[Elecraft] [P3] P3 woes - repaired but now claims my K3s puts out 873W!

[Dave New, N8SBE]

Don,

The KPA500 (and K3s) both show the correct wattage - 100W barefoot and 
about 26W out of the K3s when the KPA500 is inline, and about 500W out 
of the KPA500.

I tried changing the P3 SensorCal value from 500 (default) to 350 (min) 
but that only dropped the wattage shown by a little less than half.

73,
-- Dave, N8SBE

On 2023-04-07 16:48, W3FPR wrote:
> Dave,
> 
> What power is displayed on the KPA500?  The KPA500 would fault if
> indeed the K3s is putting out that much power.  The KPA500 power bar
> is pretty accurate, just a bit coarse in its increments.
> 
> I think a power calibration is in order for the P3 power indicator.
> 
> 73,
> Don W3FPR
> 
> On 4/7/2023 2:12 PM, Dave New, N8SBE wrote:
>> So, I was the guy that had a P3 display/boot problem recently.
>> 
>> I sent it to the mother ship for repair, and they found that (get 
>> this) the 12V supply was shorted to the 3.3V supply (eep!).
>> So, a new(er) I/O board (which contains the supplies) and a 
>> replacement blown 3.3V LCD controller later, I have an (almost) fully 
>> functional P3 again.
>> 
>> EXCEPT, the TX Monitor function is now funky.  It claims that my K3s 
>> is putting out 873 (or so) watts!  I've tried both sensors (I had a 
>> 200W HF sensor on the shelf since I added a KPA500 and changed to a 
>> 2KW HF sensor), and although the scale max changes on the P3 display 
>> when I change sensors, it still way overstates my output power.  The 
>> KPA500 is showing 1360 watts on the P3!
>> 
>> I unplugged/re-plugged everything, did a visual inspection of the TX 
>> Monitor adapter board under a lighted magnifying glass, looking for 
>> missing/broken SMD resistors or caps, but so far no soap.
>> 
>> I'm wondering if the new revision I/O board is somehow incompatible 
>> with the older TX Monitor board, or maybe there is a missing 1M-ohm 
>> resistor to ground on the I/O board at the sensor connector, or an 
>> incorrect series resistor value there.
>> 
>> And yes, I sent a note to support, but I haven't heard back, yet. 
>> Wondering if anyone (Alan?) has any ideas where this behavior is 
>> coming from.  The wattmeter in both my K3s and KPA500 are working 
>> normally.  It's just the P3 wattmeter that's gone off the deep end, 
>> now.
>> 
>> Thanks, and 73,
>> -- Dave, N8SBE
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