Waiting eagerly for my automatic antenna tuner

You would have noted that during my antenna experiments posted earlier, there were several amateur radio bands on which SWR is a bit above the tunable limit of my FT-710 radio. They are mostly bands on which the antenna resonates for odd harmonics rather than on the fundamental frequency. Sometimes during my loaded coil dipole antenna experiments, the antenna has a similar SWR on an unexpected band. All these will be workable if I have an antenna tuner with a higher range than that in my FT-710 radio which usually tunes up to an SWR of 3:1. That is why I have ordered for an automatic antenna tuner of N7DDC design last week. The website lists it as currently out of stock, but I hope to get it delivered soon. It is quite economical for me with the listed price of ₹8,500 ($97.76) for a 100W auto-tuner. I do not need a higher power rating currently as I do not have a linear amplifier.

As per the design, it is an automatic antenna tuner for HF bands, covering from 1.8 MHz to 55 MHz. That would mean 160m to 6m amateur radio bands, like my FT-710 radio. It has 7 coils and 7 capacitors. As I mentioned in my earlier post on automatic antenna tuner, the microprocessor in the ATU quickly selects a combination of inductors and capacitors and switching between them finds the combination which provides a low SWR. Once a good combination is found, the microprocessor stores the combination in memory for future use.

PIC 16F1938 is the microcontroller used in this antenna tuner. It is an 8 bit microcontroller with clock speed of 32 MHz. A microcontroller is a small, self-contained computer on a single chip that includes a processor, memory, and peripherals. A microprocessor is a general-purpose processor that requires external components for memory and peripherals. PIC 16F1938 is a 28 pin DIP (Dual-In-line-Package) device meant for through the hole mounting on the printed circuit board (PCB).