The HP 8443A is a compact, rackable tracking generator and frequency counter designed to work with HP spectrum analyzers; it produces a swept CW output that follows the analyzer marker for easy swept-response and marker‑based measurements, while offering a built‑in counter and stable 1 MHz timebase for accurate frequency readout.

Overview

The HP 8443A Tracking Generator was built as a companion to Hewlett‑Packard spectrum analyzers such as the 8553/8552, supplying a front‑panel RF OUTPUT that either tracks the analyzer tuning or recreates the signal at the analyzer marker for detailed inspection and troubleshooting. The unit combines simple front‑panel controls with a numeric counter display so the marker frequency is shown directly on the instrument, making swept‑response work more intuitive and repeatable.

Key Features

• Track Mode that makes the generator output follow the spectrum analyzer’s tuning, enabling direct swept‑response measurements.
• Restore Signal Mode that provides an enhanced replica of the signal indicated by the analyzer marker for closer examination.
• Integrated frequency counter that displays marker frequency and can also measure external signals via a COUNTER INPUT.
• Adjustable RF output level via a front‑panel dBm control for matching test levels to the device under test.

This particular unit will count from 48 kHz to 208 MHz as a stand alone counter. It is one of the later units, with a 2504A serial number prefix. It has the orange tint LED display.

The inside of this 8443A were very clean, which makes me think that it sat for many years in a warehouse before I purchased it several years ago. Because the display is LED, there is no HV supply and no internal cooling fan.

There are only four (4) aluminum electrolytic capacitors in the unit. Three are in the main power supply and one is in the counter. All the other capacitors are either tantalum, ceramic, mica or film. The tantalum capacitors are Sprague 150D series which was a hermetically sealed solid tantalum type.

The three aluminum electrolytic power supply capacitors showed higher ESR and Dissipation Factor than an equivalent modern capacitor, so I replaced all of them.

I also found that R1 on the A15 rectifier board ran very hot. It was an 18 ohm, 3W, wire wound resistor. The resistor was mounted above the board to provide clearance and airflow. I replaced it with two 36.0 ohm 3W metal film resistors in parallel for mounted for additional cooling.

All the power supply voltages I measured were within specification. The ripple values specified in the manual are very low: <0.2mv or <1.0mv , depending upon which rail is measured. I measured 1.8mv or less on all the rails, using the DVM called out in the manual (HP 3455A).

Testing the other functions of this 8443A will be done when I have restored a display module and appropriate plug-ins.