Tonghui TH2822A LCR meter

Today we are unpacking a brand new  LCR meter from a company called Tonghui in China. It was purchased on ebay and took less than a week to arrive.

Chinese market packaging

Chinese market packaging

Model TH2822A- 10kHz max frequency

Model TH2822A- 10kHz max frequency

Accessories included

Accessories included

Four wire test clips included

Four wire test clips included

Closer look- the blades that plug into the meter are just PCB fingers

Closer look- the blades that plug into the meter are just PCB fingers

Warranty card with serial number included. Not sure how good it is outside of China

Warranty card with serial number included. Not sure how good it is outside of China

Test leads , AC supply and a shorting bar incuded

Nice touch- having AC supply allows longer tests without running battery down

Nice touch- having AC supply allows longer tests without running battery down

Threaded insert for the battery door

Threaded insert for the battery door screw

When inserted backwards, you could have reverse polarity voltage present on the terminals. Hopefully, the design can handle that

When inserted backwards, you could have reverse polarity voltage present on the terminals. Hopefully, the design can handle that

On the other hand, the plastic openings are keyed to only let the battery be fully installed the proper way

On the other hand, the plastic openings are keyed to only let the battery be fully installed the proper way

With the unit unpacked and battery in place, let’s power it up:

Nice and bright backlight

Nice and bright backlight

A few capacitance checks versus a reference Agilent U1252A DMM. They are not exactly fair, as we are using a 4 wire setup in TH2822A vs a two wire one with Agilent. The results also depend on test frequency and the test mode you are using- series or parallel. The manual has a selection table based on the value being measured, but I can’t claim to have it always been correct during these tests. First is 470uF Panasonic electrolytic cap. 470uF nominal

Same cap, 100Hz test

Same cap, 100Hz test

Next is a 1uF panasonic

1uF  cap

1uF cap

Sames cap

Same cap

And for something larger: 3200uF nominal cap from a PC power supply:

3200uF nominal

3200uF nominal

But watch what happens when we bump the test frequency- it goes negative?

Same cap at 10Khz test

Same cap at 10Khz test- not sure it should do this !

And now on to ceramics:

4pF ceramic

4pF ceramic, too small for Agilent to measure

62pF- Agilent

62pF- Agilent

62pF- Tonghui

62pF- Tonghui

On to resistance checks, using Voltagestandard’s  DMM Check Plus that comes with four 0.1% precision resistors: 100k comparison

100k nominal

100k nominal -Agilent

100k nominal- Tonghui

100k nominal- Tonghui

10k comparison

10k nominal- Agilent

10k nominal- Agilent

10k nominal- Tonghui

10k nominal- Tonghui

1k comparison

1k nominal- Agilent

1k nominal- Agilent

1k nominal- Tonghui

1k nominal- Tonghui

 100 Ohm comparison

100ohm nominal- Agilent

100ohm nominal- Agilent

100 ohm nominal- Tonghui

100 ohm nominal- Tonghui

Inductor tests- I had no known value ones to measure and no other meter to compare to, so ommiting that functionality for now.

Utility menu. Util button, when pressed for a few seconds gives access to a utility menu with a lot of useful settings:

To beep or not to beep that is the question

To beep or not to beep that is the question

Automatic power off interval

Automatic power off interval

Power up configuration

Power up configuration

Reset to defaults

Reset to defaults

Handy battery voltage meter

Handy battery voltage meter

And now on to a quick peek inside:

Typical pragmatism- why bother with metal inserts on the case screws if they are not used as often as the battery cover one

Typical pragmatism- why bother with metal inserts on the case screws if they are not used as often as the battery cover one

This looks very familiar to anybody who opened a BK Precision BK879 series unit

This looks very familiar to anybody who opened a BK Precision BK879 series unit

TI MSP430F437 and Altera CPLD

TI MSP430F437 and Altera CPLD

All brand name silicon- NXP, TI, ADI. Protection board adds lots of diodes and TVSs

All brand name silicon- NXP, TI, ADI.

Goop under the crystal to keep it in place

Goop under the crystal to keep it in place

Altera CPLD

Altera CPLD

MSP430F437

MSP430F437

Protection board details. Dides and TVSs? abound

Protection board details. Diodes and TVSs? abound.

Another full board view

Another full board view

The USB interface is a simple Virtual com port using Silicon Labs CP2102 chip, with drivers widely available. The interface protocol is SCPI compliant and nicely documented in the user manual.

PC GUI listed 6 COM ports, never mind the one actually assigned to the device was COM8

PC GUI listed 6 COM ports, never mind the one actually assigned to the device was COM8

With the exception of the added input protection board on this meter, the interior is suspiciously similar to a BK 879B from BK Precision.There is a lot of talk of Toghui  company being an OEM for many other brands, possibly including BK over on the EEVBLOG forums. See this thread for more examples. The similarities in the hardware, firmware, menus, PC software and even case design are definitely pointing to the common ancestry between them in the humble opinion of this blogger.

Conclusion: I am pretty happy with the meter. It’s very easy to use, menus and manual are logical and the ranging is lightning quick. The assembly quality and components used are first rate. For about $100 less you get essentially a BK 879B unit minus stateside support and warranty, but with additional input protection and the four wire clip leads.

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5 thoughts on “Tonghui TH2822A LCR meter

  1. I own same LCR meter and I am happy with it, still I am looking for a populated board
    with battery charging circuit, anyway very nice presentation, but I think you should better to choose proper frequency and proper mode on measurement conditions when compare the meter to the other one as it is explained in docs.

    • I guess this illustrates what a first time user would do, before realizing the importance of modes and frequency;) Having never used an LCR meter before, that caught me as well!

  2. Thanks for posting the manual. Couldn’t find it except by registering on the tonghui site and then waiting for registration to be approved. Fail.

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