[Elecraft] [K3] Betaware 3.06 Problem

[North Pole]

Recently put K3 #2773 on the air with firmware revision earlier than the current 2.78 official release.  Though I have a lot to learn yet,  I am quite pleased with the many unique performance features of the K3.  Thanks to reading many posts on agc settings used by other folks I was happily finding the settings that work for me.

Last night I decided to try my first firmware upgrade and load the newest betaware revision 3.06.  Having a little trouble finding the 3.06 I first downloaded, successfully, firmware 2.78.  I listened to the receiver briefly and all was fine.  However, I wanted to try the soft decay and longer hold, slower agc settings featured in the 3.03 release.

I figured 3.06 was the latest and successfully loaded it to my K3.  Unfortunately, when the transceiver returned to normal operation it produced the most god awful piercing, deafening, howl in my sounds sweet spkr  it scared me. hi!  The K3 display locked up with s meter lcd bars fully lighted to 60 over 9 and no way to turn rig off, change bands or modes.  Removing the 14 volt power supply was the only remedy but then the rig came on the same as it went off but waiting 3 to 4 minutes or more would gradually return to normal ssb receive. 

When I tried to change modes or filters it would do the same screeching howl and lock up.   I don't have any hearing capacity to spare but that howl was excruciating even when I knew it was coming!!

Thankfully,  I was able (though not easily)  to reload firmware rev 2.78 and my K3 is operating like it should with no apparent damage other than my eardrums. 

I am really gun shy now about trying 3.06 again and may not do any updating until a revision is officially released.  My nature is that of a tinkerer and experimenter so I hate to give up that option.

Can anyone shed any light on what might have happened?  Or has this happened to anyone else?  I am anxious to hear from the reflector members that might have a clue.  Thanks for reading. Larry - W8CCY