[Elecraft] Duty Cycle of FT8 #Elecraft

[Rick NK7I]

Hi Jim,

I've experienced a 10% drop in output as the finals warm up, which 
doesn't ultimately make a large difference, but can be compensated if 
desired (a percentage of 1 dB).

It can run legal limit on all bands; but into a SteppIR, because of the 
transformer/balun in play not being efficient at 6M, limit the output to 
no more than 1 KW (ask me how I know).

I use the default speeds, but I'm also uncomfortable with it going above 
65C, so I step in at that point and boost the fans.

73,
Rick nk7i

On 11/10/2023 11:34 AM, Jim Brown wrote:
>
> I've been told by someone who knows that 1) it is normal for MOSFet 
> devices to lose efficiency as they heat; 2) the KPA1500 can run WSJT 
> modes at rated power except on 6M, where it's best to not run much 
> more than 1 kW for long TX sessions, like meteor scatter. It's an 
> issue un-related to the the MOSFets; and 3) to use default fan 
> settings and let the amp adjust upward as needed.
>
> 73, Jim K9YC
>
>
>
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