Once done with the Fundamentals of Electronics, and my leave to visit home, I entered into the 'Systems' part of my training. My training was in the area (as designated at the time) '326X1B'. The 'X' in the code was replaced by a numeral relating to the level of advancement in the area.
The training specifically was titled "Integrated Avionics Component Specialist". The training was on Communication, Navigation and Identification systems on the FB-111 aircraft referred to as the 'Aardvark'. It was a sweep-wing fighter-bomber. There is a Wikipedia entry if you are curious. Even as I was undergoing training, there were those who could cite all the various differences between the many variants of this aircraft. In short, I didn't know and unless it was relevant, I didn't care.
The 'Systems' training used the fundamentals we had learned to build an understanding of the various units on the aircraft we were to maintain. There were voice communications which had various ways of establishing frequencies and operations. There were navigation units, one which sampled various air pressures to result in readouts for true airspeed and other calculations. Another which received transmissions from radio stations to establish the position and speed of the aircraft. Finally identifications units (ominously named 'Identify Friend or Foe') which responded to radar sweeps with information coded in numbers which identified the aircraft.
These were very interesting classes as they ranged from pure analog (the 'air data computer' using chains, gears, and 3D cams to calculate its results) to purely digital (the derivation of the codes sent back by the identification equipment). The digital electronics were of mid-1960's technology (I was receiving this training in 1973). The digital logic was in 'flat packs' incorporating multiple AND and OR gates.
Again I was surprised that the training was so logically built on previous instruction that the concepts came easily. I had no problem with these classes. The best part was the mid instruction break each day. The Airman's Club was right next door and we could get a good cup of coffee and doughnuts to pick up our mornings.
Near the end of instruction a curious request was made of us (in a military service most 'requests' are 'orders' but this wasn't.) As far as I understand there were many Electronics instructors who were rapidly approaching retirement or end of enlistment and insufficient preparation had been made for their replacements. The request was of those who were placed highest in their classes to become 'Instructors'. We were informed by classmates that this could never work because, as opposed to instructors who had come from years of line operations, we would have no 'war stories' to tell to fill odd moments of our instruction. I said 'yes'.