Re: KX1 lower power only on 40?

Posted by Rick Dwight on Sep 23, 2013; 6:16am
URL: http://elecraft.85.s1.nabble.com/KX1-lower-power-only-on-40-tp7579123p7579125.html

Dan,
  If you tested your KX1 into a good 50 ohm dummy load, the indicated power should have been within 10 or 20% of the correct power either with the KX1 in Cal, or in Tune if you do an ATU tune.
  If you tested it into a resonant 50 ohm antenna, then the reading should also be correct on that band.
  If you test it into a random wire and counterpoise, then the power reading will only be approximately correct if the ATU can tune it to something like < 1.5:1 on bands you measure.  If the ATU can only tune it to say an SWR of 2:1 or 3:1 or higher, then the power reading may be way off....possibly by more than 50 %.  
  The ATU has a very limited tuning range on 80 meters, so a resonant antenna or only very specific lengths of wire and counterpoises can be tuned.  However certain lengths of wires can usually be tuned on 40, 30, and 20 meters.  For example a 26 ft wire antenna with a 17 ft counterpoise laying on the ground will usually tune to well below 2:1 (typically < 1.5:1) on 40, 30, and 20 meters.
   I always try and only use antennas which the ATU can tune to < 2:1 SWR, although at times I have pushed this to 3:1 without problems after about 10 years and thousands of QSO's.  
   My suggestion is to buy or build a 50 ohm dummy load as your first piece of test equipment.
   Good Luck      Rick   KL7CW