TUBE TESTER REPAIR—FAQ
Why should I have my tube tester restored and calibrated? Most tube testers are 25 to 50 years old at this time. They suffer from aging components such as capacitors and resistors. They may also suffer from past repairs that were not performed correctly. Contacts oxidize creating poor connections, and analog meters stick due to dirt and corrosion. Analog meter movements may change in sensitivity causing further errors. These types of problems need to be corrected to provide the user with a useful and reliable instrument. “As found” tube testers are virtually never accurate or reliable—but it would be unreasonable to expect something so old to function properly without some specialized TLC. When my tester is restored and calibrated will it agree with other testers? Tube tester designs vary and some read in micromhos and others on a numerical scale. It is important that your tester be calibrated to correctly identify a weak, a marginal, and a strong tube. These readings are all relative to the design of the tester itself. In general, testers of the same model will agree on most tubes quite closely—say within 10%. Comparing readings between two different types of testers is only relevant if you know the reject points for the tube being tested for both testers—as they will probably be different. You will get a report back on your individual tester showing how it tested a series of reference tubes after calibration. If you want to know more about how different models compare—read my article on the Testing The 12AU7. Can you work on my tester? My focus is on preserving American made equipment. High quality testers by brands like: B&K, Heath, Hickok, RCA, Sencore, Triplett, and Military testers are what I usually work on. I don’t work on foreign testers or TV2 military units. How much will the work cost? The cost to restore a tester will range from about $100 to $500, depending on the complexity of the machine, and the parts required. A tester like a Hickok 600A would be in the $100 range, and the KS CardMatic would be closer to $500. The Hickok 539C would be in the $250 range. Many hours of careful work goes into a restoration, and you are guaranteed to receive your tester back working properly. Prices do not include return shipping. How long will the work take? Most jobs can be completed within 2-3 weeks but this depends on the present load in the shop.
How should I pack/ship the tester? Careful packing is mandatory! Place some bubble wrap or other padding inside the case to protect the meter (s), and make sure there is nothing loose inside to move around and break things. DOUBLE BOXING IS STRONGLY ADVISED. Your package will probably be dropped on the way, so pack accordingly. If your packaging is not what I consider adequate, I may have to charge to upgrade it. We don’t want the repaired tester damaged in return shipping. Where do I ship the tester? My shipping address is: Chris Haedt G. 8467 South Irish Road Grand Blanc, MI 48439 Please advise by email that you are shipping the unit in. Be sure to note any special problems—like “octal socket does not work and pilot light is out” or “tests high on all tubes”. What if my tube tester cannot be repaired? Sometimes testers have problems (like open or shorted power transformers) that cannot be repaired—at least such repairs are not practical. In this case we may discuss a trade in deal, or you may be charged a nominal fee such as $25 for looking over the machine. Do you sell testers? Yes, I generally have about a dozen restored testers in stock. These are available for sale and trade-ins are taken. I also have manuals for most common models in stock. What is your level of experience? I have restored hundreds of testers and written articles for the Hickok website. I regularly contribute to the Antique Radio Forum, Test Equipment section, Audio Asylum Tubes Section, and answer many questions on tube testers. My work is recommended by: The Boca Electromagnetic Lab, Antique Audio, Antique Electronic Supply, SND Tube Sales, and others. Chris Haedt August 2002 chris@airpump.com