[Elecraft] Upper limits of KPA500?

[Dave Cole]

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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