Hi,
I have mentioned the HP 4274A LCR meter several times in my discussion of ESR Meters. I bought a second one today, so I thought I would share tips on buying this instrument and some pictures of the insides.
This LCR meter was manufactured in the 80s, by a joint venture between Hewlett Packard and Yogogawa. So you will see a little different style than HP equipment of the same vintage.
This is a high precision LCR meter 0.1% basic accuracy and 5 1/2 Digits of resolution. With option 001 or 002 you can measure capacitors with a dc bias voltage. The accuracy specifications are fairly complex. The accuracy becomes lower at high and very low impedances. I have attached a section from the Operators manual giving the accuracy.
The particular unit that I have photographed was manufactured in 1987.
Buying GuideIf you do a quick check on eBay you will see that most of the units are reporting Errors. This is quite normal
but can be used to your advantage to get a good price. The unit I am showing here I bought for $250.00
If you plug a unit in with nothing connected, you will get a display like this:
For it to work properly, the Lcur must be connected to Lpot, Hcur connected to Hpot and all four of the BNC shield connected together.
Here is a picture of the same unit with my home made Kelvin leads attached:
Also the Bias selector switch on the back should be set to OFF:
Jay_Diddy_B