I figured I have to back my statement up:

from: PDF page #1: https://www.desmith.net/NMdS/Electro...ion%20V4.1.pdf


Use this procedure to test and calibrate the Hickok
Model 539C mutual conductance (AKA
transconductance) tube tester. Except as noted, all
of the readings are taken with a 1000 ohms per vol
t
meter. If an accurate 1000 ohms per volt meter is n
ot available a modern high impedance analog or
digital voltmeter can be used with appropriate shun
t resistors in parallel with the input to simulate
proper loading. The following resistor values shoul
d be used: 10 volt scale use 10K, 50 volt scale use
51K,
250 volt scale use 250K. All resistors are 1/2 watt
5% carbon composition. Calibration will be easier
if
you supply AC power through a constant voltage regu
lation type transformer to do the tests, but this i
s
not essential. Recalibrate the tester any time eith
er rectifier tube is replaced. The correct type #81
(#63
for 230VAC mains) fuse lamp must be installed in th
e tester or false readings can result.