KX1 Cold Weather Operation

[Frederick Dwight]

ED,
   I understand that you have had trouble operating your KX1 in cold temperature. I just wanted to let you know that I have operated my KX1 in much colder temperatures that + 20 degrees F.  Last night I left my KX1 out all night and it was below zero degrees F.  This morning by the time I went outside to see how it would work in the cold it had already warmed up to + 5 degrees F.  I used internal Lithium cells which were partially run down.  Even with these run down and very cold cells my KX1 still seemed to operate normally and put out approximately 1 watt on all 4 bands.  I switched to the menu position which measures the battery voltage.  I read 8 volts key up and approximately 7 volts in the tune position.  I think with fresher cells, or with 6 warm lithium cells in an inside shirt pocket I would l have at least 1.5 watts output on all bands. I have operated the KX1 in the past in cold temperatures, but do not remember exactly how cold it was.  I will do a test when we have some winter weather and see how things work at 30 or 40 degrees below zero F and post the results.  When possible I always try and keep battery packs in an inside shirt pocket for all electronics equipment, especially if it is well below freezing.  Lithium cells hold up better than many other types of cells, but even they lose much of their capacity in cold temperatures.
    One possibility is that when you went to the tune position the voltage sagged below what is required for proper KX1 operation.  In a warmer temperature the same cells may have still worked.  Try new Lithium cells, or a warm external battery pack.  If the problem is not battery related, try operating the KX1 in cold temperatures without the back cover and tap or push on various parts of the board, or parts.  Often problems are thermally related and may only show up in cold or hot conditions.  A solder connection or circuit board trace are real possibilities.  Less likely (at +20 degrees F) would be a component which does not operate in the cold.
Often oscillators will not start and other problems occur in new designs in extreme cold temperatures, however the KX1 is a well proven design in temperatures below where you had difficulty, so this would NOT be my first area of investigation.
    You might be able to find the sensitive area on your board by spraying some of the COLD spray available from Radio Shack and other places on sepecific parts of the board, and or components.  The Cold spray might be especially helpful after you get the problem isolated to a specific area of the board, or a few suspicious components.  Possibly you will need to remove the KX1 completely from its case and carefully distort or bend the board when it is cold to trry and localize the problem.  
      Good luck in finding the problem, and be sure to post your findings on the reflector.
               Rick Dwight   KL7CW   KX1 # 798           Palmer,  Alaska  
   
   
   
   
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