[Hallicrafters] RE: [Boatanchors] Voltage Calibration with 1000 ohm/volt vs 20000ohm/volt meters ?

[Gerry Steffens]

I happened to have two Hickok 6000 and one Hickok 6000A testers open on the
bench, doing calibration.  The calibration document provides data for these
testers for both 20,000 ohms per volt and 1,000 ohms per volt meters.

To demonstrate the range of data, following are data comparisons for two
points:

For B+  190 volts @ 20,000
        150 volts @ 1,000

For a grid voltage  43 volts + or - 0.2 volts @ 20,000
                    40 volts + or - 0.2 volts @ 1,000

A couple of the stiffer supply voltages read the same with both meters.

Circuit design determines the effect of loading on the circuit and therefore
no specifics can be derived.

This situation of input Z has caused trouble for a number of friends and
acquaintances with their shiny new digital meters.  Several have perceived
problems where none exist, simply by comparing schematic data to data
measured with the new meters.

I have made an effort to have calibrated 1,000  10,000  and 20,000 ohms/volt
DC meters so I can duplicate the manufacturer's condition.  If the schematic
does not specify what was used to determine the data, I look for trends (all
high or all low) and check with different meters, including a VTVM.  Digital
meters are a last resort except when calibrating others.  Then I hitch the
two in parallel and calibrate the analog unit from stiff sources.  This is
kind of like using a high quality digital receiver for calibrating and using
rf generators.


Gerry


Collecting & Restoring since 1959
Gerald Steffens P.E.
Oronoco, MN