[Elecraft] [K2/KX3] Tuning a magloop

[Ron D'Eau Claire]

There are two parts to tuning a small transmitting loop antenna: Resonating the loop at the operating frequency and matching the loop at resonance to the impedance of the feed line.

The Alexloop tuner sounds like a great idea, provided it does both at the same time.  

IMX I tune the loop for maximum noise in the receiver. Properly designed small loops have very high Q, so the peak is very "sharp". 

If I then transmit and find that the SWR is high, I'm sure the coupling between the loop and the feed line is not correct. That is, the loop at resonance is not presenting a 50 ohm impedance to the feed line. 

So the challenge for optimum power transfer is to adjust the coupling and tuning to get both peak noise and low SWR at the same time. 

If you are not worried about feed line losses, I would expect the loop to work just fine using the ATU at the rig to compensate for the odd impedance presented to it by the feed line, but be sure to check the loop tuning after the ATU does its job since it will interact with the loop and shift its resonant frequency somewhat. 

It's like two people standing up in a rowboat. You both work together or you both get wet. 
 

73, Ron AC7AC