Is it possible to replase cathode voltmeter with handheld DMM?

[001]

Hi

The manuals for old equipment say that when setting up, you need to use a cathode voltmeter.
 Is this relevant in 2019? Can I use common DMM?

[TimFox]

Years ago, there were two common analog voltmeters used to troubleshooting equipment:
1.  Passive VOM, such as Simpson 260 in US, that had "20,000 ohms per volt" resistance, due to 50 uA meter.
2.  "VTVM", such as RCA "Voltohmyst", with 11 megohm input resistance, where 1 megohm was located in the probe before the cable to the meter box.
Schematic diagrams often specified which type of meter was used to measure the typical voltages shown on the drawing.
Note that the "VTVM" was better than modern DMMs for measuring test points where there was an AC component, since the resistor in the probe isolated the cable capacitance from the circuit.  For example, when measuring the voltage at a cathode with an un-bypassed cathode resistor (for local feedback), the extra capacitance of the meter cable can possibly start oscillation, which will make a large shift in the DC voltage.  If that be your problem with a DMM, a simple probe extension with a 1 megohm resistor may be needed, with an obvious math correction to the voltage reading.

[Specmaster]

Almost certainly you can, cathode meter offers a input impedence of around 12Meg, much the same as a DMM and generally schematics specified that all voltages are taken with either a meter of 20,000 opv meter (VOM) or a cathode meter which will provide a far greater accuracy and will not load down the DUT.

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[001]

Almost certainly you can, cathode meter offers a input impedence of around 12Meg, much the same as a DMM

Sorry
But what about input CURRENT? 

[Kleinstein]

The input current is essentially measured voltage divided by input resistance. So the 10 MOhms meter would dray some 20% higher current than a 12 M meter.

The point to check may be the voltage range. Modern DMMs are usually limited to some 500-1000 V. For higher voltage it usually needs a separate high voltage probe, that may very well be 100 M or similar, but could also cost more than a handheld DMM.