P6032

Tektronix P6032
850 MHz cathode-follower probe P6032 Compatible with 1S1 Produced from 1962 to (?) Manuals Tektronix P6032 Manual Tektronix P6032 Preliminary Manual

Manuals – Specifications – Links – Pictures

The Tektronix P6032 is an 850 MHz cathode-follower probe, intended for use with samplers such as the 1S1, 3S1, 3S76, 4S1, and 4S2. It was designed by Murlan Kaufman.

There is an EC1000 subminiature triode in the probe body, which is why it gets slightly warm during operation.

Like all active probes, the P6032 requires power, and for this reason it has two connectors at the scope end of the cable. There is a four-pin power connector and a 50 Ω GR-874 connector for the signal.

The triode has limited dynamic range, so attenuator attachments are provided that attach to the tip of the probe. These attenuators also reduce the loading of the probe on the probed circuit.

Key Specifications

Bandwidth	≥850 MHz
Rise time	0.4 ns max.
Attenuation	10× to 1000× in 1-2-5 steps with supplied attenuator heads, 3× without attenuator
Dynamic range	±0.15 V × attenuation
Maximum input voltage	±0.225 V × attenuation, de-rated for CW operation for 500× and 1000× attenuator heads
Input resistance	10 MΩ with any attenuator head, 3 MΩ without attenuator head
Input capacitance	3.6 pF (10× head) to 1.3 pF (1000× head), 7 pF without attenuator head
Output impedance	not specified, calibrated for 50 Ω load
DC offset	≈0.5 V (not adjustable)

Internals

The body of the probe contains a clipping line composed of what appears to be 21 mm of RG-174 coax connected to the triode's cathode at one end and open at the other end. The circuit description in the manual describes it vaguely, saying only that, "The clipping line reduces signal aberration to a minimum." Page 40 of the Tektronix Probe Circuits concept book explains in more depth,

The section of 50 Ω coax tied to V1 cathode damps ringing in the high frequency response. The coax is terminated in an open circuit to reflect a short circuit 1/4 wavelength from the termination. Since voltage does not exist at a short circuit, the ringing is damped.

The "V1" in the preceding excerpt refers to V103 in the P6032.

Pictures

External view of P6032 without attenuator attachment
P6032 Schematic
Internal view of P6032 Probe tip connects directly to triode grid, which is a bare wire coming out of the top of the tube. Clipping line runs along the body of the probe to the left of the tube socket.
×20 attenuator tip
Internal view of power supply connector. Signal coax passes through undisturbed.
Display on 545A with 1S1 and P6032. Pulse is generated by Tek 284 tunnel diode pulser driving into 50 Ω load, GR-BNC adaptor and then to the probe using a probe to BNC adaptor. The 10x attenuator tip was used on the P6032. Timebase is 200 ps/div.