Vaccum Tubes (III)

Last thursday we started to work on our radio restoration project. The first step was easy: to identify the tubes.We only had a doubt about the rectifier.  Eddystone 850 had as a full-wave rectifier a 5Z4G vacuum tube; and we got the 5Z4G. We plugged in and there you go! It matched the base perfectly.

We plugged the other ten tubes in but we didn't get anything. And here I started to learn many thing from our technician (I have would liked to learn more). He needed to heard audio sound. That was his method and it marked the way to analyze the whole system. From the last  (the output stage) the whole circuit was analyzed. This procedure took us to identify a damaged capacitor. Later we discover the need to short link an outside jumpers. By the end of that day I was very tired. I went home. But Juan, our technician, decided to stay a little bit more.

Next day, I came early to work in other stuffs. When Juan showed up in my laboratory he came with a big smile. For the first time, in more than forty years it has been with us, it started to work.

Because we have been working in a main hall students have been watching us. We have woken up the curiosity of many people. And this has given me the oportunity to talk to student in a friendly enviroment about how did I happen to be interested in vacuum tubes. It was in 6.002x where I first started to learn about mankind greatest achievement in electronic.