RF output Power drop off

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  • Updated 3 years ago
Running 6500 + Expert 1.3k, Windows 10 SSDR and DDutil: I notice that the maximum RF power generated from my 6500 is on 10m at 115w and that it gradually decreases as I go down the bands to around 95w on 80m. All measurements/observations taken in CW mode. I also notice that after initially showing such power levels after only less than a minute the power gradually drops back by as much as 5 or 6 watts and will then stabilize a bit. This also seems to happen at low power levels which can be a nuisance when driving the amp as its power then starts to drop back substantially.  Does anyone else see similar or can offer any thoughts?  I have set the DC PSU voltage to 14v as read on DDutil.  PSU is GSV3000.
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Posted 3 years ago

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Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

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Official Response
PA efficiency is temperature dependent so there will be some drop in power as the transistors get warmer.  Since you lowest wattage is 95W, which is within the nominal specifications, that is not something to be too concerned about

What is a more concerning is the 115W when initially transmitting.  This sounds like the PA may need to be recalibrated by an authorized service center, but to know for certain, I am converting this topic to a HelpDesk support ticket so we can get a set of complete power curve data points in the initial and warmed up state.