It seems that the Holy Grail of many ham HF enthusiasts is a “true balanced ATU.”
The word “true” in there bodes poorly!
It seems that while there are plenty of online experts who have very strong opinions on common mode current, baluns and ATUs, it is very rare that we see quantitative evidence of their assertions, measurements even.
Less commonly does a “true balanced ATU” description include valid measurement of common mode current as evidence of operation.
A “true balanced ATU” project by LY1O in unusual in that it contains a probe purported to measure and display current balance.
Above is a schematic of LY1O’s measurement system, it has a pair of current transformers each with half wave diode detectors in each leg of ATU output. It is important to note that the detectors convert the RF AC wave into a DC value close to the peak value of the AC wave… so they respond to the magnitude only of the current in each leg. Continue reading Balanced ATUs – the Holy Grail?