You can make one: 600V 1 amp. diode, wired with the anode to the signal source and cathode to the output wire (where you attach your + meter lead) which also contains a capacitor and bleed resistor. Select a meter DC range that exceeds the value of the voltage you will be measuring. Values aren't critical. Bleed resistor is usually in Megohms for discharging the capacitor after the measurement. Capacitor needs to be 600V min. also and enough capacitance to offer a flat line of output voltage to the meter DC inputs......0.47 ufd., 1 kv ceramic would work nicely.
Bottom of the cap and res. are tied to equipment ground (-dc) and the neg. meter lead is attached there also.
The reason why A Digital Voltmeter Attachment is necessary is because the pulses are in microseconds and the rest time is in multimilliseconds. The signals come and go before the meter has time to catch them with out something to store the little pulses and allow them to build up to a readable level. The resistor just bleeds off the capacitor once measurements are finished.
