GR-1650B Impedance Bridge

Unfolded beauty

This LCRG bridge is portable and powered by 4 D-cell batteries. It is a nice small enclosure. It looks a lot bigger on the picture. The lid of the box has 4 anti-slip feed and the bridge can be placed in every position you like.

The other side showing the external inputs and outputs

These pictures are made by the seller but I liked them, they are well made, just like the bridge. This one looks like new. It has a sticker telling it has last been calibrated in 1982.

It is a 1% bridge. The (black) A version of this bridge was the foundation for the GR1608A. What made this bridge a bestseller was the fact it has something called orthonull. This is the switch between the dials. It mechanically couples the two dials so you can find the null a bit quicker when measuring lossy components. Normally you get a “sliding null” you move the one dial until it dips, then the other until it dips and so on until you reach zero.

It has L in Ls and Lp, Cs and Cp, Rs in AC and DC and Gp in AC and DC. The difference with the 1608A is the absence of the AC R and G compensation capacitor. But there is a connector on the left side to connect one. After you have used it to balance R or G you write down the G or R value, and if the variable capacitor has no scale you connect it to the unknown and just measure it Wink

Folded for transport

The inside with battery holder

It is still accurate within the specs. The 1650B is black and made a bit more solid. It was more expensive and had things like ceramic switches. But the B version is more user friendly, like the external terminals at the side, out of the way. And the 1650B has a little more possibilities.

The folder from the 1968 brochure

The specs


The introduction

The introduction


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