Tube Tester Repair and Calibration
Tube tester calibration and repair of Hickok, Western Electric, Precision, B&K, Sencore, Triplett and other brands of tube testers. I do some Military tube testers, but I don’t do Cardmatic tube testers.
This is a description of the repair, restoration and calibration services provided.
Explore all of our Tube Tester Restorations to see examples of past projects.
Mutual Conductance Tube Testers
Hickok
Hickok tube testers are legendary in the vintage electronics world for their precision and advanced testing capabilities beyond simple emission measurement. Their top-of-the-line models—such as the 750, 539A, 539B, and 539C—are highly regarded mutual conductance testers that provide detailed, accurate measurements of tube transconductance and overall performance. The top-of-the-line models are best for tube matching. Other popular models include the Hickok 600, 600A, 6000, 6000A, and 800 series, all offering mutual conductance testing with robust construction. Known as the gold standard in professional service shops and among serious hobbyists, Hickok testers deliver comprehensive tube testing that far surpass basic emissions testing, making them essential tools for restoring and maintaining high-end vintage audio and radio equipment.
B&K
B&K Precision’s mutual conductance tube testers—such as the 747 and 869 models—are well-regarded for their accurate transconductance measurements combined with ease of test setup. Unlike many testers requiring manual adjustment of multiple rotary or slide switches, these models simplify testing by automating or minimizing switch settings, speeding up the process and reducing user error. This user-friendly design, along with robust construction and precise meters, makes B&K testers a popular choice for technicians and serious hobbyists seeking reliable, efficient tube testing.
Triplett
Triplett mutual conductance tube testers, such as the 3423 and 3444 models, deliver accurate and reliable transconductance measurements with robust construction built for professional and hobbyist use. These testers feature clear, easy-to-read meters and straightforward controls that simplify the testing process. Designed for durability and consistent performance, Triplett testers provide thorough testing, making them valuable tools for tube evaluation and restoration.
Western Electric
Western Electric tube testers are highly regarded vintage instruments known for their precision and robust engineering, originally designed for rigorous industrial and telecommunications use. Models like the KS-15560 focus on mutual conductance testing, delivering detailed, accurate measurements of tube performance beyond simple emission checks. Built to exacting standards, Western Electric testers feature durable metal cases, high-quality components, and clear meters, making them prized by collectors and professionals alike. Their reputation for accuracy and longevity makes them excellent tools for serious tube restoration and testing projects.
Weston
Weston tube testers, including the Model 981, are mutual conductance testers known for their precise and reliable measurement of tube transconductance rather than just cathode emission. These testers provide detailed performance analysis with accurate meters and robust construction. Designed for both hobbyists and technicians, Weston units balance comprehensive testing with straightforward operation. Their solid build quality and dependable accuracy have made them valued tools in vintage electronics repair and restoration.
The service consists of the following:
- Install proper fuse lamps.
- Clean controls and switches as necessary.
- Replace all capacitors prone to failure and resistors as necessary to insure accurate calibration.
- Verify proper meter operation.
- Check and adjust shorts testing.
- Check overall calibration of the tube tester with various tubes – power, rectifier, and pre-amplifier.
- Transformer Plate Winding Impedance Matching for best symmetry between plate circuits on Hickok 539 tube testers—improves accuracy and consistency of test results.
Recommended Options:
- Replace vacuum tube rectifiers. The #83 tube is getting scarce and expensive. I recommend converting to solid state rectifiers on 539 models. Requires some circuit modifications.
- Bias Fuse Lamp Protection to protect the bias circuit from shorts—avoids damage to Bias potentiometer on tube testers without this protection.
- Plate Current Mod allows direct measurement with an external digital voltmeter in place of an ammeter on Hickok 539 tube testers—ideal for precision tube matching and logging.
Services provided at additional cost:
- Repairs to get the tube tester operating properly.
- Replace shorts indicator.
- Replace line adjust potentiometer.
- Replace power cord.
- Replace grid/plate cap lead(s).
- Replace meter.
- Replace rubber feet on case.
Requirements for a tube tester calibration:
- The meter movement should be operational and within specifications. I can source new meters for most Hickok tube testers.
- Bias control working on Hickoks. There are no replacements for the bias pot except a donor tester.
- Transformer not burned out.
- Knobs must be present. I may have some replacements for Hickoks.
- No broken controls.
Calibration starts at $220 for Mutual Conductance tube testers. The Hickok 539 and 752 series of tube testers start at $312 due to their complexity.
Contact me and I can go over your options for repairing and calibrating your tube tester.
Package properly and insure against loss or damage. Shipping damage is not our responsibility. If the tube tester is not repaired or calibrated there is a $65 diagnostics charge.
Use the Repair Form to let me know you are sending your Tube Tester.
Hickok 539C Digital Meters
I can convert your meters to Digital Meters. Digital meters are more accurate and robust, eliminating the overload conditions that burn out analog meters. Contact me for details.
Emission Tube Testers
EICO
EICO tube testers were among the most popular and affordable emissions-type testers of the 1950s and 1960s, widely sold both as factory-built units and kits for hobbyists. Models like the EICO 625, 628, and the larger 666/667 were prized for their simplicity, compact size, and comprehensive tube charts covering a wide range of radio, TV, and audio tubes. While they measure cathode emission rather than full mutual conductance, EICO testers remain highly reliable for quickly identifying weak or shorted tubes, making them a staple on many vintage electronics workbenches.
Sencore
Sencore tube testers, particularly the Mighty Mite series like the TC-28 and TC-136, are known for their rugged portability and ease of use. Designed primarily as emissions-type testers, they offer reliable, quick assessments of tube cathode emission, making them popular among technicians who needed dependable field or bench testers. Their solid construction and clear, straightforward controls helped establish Sencore as a trusted name in vintage tube testing, especially for audio and radio repair professionals.
Heathkit
Heathkit tube testers, such as the TC-1, TC-2, IT-17, and IT-21, were widely popular among hobbyists and technicians for their combination of affordability and DIY appeal. Sold primarily as kits, these emissions-type testers provided a practical way to test tube emission and identify weak tubes without the complexity of more advanced testers. Their simple design, clear instructions, and reliable performance made Heathkit testers a common choice for vintage radio and audio enthusiasts building and maintaining their own equipment.
Triplett
Triplett’s emissions-only tube testers, like the Model 2413, were straightforward, reliable tools focused exclusively on measuring cathode emission. These testers emphasized ease of use and ruggedness, catering to technicians who needed quick go/no-go assessments rather than full mutual conductance testing. Popular in service shops and hobbyist workbenches alike, Triplett’s emissions testers provided dependable performance for identifying weak or faulty tubes across a wide range of applications.
Precision
Precision tube testers—especially models like the 10-12, 612, and 920—are among the most iconic emissions-type testers from the mid-20th century. Renowned for their robust construction, precise meters, and comprehensive tube coverage, Precision testers became a benchmark for hobbyists and professionals alike. They measure cathode emission to quickly identify weak, gassy, or shorted tubes, offering reliable performance with relatively simple operation. Their classic design and accuracy have made them a favorite for vintage tube restoration and testing.
The service consists of the following:
- Install proper fuses.
- Replace resistors in the tube testing circuit related to calibration. Especially carbon composition resistors that drift in value over time.
- Replace capacitors prone to failure and resistors as necessary to achieve proper calibration.
- Clean controls and lubricate push button/lever mechanisms as necessary.
- Verify proper meter operation.
- Verify calibration with known quality tubes – power, rectifier, and pre-amplifier.
Services provided at additional cost:
- Repairs to get the tube tester operating properly.
- Replace power cord and/or fused plug.
- Replace 4.5 volt battery for “Set Testing” operation in Precision tube testers.
- Replace rectifier tubes.
- Replace line adjust potentiometer.
- Replace grid/plate cap lead(s).
- Replace rubber feet on case.
Requirements for a tube tester calibration:
- The meter movement must be operational. I can source most Precision meters.
- The shorts indicator must be the proper one for the tube tester and working. I can source some neon indicators.
- Knobs must be present.
- No broken controls.
- Case not damaged. Ugly cases accepted if not damaged.
Calibration starts at $150.
Precision 920 and 10-12 Meter Replacement
I now have replacement meters for the Precision 920 and 10-12 tube testers. Send your tube tester and I will replace the meter and calibrate the tester. You can extend its useful life by replacing the meter. The most common failure in the old tube testers is the meter. Because new meters are more robust, they can better tolerate incorrect settings of the tester.
The calibration with meter replacement is as stated above for the Emission tube testers.
Meter replacement and Calibration is $318.
Warranty
Contact me and I can go over your options for repairing and calibrating your tube tester.
Package it properly and insure against loss or damage. Shipping damage is not our responsibility. If the tube tester is not repaired or calibrated there is a $65 diagnostics charge.
Use the Repair Form to let me know you are sending your Tube Tester.
