Heathkit - IT-3120 Professional FET - Transistor Tester - Audio testing equipment
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Description from the seller
Very rare collectible item!
Heathkit IT-3120 Professional FET / Transistor Tester – Made in USA
For sale is a Heathkit IT-3120 FET / Transistor Tester, one of the finest portable semiconductor test instruments produced during the golden age of electronic servicing.
Manufactured in the USA, the IT-3120 provides fast and accurate testing of bipolar transistors, FETs, diodes, SCRs, TRIACs, and unijunction transistors, both in-circuit and out-of-circuit. It measures DC gain (hFE), transconductance (Gm), and leakage current directly on its large, easy-to-read analog meter.
Designed for professional service technicians and serious electronics enthusiasts, the IT-3120 remains an excellent instrument for restoring vintage Hi-Fi equipment, radios, televisions, and laboratory electronics.
Features
Made in the USA
Portable battery-powered operation
Tests NPN/PNP transistors, FETs, diodes, SCRs, TRIACs, and UJTs
In-circuit and out-of-circuit testing
Direct measurement of hFE, Gm, and leakage current
Large precision analog meter
Original color-coded test leads
Rugged all-metal construction
Collector's Rarity
☆☆☆☆☆☆☆☆☆ (9/10)
The Heathkit IT-3120 is widely regarded as one of the company's finest analog semiconductor testers. Its broad capabilities, durable construction, and historical importance make it highly desirable among vintage electronics collectors and professional repair technicians. Complete, fully functional examples with original accessories are becoming increasingly scarce and continue to appreciate in value.
Heathkit IT-3120 FET / Transistor Tester
Description
The Heathkit IT-3120 is one of the best-known portable semiconductor testers ever produced by Heathkit (USA). Introduced in 1977, it is an improved and restyled version of the earlier IT-121, offering faster operation, improved ergonomics, and the same broad range of semiconductor tests.
Like most Heathkit products, it was sold primarily as a build-it-yourself kit, although professionally assembled examples are also encountered. It became very popular with TV, radio, and Hi-Fi service technicians because it could test many components both in-circuit and out-of-circuit.
Main Specifications
Manufacturer: Heathkit
Model: IT-3120
Production period: 1977–early 1980s
Country of manufacture: USA
Type: Portable FET / Transistor Tester
Power supply: 2 × 1.5 V D-cell batteries
Measurements:
DC Beta (hFE): 1–5000
Collector current: 1 mA to 1 A
FET transconductance (Gm): 0–50,000 µmhos
Leakage current: 0–1 A (multiple ranges)
Tests supported:
NPN and PNP transistors
JFETs
Diodes
SCRs
TRIACs
Unijunction transistors (UJTs)
Testing modes:
In-circuit
Out-of-circuit
Meter: Large analog movement
Dimensions: Approximately 240 × 127 × 200 mm
Weight: About 1.75 kg (without batteries)
Features
Tests components without removing them from the circuit
Built-in transistor and FET sockets
Color-coded in-circuit test leads
Direct analog readings of:
DC gain (hFE)
Transconductance (Gm)
Leakage current
Battery condition test
Rugged metal enclosure
Battery-powered portable operation
The IT-3120 was especially valued for reducing troubleshooting time in televisions, radios, and vintage Hi-Fi equipment.
Performance
Even today, the IT-3120 remains a useful tool for restoring:
Vintage amplifiers
Cassette decks
Reel-to-reel recorders
Radios
Oscilloscopes
Early computer hardware
Its analog meter makes it easy to spot unstable or leaky semiconductors that inexpensive modern digital testers sometimes miss.
How Rare Is It?
Collector's Rating
☆☆☆☆☆☆☆☆☆ (9/10)
The Heathkit IT-3120 is considered rare and highly collectible because:
It replaced the successful IT-121 with a modernized design.
Most units were sold as kits, so surviving examples vary greatly in build quality.
Many were heavily used in repair shops for decades.
Complete examples with the original probes, manual, and factory box are becoming increasingly difficult to find.
It is one of Heathkit's last classic analog semiconductor testers before the company shifted toward newer product lines.
Factory-assembled examples or exceptionally well-built kits with all original accessories generally command the highest prices.
Very rare collectible item!
Heathkit IT-3120 Professional FET / Transistor Tester – Made in USA
For sale is a Heathkit IT-3120 FET / Transistor Tester, one of the finest portable semiconductor test instruments produced during the golden age of electronic servicing.
Manufactured in the USA, the IT-3120 provides fast and accurate testing of bipolar transistors, FETs, diodes, SCRs, TRIACs, and unijunction transistors, both in-circuit and out-of-circuit. It measures DC gain (hFE), transconductance (Gm), and leakage current directly on its large, easy-to-read analog meter.
Designed for professional service technicians and serious electronics enthusiasts, the IT-3120 remains an excellent instrument for restoring vintage Hi-Fi equipment, radios, televisions, and laboratory electronics.
Features
Made in the USA
Portable battery-powered operation
Tests NPN/PNP transistors, FETs, diodes, SCRs, TRIACs, and UJTs
In-circuit and out-of-circuit testing
Direct measurement of hFE, Gm, and leakage current
Large precision analog meter
Original color-coded test leads
Rugged all-metal construction
Collector's Rarity
☆☆☆☆☆☆☆☆☆ (9/10)
The Heathkit IT-3120 is widely regarded as one of the company's finest analog semiconductor testers. Its broad capabilities, durable construction, and historical importance make it highly desirable among vintage electronics collectors and professional repair technicians. Complete, fully functional examples with original accessories are becoming increasingly scarce and continue to appreciate in value.
Heathkit IT-3120 FET / Transistor Tester
Description
The Heathkit IT-3120 is one of the best-known portable semiconductor testers ever produced by Heathkit (USA). Introduced in 1977, it is an improved and restyled version of the earlier IT-121, offering faster operation, improved ergonomics, and the same broad range of semiconductor tests.
Like most Heathkit products, it was sold primarily as a build-it-yourself kit, although professionally assembled examples are also encountered. It became very popular with TV, radio, and Hi-Fi service technicians because it could test many components both in-circuit and out-of-circuit.
Main Specifications
Manufacturer: Heathkit
Model: IT-3120
Production period: 1977–early 1980s
Country of manufacture: USA
Type: Portable FET / Transistor Tester
Power supply: 2 × 1.5 V D-cell batteries
Measurements:
DC Beta (hFE): 1–5000
Collector current: 1 mA to 1 A
FET transconductance (Gm): 0–50,000 µmhos
Leakage current: 0–1 A (multiple ranges)
Tests supported:
NPN and PNP transistors
JFETs
Diodes
SCRs
TRIACs
Unijunction transistors (UJTs)
Testing modes:
In-circuit
Out-of-circuit
Meter: Large analog movement
Dimensions: Approximately 240 × 127 × 200 mm
Weight: About 1.75 kg (without batteries)
Features
Tests components without removing them from the circuit
Built-in transistor and FET sockets
Color-coded in-circuit test leads
Direct analog readings of:
DC gain (hFE)
Transconductance (Gm)
Leakage current
Battery condition test
Rugged metal enclosure
Battery-powered portable operation
The IT-3120 was especially valued for reducing troubleshooting time in televisions, radios, and vintage Hi-Fi equipment.
Performance
Even today, the IT-3120 remains a useful tool for restoring:
Vintage amplifiers
Cassette decks
Reel-to-reel recorders
Radios
Oscilloscopes
Early computer hardware
Its analog meter makes it easy to spot unstable or leaky semiconductors that inexpensive modern digital testers sometimes miss.
How Rare Is It?
Collector's Rating
☆☆☆☆☆☆☆☆☆ (9/10)
The Heathkit IT-3120 is considered rare and highly collectible because:
It replaced the successful IT-121 with a modernized design.
Most units were sold as kits, so surviving examples vary greatly in build quality.
Many were heavily used in repair shops for decades.
Complete examples with the original probes, manual, and factory box are becoming increasingly difficult to find.
It is one of Heathkit's last classic analog semiconductor testers before the company shifted toward newer product lines.
Factory-assembled examples or exceptionally well-built kits with all original accessories generally command the highest prices.
Details
Era
1900-2000
Brand
Heathkit
Model
IT-3120 Professional FET - Transistor Tester -
Multiple models
No
Physical condition
Very good
Number of objects
1
Includes
Box
Year of manufacturing
1977
Weight
2 kg
Functional condition
Tested and working/playable
