[Elecraft] Upper limits of KPA500?

[Rick Bates, NK7I]

I didn't add the obvious, FT8 in that manner is a 50% duty cycle but 
with enough time to 'catch the breath'.

I remember back when it first came out, Wayne suggested to 'run it with 
all the LEDs lit' or something along that line but... it's capable of 
MUCH more than 500 watts and wisely better limited by firmware upgrades 
(in the early days I watched it put out almost 700, at which point I was 
far more cautious).  It's nice to know there is a certain amount of 
'overhead'.

Rick NK7I


On 5/3/2020 8:23 PM, Dave Cole wrote:
> Hi Rick,
> That is how mine behaves as well, almost exactly like that... However, 
> I will be running SSTV, and that is hard on the amp...  I need to do a 
> bit more testing prior to that.
>
> As someone else said upthread, half power is really tough on the amp...
>
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> ARRL Volunteer Examiner
> ARRL Technical Specialist
> ARRL Asst. Director, NW Division, Technical Resources
>
> On 5/3/20 7:52 PM, Rick Bates, NK7I wrote:
>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>>
>> At 530 watts output (on the display and utility) into a 1.13:1 
>> antenna load (SteppIR) for a ten minute calling period (Mongolia then 
>> Oman), the temp rose to 66C; a few moments of elevated fan quickly 
>> brought that down to the low 60's between transmissions.
>>
>> Ambient room temp 77F.  (Both calls succeeded.)
>>
>> Rick NK7I
>> North Idaho
>>
>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>>> "It is interesting to hear how others experience their KPA500s over 
>>> various conditions."
>>>
>>> I have over a years's worth of KPA500 data recorded but it takes 
>>> some effort to run it through the Excel templates to make pretty plots.
>>>
>>> My KPA500 temperatures are strongly influenced by ambient 
>>> temperature.  Shack temperature is often over 30 deg C in the summer 
>>> months and it's not at all unusual for my fan to run at level 3 in 
>>> FT8 QSO.  I think I have only reached fan speed 5 twice and that was 
>>> while running temperature tests not while operating.   I terminated 
>>> those tests at fan speed 5 and didn't wish to push it any higher.
>>>
>>> So many people seem to think reducing the output power will keep the 
>>> temperature down.  It does not.   Half power is about the worst heat 
>>> dissipation condition for the KPA500.
>>>
>>> 73,
>>> Andy, k3wyc
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