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Azur Electronics

I bought the HP 8175A Digital Signal Generator 'spares or repair' unit on eBay UK for £21. The 8175A originally cost $10,050 in 1986. I wanted the Signal Generator to use with my HP 1630D Logic Analyser. This unit has Option 001 Fine Timing Board $1,100 and Option 005 Set of TTL/CMOS Pods $4,950. A total cost of $16,100.

Front Panel showing push-button controls
Rear Panel showing Pod connections
July 2014

Downloaded the Operating and Programming Manual, however the Operating and Service Manual was not available, but thanks to Nick I now have a copy. The Service Manual is essential for any refurbishment work.

Taking off the top cover showed that some screws were missing and some loose coax cables inside. There was a fair amount of dust especially around the fans. Decided to strip it all down to assembly level and inspect everything before powering up. For details see Repair HP 8175A Digital Signal Generator.

The 8175A now powers-up and passes all its self-test routines. Amazing after nearly 30 years and just shows the quality of HP test equipment.

Start-Up Configuration Display

The 8175A provides parallel and serial data with programmable patterns and pattern durations. HP-IB is included.
Number of Channels: 24 parallel, 2 serial.
Bits per Channel: 1024 parallel, 8192 serial.
Max NRZ Bit Rate per Channel: 50Mbit/s parallel, 100Mbit/s serial.
Programmable Pattern Durations: 20ns to 9.99s range, 10ns resolution.
Fine Timing Option 001: 100ps delay resolution on 4 Channels.
Output: TTL or ECL.
Interaction with DUT: 8bit Trigger, 8 Flags.

Pods and lead sets
Option 005 includes 4 off HP 15462A TTL/CMOS Pods and 1 off HP 15463A Trigger Pod , both with their Lead Sets.

One of the HP 15462A TTL/CMOS Pods and its Lead Set is missing, except for its connecting cable! The HP 15463-63201 Lead Set is missing for the HP 15463A Trigger Pod. So need to find replacements, please Contact Me if you have them available.

In addition, there is 1 off HP 15461A ECL Pod with its Lead Set. This cost $800. 
Normally 5 off HP 15408A Plug-On Grabbers with Ground Leads were supplied, for some reason I have 7. Up to 40 are required for multi-channel use. 

Various other Adaptors were available, see page 13 of the Operating and Programming Manual.

Now need to work through the Operating and Programming Manual (only 204 pages) to learn how to use this signal generator.

November 2016

Checking all the specialist batteries in my test equipment, see Batteries In Test Equipment. The 8175A has a 2.4V 0.11AHr NICAD Battery on A20 Assembly, Reference BT1, Part No 1420-0251. Made by GE Part No K02A113AA-GT1 8621.

A replacement battery 2.4V 0.35AHr NiMH was fitted.
The 8175A configuration is saved in RAM. The 8175A needs powering up occasionally to charge the battery.  

October 2019

Working through the Operating and Programming Manual: Chapter 1 General Information; Chapter 2 Installation; Chapter 3 Operating; Chapter 4 Performance Tests.

Front Panel Connectors
EXT INPUT is for a signal input to start and stop data cycling. +9.99V to -9.99V 
±20V max 10KΩ I/P Z.

TRIG OUTPUT, OUTPUT A and OUTPUT B are not connected. They are intended for Option 002 Waveform Generator. This adds the A70 Dual Arbitary Board 08175-66570 which cost an extra $3,456.

Rear Panel Connectors and Switches
EXT REF replaces the internal crystal timing reference with a 1MHz ±0.01% TTL signal ±20V max.

EXT CLOCK replaces the internal clock with a dc to 100MHz TTL signal ±20V max.

TRIG OUTPUT B not connected. Intended for Option 002 Waveform Generator.

The 8 DIL Switches need to be set: 1 to 5 at '0' (not using HP-IB); 6 at '1' for Extended Self Test; 7 at '1' for Master unit; and 8 at '0' for HP-IB Controller.

Chapter 3 is very detailed and shows how powerful this Data Generator is especially with all the variable data patterns available and programming routines, which are intended for testing microprocessor based systems.

Unlike the HP 3762A Data Generator and HP 8018A Serial Data Generator which are both 50Ω outputs; the 8175A provides TTL or ECL level outputs with up to 24 channels in parallel mode, or 2 channels and a clock output in serial mode. In addition the DUT (Device Under Test) can provide various trigger inputs and receive various flag outputs.

The HP 8018A Serial Data Generator can be used as an external clock source which facilitates a continuously variable data rate of dc to 25MHz approx.

Parallel Data Channels
This is a very useful TTL/CMOS signal generator providing up to 24 channels of data, with either an internal or external clock source. Fairly complicated to setup so read the Operating and Programming Manual.

Still need a Pod, Lead Sets and Grabbers to complete this!

August 2020

I would like to add the Option 002 which is the A70 Dual Arbitary Board HP 08175-66570, so please Contact Me if you have one to sell. See below.

Also still looking for a TTL/CMOS Pod HP 15462A, 2 Lead Sets HP 15463-63201 and some Plug-On Grabbers with Ground Leads HP 15408A.

Maybe it will be easier to buy another complete 8175A. See below.

The April 1987 issue of the Hewlett Packard Journal has two very informative articles on 8175A: Digital Signal Generator Combines Digital and Analog Worlds; User Interface and Software Architecture for a Data and Arbitary Waveform Generator.

March 2022

Bought a 2nd HP 8175A, this one has Option 002 Dual Arbitary Waveform Generator plus Option 004 4 off HP 15464A TTL Pods (different to the previous HP 15462A TTL/CMOS Pods) and 1 off HP 15463A Trigger Pod, all complete with their Lead Sets.

Also included were 9 off HP 15408A Plug-On Grabbers with Ground Leads and 11 off HP 15429A 5x2 Solder-In Receptacles.

The Options List for the 8175A is quite complicated and expensive. Option 002 cost $3,465 and Option 004 cost $3,005.

This is a later unit with S/N 2948G manufactured circa 1989.

Downloaded Operating and Programming Manual for Option 002. The Service Manual HP 08175-90001 has information for Option 002 at the end, along with Change Notes.

Powered-up ok, normal and extended self tests ok, quick run through of functions and all appear to be working.

Decided to strip-down, check everything, clean-up and reassemble for testing.
For details see Repair HP 8175A Digital Signal Generator.

... more to follow ...