[Elecraft] [K3] Workaround for FPF Firmware Load Failure: Cool it down in the fridge first

[Andrew Siegel]

My K3 (s/n 6000+) has developed the FPF Load failure problem: the K3 
Utility times out after a few minutes when trying to update the FPF 
firmware, leaving "FPF Load" showing on the K3 display, and leaving the 
K3 unusable.

This happens on Windows, Mac, and Linux, using three different 
high-quality USB-to-serial adapters: Keyspan USA-19HS, Tripp Lite 
U209-000-R, and Plugable PL2303-DB9. I can upgrade the MCU and DSP 
firmware without a problem. The FPF load fails regardless of the version 
of the K3 utility I use, the version of MCU or DSP firmware already 
installed on the K3, or the version of FPF firmware that I am attempting 
to install.

In a panic after seeing the FPF load failure just before this past Field 
Day, I came up with a workaround that has worked twice now:

==> Put the K3 in the fridge for an hour or two before doing the FPF 
firmware upgrade.

On my K3, the FPF load fails when the front panel temperature is even at 
my relatively low house temperature of 19C (as displayed on the front 
panel). The longer the K3 has been powered up, the warmer the FP gets, 
and the less time it takes for an FPF firmware load to fail. When I 
activate View->Trace in the K3 Utility and watch the serial interaction 
under these conditions, I observe that the rig starts taking longer and 
longer to acknowledge packets sent, until finally it stops ACKing 
completely, at which point the utility gives up.

When I refrigerate the K3, the reported FP temperature drops to 9C, and 
the FPF firmware load works reliably. There are no dropped ACKs.

Your mileage may vary; refrigerate your K3 at your own risk, and 
definitely do not freeze it.

73,
Andy, N2CN