L3-3 Calibration of the Gm test

I received this procedure from Matts Gustavsson.

Hi Jac

It was very easy, just took 2min.. Not sure the is a L3-1 tester as u have in ur new text. My L1-3 have same rectifier as the L3-3 but that i buy was made in 1971 and i know there are L1-3 made in 1960.. Only difference from my L3-3 is hardwire (no PCB) and 3 stabilizertubes) but really it measure smoother than the L3-3 if its stabilizer tubes i dont know but otherwise its same.. And it was NOS...

I do understand u have a good way to avoid calibration of the oscillator but with this u can check very easy.. U can use the "EISKARTE" if u printed that one its same pins as mentioned but need to make hole for the multimeter for pin 4/1.. just for check how of calibration it is..

Mine were exactly 1397hz and 1401hz but little to high amplitude of 0,48 and 0,495 instead of 0,45 but changing didnt make different measurment..

Hope u find this useful..

Best regards


1) Let the L3-3 warmup for 1 hour to stablize with no card
2) Put pins in 20/I, 26/I, 40/II, and 52/II.
3) Check Netz and Calibration of 250V.
4) Set the "S" switch to calibration mode (points to the right)
5) Put in the multimeters "+" in pin 4/I and "-" to ground connection near netcable.
6) Measure the amplitude (AC Volt) and if needed adjust the left of pots in S bord (start with an "AM.." then russian language
so the amplitude is 0,45V AC
7) Change the function so the multmeter measure frequency and if needed adjust the right pot (start with "4A.." so the frequency is
1400hz (+-50hz)
8) Check number 6 and 7 again for higher precision.
9) Recalibrate the L3-3 (Netz, MKA(meter), 250V, and the "S" to the right marks on the meter.