[Elecraft] "Not Inst" message for KAT100 ..Possible solution?

[Tony Breathnach]

I recently had an intermittent problem on my K2 when switching and tuning antennas.Suppose I selected Ant 2 and pressed Tune, the atu would do the business and match the antenna. If I then changed to Ant 1 I could get the "Not Inst" message from time to time. If I powered off and on again the fault cleared but could repeat itself. 
I carried out many checks on soldering, components, replaced the two 2N7000 transistors and even upgraded the KAT100 firmware to no avail. I must have had Gary demented at Elecraft.

Then by a pure fluke I discovered that if I took my time and switched antennas and tuned each in turn leaving a second or two between each step, then there was no problem. By this I mean select Ant 2, wait about two seconds, press Tune and allow the tuner to match the antenna. When Antenna 2 was tuned I waited another second or two before selecting Ant 1 and a further second or so before pressing Tune for Ant 1. Being a little more patient like this never causes the "Not Inst" message to appear. However, if I rush the procedure the message will invariably appear.Timing is the important ingredient.

I am not sure if this is just an oddity with my particular K2. I pass it on for what it is worth and it might prevent others tearing their hair out as I almost did.

de Tony EI5EM