[Elecraft] Unusual Behavior K3S / KPA500 Drive Power Greater Than 12 watts

[Tony]

Rick:

I'm glad it's not an issue - can't do without my K3S!

Thanks, Tony


On 3/4/2020 10:42 PM, Rick Bates, NK7I wrote:
> 12 watts is the transition point for the high(er) power amp in the K3 
> to engage, so it's feasible that as that happens, the LPA drops it's 
> output some to make the set power out (to not immediately put out 100 
> watts but what the reading says it should be).
>
> If the K3S has normal output when you're not adjusting the power out, 
> I wouldn't worry about it.
>
> If the K3S in CW is set for the desired power output, phone will be also.
>
> 73,
> Rick NK7I
>
>
> On 3/4/2020 6:20 PM, Tony wrote:
>> Rick Et al:
>>
>> The K3S makes 110 watts measured so the rigs finals appear to be just 
>> fine. Audio is also clean with no distortion. After further testing, 
>> I found that the power drop is only momentary.
>>
>> The RF output on the KPA500 does drop when the drive on the K3S is 
>> increased from 12 to 13 watts, but it quickly rebounds to it's normal 
>> output a few seconds later.
>>
>> This happens on all bands and only takes place during the transition 
>> from 12 to 13 watts. I can hear a relay click during the 12 to 13 
>> watt increase which happens to coincide with the momentary condition 
>> described above.
>>
>> Whatever it is, something changes the way the transmitter behaves 
>> momentarily during that specific power change and my guess is that 
>> it's not unique to my K3S.
>>
>> I spend most of my time on CW and little on SSB so I never noticed 
>> this before. Other than that, the K3S and KPA500 work flawlessly.
>>
>> Tony
>>
>>
>>
>>
>>
>>
>> On 3/4/2020 6:09 AM, Rick Bates, NK7I wrote:
>>> Except that it only happens in SSB, it sounds suspiciously like the 
>>> high power amp (final) has failed in your K3S.  But start with your 
>>> audio.  Are the settings normal (comp, mic gain etc)?
>>>
>>> Can you try another microphone and turn on the monitor function to 
>>> hear what your mic is producing?  Is the two-tone function 
>>> accidentally on?
>>>
>>> What power output can you read when not using the amp and going 
>>> above 12 watts?  If more than 12 watts, a calibrate output would be 
>>> in order for for your confidence.
>>>
>>> Is it confined to one band?
>>>
>>> If you don't get direction of the cause from these tests, a phone 
>>> call to Elecraft service is in order.
>>>
>>> 73,
>>> Rick NK7I
>>>
>>>
>>> On 3/3/2020 10:48 PM, Tony wrote:
>>>> All:
>>>>
>>>> I've noticed an unusual thing happen with my K3S and KPA500 
>>>> amplifier while in SSB mode. When I increase the K3S drive beyond 
>>>> 12 watts, the KPA500 power drops-off dramatically. This only 
>>>> happens in SSB mode.
>>>>
>>>> The KPA500 functions fine with other transceivers as well so the 
>>>> condition appears to be unique to the K3S. Any suggestions?
>>>>
>>>> Tony
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:Elecraft at mailman.qth.net
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to rick.nk7i at gmail.com 
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft at mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to dxdx at optonline.net 
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to rick.nk7i at gmail.com 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to dxdx at optonline.net