Bad form to reply to one's own post, but nevertheless...
In my write-up of the 'half restoration' of a Sky Queen chassis, I asked how to measure the voltages around the DAF96: the screen-grid resistor is 4.7 megohm, and the anode resistance 1 megohm. So even many modern digital meters would unacceptably load the circuit and give inaccurate readings.
Solution: a single 100 megohm resistor in series with one of my cheap digital multimeters. I first measured the input-resistance on the DC voltage ranges of the cheap multimeter using another one (
). I found the resistance to be 1 megohm on all of 200mV, 2V, 20V, 200V f.s.d. ranges.
Putting a 100 meg resistor in series with one of the leads then reduces the sensitivity to one hundredth (so 2V fsd becomes 200V fsd), and the imput resistance is now 100 meg (or, 101 meg - but the 100 meg resistor was probably 5% tolerance...).
This allowed readings around the DAF96 with far better accuracy.
I guess if you haven't any 100 meg resistors, ten 10meg resistors in series would do the trick.