HP 8640B Part 2: Mains input and rectifier board replacement

Tue, 06 Feb 2024 21:12:29 +0100

Introduction

6 years ago I acquired an HP 8640B that needed work (see HP 8640B Part 1: initial state).

Over the last few years, I managed to clean up the unit cosmetically, but not dive in to it any deeper. Until now.

I recently found some time to work on it again and started looking at the power rails. I knew that (at least) the -5.2V rail had intermittent issues, and had noticed the caps on the AC input needed to be replaced as well.

HP 8640B Part 1: initial state

Sat, 10 Jun 2017 00:00:00 +0000

Introduction

I recently acquired a HP 8640B signal generator. A quick summary of the specs shows why this is an interesting piece of equipment:

500kHz to 512 MHz (option 2 adds a doubler, extending the range to 1.024 GHz)
Available power range is -145dBm to +19 dBm, within +0.5dB across the full frequency range
Extremely low phase noise (less then -130 dBc at 450 MHz, 20kHz from the carrier)
Fine tuning (when in locked mode): >+/-20ppm
Integrated counter, switchable between the internal generator and an external input
FM and AM modulation
Beautifully engineered (but that’s just an opinion)

The retail price in the mid seventies was around 12.000 USD (which in 2017 would be about 90.000 USD).

HP 8640B on Dieter Vansteenwegen / Boxfish

HP 8640B Part 2: Mains input and rectifier board replacement

Introduction

HP 8640B Part 1: initial state

Introduction