This post is long. I hope you won't mind. It's good to put all my post-construction observations in one place.
To recap, this project involved building "A Three-Transistor Receiver for the Beginner" from the ARRL book, "How to Become a Radio Amateur." This was the book that inspired me to get into ham radio when my parents gave it to me on my 12th birthday in 1969. Unfortunately, back then, my interest in ham radio only lasted a few years and I never got on the air although I did pass the British amateur radio exam (during this time I was living partly in the U.S. and partly in the U.K.).
Initial report on the performance of this set:
When it was first successfully powered up, there was an extremely loud AC hum in the headphones. Turning off all of the AC appliances in the shack made no difference. However, when I flicked "off" the red power switch on the (passive) APC surge protector through which all the equipment is powered, the hum vanished completely. Interesting.
To maximize sensitivity, I shorted out the "broadcast band filter" at the front end of the set. This raised sensitivity considerably and there was no problem with AM BC breakthrough, except on 160m where a very strong local Spanish station in the Boston area was audible throughout the entire rotation of the bandspread dial. So, I've installed an alligator clip lead back there and plan to short out the filter, except when tuning 160m stations.
I then tested the set for a couple of hours on 80m and 40m in the early daylight hours. For once, I was delighted to hear a group of OMs discussing the medical state of the universe in an SSB net on 75 meters! The audio is excellent and there is plenty of volume. The Jackson ball drive makes it easy to tune in these fellows and null out the "Donald Duck" effect. I would even say that the overall audio quality and ease of tuning is better than my modern Ramsey direct conversion receiver kit with its gazillion IC-mounted transistors, but this could be influenced by pride in my own radio "creation"!
Setting the regeneration is tricky, but I knew that would be the case and having both "Coarse" and "Fine" controls is excellent. You just have to get used to working both the tuning dials and the regen dials simultaneously as you tune through the bands.
On both 80 and 40, I heard plenty of CW, including both fast, experienced operators and much slower people who are sending more in my range (17 to 20wpm). I'm at the 18-character level in the Koch method, so can only partially copy these QSOs because of the gaps in my alphabet. This is providing strong motivation to assimilate the remaining characters!
Perhaps the biggest surprise is that, at least during the daylight hours which is when I did the testing, single-signal reception is entirely possible. I was expecting selectivity to be a major issue with this set but, if I choose the right time of day and the right overall conditions, I think it is capable of being used in serious QSOs. We won't find out for sure until I've built my transmitter and completed the Morse leaning process.
More general observations:
My strongest reaction after going through this intense homebrew experience is that it was an immense amount of work. That's also what made it immense *fun*: this is a hobby you can really sink your teeth into. This was coupled by amazement that, a half century ago, boys, girls, teenagers, adults, actually had the time and the motivation to build this equipment. When you see how over-scheduled many middle-class American kids are, with school and after-school activities, plus the much larger number of (electronic and other) distractions available, it is hard to imagine any but the most obsessive aspiring ham doing something like this nowadays.
Doing this project in the 21st century was a challenge. Finding the parts took nearly a year; the total cost was about $150 perhaps (I did not keep precise track). In real terms, that is actually a lot less than the $50 that the ARRL estimated for this project 45 years ago. Once I had amassed the parts and obtained a whole bunch of tools, the building phase took just over one week which was about 70 hours of my time: apart from my "day job" I did essentially nothing other than eat, build, and sleep. I was being extremely carefuly, because some of the parts in this project are virtually unobtainium nowadays and I didn't want to break them. Also, after about 40 years away from radio, I had to relearn a lot of building skills almost from scratch.
Perhaps the biggest challenge was soldering. In this kind of point-to-point wiring you often have several components leads and wires being soldered to a single terminal lug. It is very hard to get the temperature high enough to make a good joint, without also ruining the components. Also, if I am not mistaken, modern solder doesn't seem to flow as easily or get hot as fast as the old stuff (note: I am *not* using lead-free solder). I'm using a Weller soldering station set to a very hot 850F, with a relatively wide screwdriver tip, but even then it seemed to take a surprising amount of time to get the joint hot enough for the solder to flow in that shiny, bubbly way that indicates a good connection. I did ruin several low-value components (mainly resistors) in the process of building this radio but fortunately I had spares. It did get quite a lot easier as the project progressed so I think I am gaining experience in this essential skill.
As it says in the ARRL book: "The construction details that follow are not the detailed, step-by-step, take-me-by-the-hand instructions you would get if you were building a commercial kit. Kits are fine, but after building one, schematically you might not be able to tell a resistor from a capacitor. But the main reason for building your own is to learn something about radio, and in order to construct this receiver your will need to learn to read circuit diagrams."
I hope this is only the beginning of a homebrew odyssey, taking me through building a simple transmitter and antenna to make my first QSOs and going on to build a more elaborate station and making more of my own design decisions rather than slavishly following the ARRL blueprints. I strongly recommend it to anyone who hasn't tried building their own stuff. It doesn't matter what you build or what technology/era you target, it's the building that counts!
73 de Martin, KB1WSY