P6230

The Tektronix P6230 is a passive ×10 (450:50 Ω) probe with 1.5 GHz bandwidth and DC offset capability, intended to minimize probe-loading effect when used on logic circuits.

It can be powered from 7000 series mainframes having LEMO S-series connectors for probe power, or compatible units such as the 1101.

The P6230 is sometimes described as a FET probe or an active probe, however, as the circuit diagram clearly shows, this is not the case. The input signal runs through a 400 Ω resistor and a 1 μF capacitor, terminated in 50 Ω internally (switchable) or externally. The active circuit in the P6230, a standard NE5532 dual opamp, has the function of restoring and offsetting the input signal's low-frequency and DC components, similar to the feed-beside technique used in the 7104 scope and 7A29 amplifier.

The P6230 shares accessories with many other Tektronix subminiature modular probes although the input hybrid is unique. Tip color is yellow, connector end color is blue, part number 206-0279-00. Its end to end resistance is 400 Ω.

Key Specifications

Bandwidth	DC to ≥ 1.5 GHz
Rise time	≤ 230 ps
Attenuation	10×
Input Impedance	450 Ω // 1.3 pF (1.6 pF guaranteed)
Signal delay	8.7 ± 0.1 ns
DC Offset range	-5 V ≤ (V_signal + V_offset) ≤ +5 V
Features	Readout Pin Switchable 50 Ω termination

Links

P6230 @ barrytech.com (incorrectly described as active probe)

Manuals

P6230 Operator's manual (PDF, 155KB)

Prices

Year	1985	1989
Catalog price	$395	$420
2015 value	$870	$800

Pictures

P6230 compensation box
Switchable terminator
P6230 probe tip with alligator clip ground lead
Input hybrid
Probe tip components
Probe-to-PCB adapters
Compensation box interior
Compensation box interior
P6230 circuit diagram
P6230 input impedance graph

Measurements

Rise time measured on a 7S12 with S-52 and S-4 heads, P6230 ground sleeve connected directly at S-52 output (no ground lead)
9.2 * 20 ps = 184 ps (equiv. to 1.9 GHz bandwidth)
Effect of using the "low inductance" ground lead - rise time 400 ps, bandwidth 875 MHz
Using the 250 mm alligator ground lead - severe pulse distortion, rise time ~3 ns (115 MHz)!
Bandwidth vs. grounding, from manual