Scope leads (for Heath scopes!)

[Multi-Volti Devices]

Maybe someone can give you a description of the original leads for reference, btu it's
probably a fairly low frequency 'scope, and the only effect varying the leads/probes
would have would be to vary the interaction between the input impedance (R + C) of the
scope and the impedance of the circuits being tested...this is only a concern to the same
extent it would be with any test equipment.

Typical scope input has 1 Megohm input impedance with a few tens of pF capacitance in
parallel.

10:1 scope probe forms a voltage divider where the capacitance is adjusted or
'compensated' for best square wave response (squarest shape).

With 'flying' or twisted leads, you have 1:1 probe, and no capacitive voltage divider to
'compensate'. Twisting leads results in varying capacitance depending on how many twists
per inch. With a 1 megohm resistive (predominantly) input  impedance, a few ohms more or
less probe/lead resistance won't contribute much inaccuracy (which would be basically
voltage divider effect). Adding 1-10 ohms (10 would be pretty rotten conductor, or so
long that you'd have horrendous noise pickup) lead resistance would add about 0.0001 to
0.001 % voltage divider error.

Murray

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