If you want to restore old radios you need the following.
A Tube Tester helps a lot but is not absolutely necessary.
- A soldering iron.
- A Capacitor Tester.
- A VTVM (Vacuum Tube Voltmeter).
- A Tube Manual.
A soldering iron.You can't work on any electronics without one. The 20 and 25 watt kind for PC boards are a little light for working on old radios and amplifiers. You don't want one of those 400 watt monsters designed for soldering a fender on a car, either. 150 is still a little large. What I recommend is something in the range of 50 to 100 watts. If you decide to buy a soldering gun on eBay be sure you can get or make tips for it. It will be a useless museum piece with out them.
A Capacitor Tester.There are capacitor testers and there are capacitor testers. You need one that can apply the actual operating voltage to the capacitor under test. You can't test a 150 volt capacitor by applying 3 volts to it as many modern testers do. If you do, many times it will test perfectly good but in the tube circuit will blow other components.
What I recommend is a Heathkit model IT-11 or IT-28. These two models are essentially the same. The IT-11 is from Heath's gray period and the IT-28 is from their tan period. They had discontinued this model before their blue period began. Here is what they look like.
The place to look for them is eBay. At any given moment there is at least one and usually two or three. Go to the eBay search and type in "Heathkit capacitor" without the quotes. Some sellers list them as capacitor testers and others as capacitor checkers and a few as capacitor bridges. You may get a few extra hits on capacitor substitution boxes but that won't kill you. Don't bid anymore than you can afford to pay.
You can use a Digital Multimeter if you want to.A vacuum tube voltmeter is a must for working on tube equipment. The more basic, lower impedance, VOM Volt Ohm Milliammeter is much more suited to transistor circuits than tubes. The input impedance of a VTVM (or a DMM) is 10 or 11 megohms. Once again the source is eBay.
Tube ManualYou can't get very far if you don't have a tube manual. As before look for them on eBay. Most of the time you will find yourself without a schematic diagram of what you're working on. By studying these pages you can gain familiarity with the various circuits so all you need is a tube manual to tell you which pins are the heater, cathode, grid(s), and plate. Many times you can figure out what is wrong and fix it with no more equipment than this.
Tube TesterA tube tester is somewhat of a luxury. Very handy and a time saver but not absolutely necessary. You can test the heaters using the ohms scales on a VTVM, DMM, or VOM. You can test tubes by substituting another one of the same or equivalent type. If you want one and have the bucks -- do I need to say it?
If you want to build the projects on this site you need the following
- A soldering iron.
- A tube manual.
- A source of old parts.
- A breadboard.
- A power supply.
- An audio amplifier.
A soldering iron.You can't build any electronics without one. The 20 and 25 watt kind for PC boards are a little light for soldering on terminal strips and tube sockets. You don't want one of those 400 watt monsters designed for soldering a fender on a car, either. 150 is still a little large. What I recommend is something in the range of 50 to 100 watts. If you decide to buy a soldering gun on eBay be sure you can get or make tips for it. It will be a useless museum piece with out them.
Tube ManualYou can't get very far if you don't have a tube manual. As before look for them on eBay. I will always give you the pin numbers but if you want to make a tube substitution such as a 6SN7 for a 12AU7* you will need a tube manual to know the pin out of the substitute tube.
* You really could make such a substitution with little change in circuit performance. The reason why you might want to do that is if you had a lot of 6SN7s and no 12AU7s.
A source of old parts.If you're lucky you have a stock of parts you have been hanging on to for years. If not you will need to buy them. My favorite place when I need something I don't already have is (not what you think) Antique Electronics Supply. Look at my links page for more.
Items 4, 5, and 6.You can build items 4, 5, and 6, from the list above by following articles on this site. If you would rather you can buy power supplies and amplifiers on eBay. You can't buy a breadboard there, you will have to build it.
* In keeping with the vintage of the information on these pages I do not use hertz, kilohertz, or megahertz. Instead I use cycles, kilocycles, and megacycles. One cycle = one hertz. That's the way we did it when I was young, sonny.
- Isolation Transformer.
- Metered, Variable Voltage Transformer (Variac).
- 2 VOMs.
- 2 VTVMs.
- High precision DMM.
- R F Signal Generator, Modulated.
- Sine wave oscillator.
- Harmonic distortion analyzer.
- Various low and high voltage power supplies.
- AC Voltmeter; voltage range down to 1 mV and frequency to 1 Mc* or higher.
- Sine, Square, and Triangular wave function generator.
- Frequency counter.
- Q Meter.
- Impedance Bridge.
- Dual trace oscilloscope.
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This site begun March 14, 2001
This page last updated September 5, 2003