[Elecraft] again: CAL tPa problem

[Marcus Busch [DL1EKC]]

Hi folks,

I'd like to again point Your attention to an old problem with my K2 setup.

My setup includes: K2 s/n 2360 with all official mods and newest firmware, 
KPA100/KAT100 in EC2 enclosure with KPA100 F/W V1.10 and the newest shield 
upgrade.

After making the last F/W updates the problem seemed to have vanished 
away. But I was wrong.

>From time to time KPA100 looses its tPa setting resulting in an odd 
behaviour. Most offen this bug results in a PA HOT display, locking out 
the rig (usually in the middle of a contest). Today tPa jumped to "0 C", 
which was a new version of this bug for me.

I do not have a RF-in-the-shack problem. In fact I have run out of ideas 
how to overcome the issue! Maybe I should go for the dirty way and replace 
the EEPROM with a ROM ?! Is there any way to lock out the WRITE function 
of the EEPROM on hardware level? I have a programming device available.

But there should be a better solution for this. I do not understand 
exactly what is happening in the unit. Maybe high SWR on the feedline is 
causing fluctuations on the AuxBus, which are interpreted as a WRITE 
command?

Did anyone finally overcome this problem? Maybe Wayne could implement a 
new (more complex) communications procedure for writing the tPa value. 
This would make it more unlikely to trigger a WRITE command by random 
AuxBus activity.

Any ideas? Any help?

VY 73 de Marcus, DL1EKC