the power at 5 watts and do a
>> TUNE. Do you see a HI CUR warning? If so, what is the actual power
>> output?
>> Next set the power knob to 12 watts and do a TUNE again - if you see
>> HiCur and the output is less than 12 watts, you have a problem with
>> the Low pass filter in the base K3 - but if it occurs on all bands,
>> look for the problem at T4 rather than the low pass filter.
>>
>> 73,
>> Don W3FPR
>>
>> On 12/3/2010 11:06 PM, Allen Wisbey, W1SBY wrote:
>>> Hi all,
>>>
>>> I am having problems with my K2 after moving it from one room to
>>> another.
>>> K2/100 into a dummy load
>>> On all bands I get a HiCur notice when I try to tune, when the PA is
>>> disabled (10 watts or less) the SWR shows 1:1 OK
>>> On all bands with the PA enabled (over 10 watts) I get the HiCur notice
>>> and the SWR indicates a fluctuating range from 3:1 to 9.9 to one
>>> depending on band and power setting.
>>> In all instances the power out indication is markedly lower than the
>>> setting. At 10 watts set, I show 4 watts, at 90 watts set I show 7
>>> watts.
>>> I have misplaced my analog wattmeter during the moving process but my
>>> LDG autotuner shows that output is actually near or above my settings.
>>> Not a good diagnostic tool I know.
>>> I think something has definitely gone awry, any ideas on where to start?
>>>
>>> Thanks,
>>> Allen, W1SBY
>>>
>> ______________________________________________________________
>> 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
>

W1SBY

Re: K2 problems

Don and the group,

I finally got around to replacing D16 and D17, as usual your diagnosis
was spot on. I now have a happy K2 again!

Thanks so much for your help.

73 de Allen, W1SBY

On 12/7/2010 8:53 PM, Don Wilhelm wrote:
> Alan,
>
> Remove the KPA100 shield and check the diodes with your ohmmeter. There
> are other possible faults that could have crept into your KPA100
> wattmeter circuits, but the diodes are the first suspects since that is
> most common. If the diodes check good, then I can help you with the
> additional troubleshooting
<balance deleted for brevity>
______________________________________________________________
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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73 de Allen, W1SBY