Teardowns of vintage gear in which you carefully note component values, construction techniques, and create a schematic from scratch are a great introduction to vacuum tubes. The next level (and the focus of this article) is to restore tube-type devices, starting with a tabletop radio. Not only will you learn to work with the technology, but you’ll have something of value when you’re done.
Magnetic loop antennas are becoming popular today because they can be very efficient for their size, do not need radials (even though most designs are vertically polarized), have useful takeoff angles, and can be easily rotated to peak or null a signal. Here’s how I designed a convenient setup for myself.
In mid 2012, I noticed an amplifier on eBay that was out of a 1952 Rock-ola 1436 jukebox, and just had to have it. It was essentially a dead carcass, so I decided to restore the amplifier and make it able to stand alone. I wanted to make the restored amplifier as authentic as possible to the 1952 version.
For audiophiles, musicians, and ham radio operators, the soft glow of the vacuum tube filament is not only an indication of function, but a nostalgic trigger for memories of simpler times. Though they may have been outpaced by tiny transistors and integrated circuits, these workhorses still may have something to offer in many modern devices.
This six-digit, beautifully designed timepiece showcases cold war era components — Numitrons instead of Nixie tubes — along with modern LEDs and a Microchip PIC to create not only a useful clock but a great conversation piece as well.
Even though they're ancient by today's standards, old tube radios can almost always be brought back to life, and there's still plenty of broadcasts out there for them to receive! Not to mention, they just look so classy and have a presence few modern electronics can match.
In the fast moving world of digital electronics, I find it incredible that the vacuum tube — a piece of early 20th century analog technology — has managed to survive. It should have bitten the dust long ago but that just did not happen. This back-to-the-future one-tube radio is made with readily available parts, operates on 12 volts, and offers amazing performance.