[Elecraft] K3: Using 40m Loop for 10m

[David Cutter]

Hi Phil

I think the first thing that occurs to me is: are you feeding this loop with one coax and just switching between bands?  

David
G3UNA



  I use my K3 to participate in a daily 10m CW net (28.130, 7pm PST).  

  I've been experimenting with two antennas for the net:  40m full wave, vertically-oriented loop, relying on my KAT3 for a match, and a home-brew 10m rotatable dipole cut pretty close to resonate at 28.130.

  When using the loop for operating on 40m, of course I get great matching without the KAT3.  When using the loop for the 10m net, the KAT3 works hard, but it does provide close to a 1:1 indicated match.

  When using the loop on 40m, I can vary the output from minimum to full (approx 120w).  But when I use the 40m loop on 10m, the power out shows 50w max.  If I maintain the power output control to indicate 100w, I get "Hi Cur" indications during a transmission that exceeds a minute or so.  (These Hi Cur indications are never instantaneous in these situations, nor are they consistent.)

  I'm sure there is some form of safety protection for the K3 transmitter, but I could not find documentation on how the transmitter might behave when it's connected to such a mismatched antenna, even with the presumed match using the KAT3.

  Can someone educate me on this?  I know my 40m loop is not supposed to do well on 10m.  I was frankly surprised that the KAT3 matched it as good as it did!

  Believe it or not, my ground wave signal for our local 10m CW net has been reported by the net control station as much better with the loop than it is with the 10m rotatable dipole.  (Using the 10m dipole, I can see power out of 100+ watts, and don't get the Hi Cur warnings -- the signal just 
  isn't reported by most as being strong like the loop.)

  Any insight on this would be greatly appreciated.

  73, Phil, WA7URV K3 #1206



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