MagLoop tuning introduction
You should never use an antenna tuner with a Magnetic Loop antenna, because doing so can destroy the MagLoop’s tuning box.
Please, do not ever transmit with more than 5 watts until after the loop has been properly tuned. Only after your Alpha Antenna MagLoop has been tuned to an SWR of less than 2.1:1 should you use more than 5 watts.
MagLoop Tuning Basics
To tune a MagLoop, turn your internal or external antenna tuner off by switching it into by-pass. You will then tune the loop using the manual tuning knob on the MagLoop or the remote control. You also need to retune the loop if you change your frequency enough that the SWR exceeds 2.5:1. Basically, whenever the SWR exceeds 2.5:1, then you should retune the Alpha magnetic loop antenna.
Tuning Technique
Use this 2-step process to tune your Alpha MagLoop antenna:
Step 1. Tune the antenna to provide the loudest noise floor from your radio while it is in SSB mode.
Step 2. Use an external SWR meter, your radio’s SWR meter, or an Antenna Analyzer to tune for the lowest SWR.
NOTE – Loops are high Q, which means you may affect SWR when standing close to the antenna. This can also occur with many other antennas that are highly efficient. However, you may not notice this with other options that are less efficient. So, you may want to use a technique called ‘reverse tuning’ when using the highly efficient Alpha Loop antenna.
REVERSE TUNING (Offset frequency while tuning for hand capacitance) While tuning with the analyzer and to off-set the effect of hand capacitance, a technique called reverse tuning can be used. To reverse-tune a magnetic loop, tune for minimum SWR while touching the Black Knob on the Alpha Loop’s tuning box, say 1.9:1; and then when you remove your hand you might see 4.3:1 for example; then all you have to do is tune for 4.3:1 while your hand is onthe knob to achieve an SWR of 1.9:1 when you remove your hand.
For more information about antennas see Antennas (arrl.org)
