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

[Dave (NK7Z)]

Have you looked at the calibration setting in it yet?  Not sure if it 
can pull it that far, but that may be what is off.

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 4/7/23 11:12, 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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