sam. 09 octobre 2021

HP 34970A Data Acquisition Unit - part 6

Quick follow up; I recently got back on this project to try to complete it and fix remaining problems.

The source code for the firmware is available here:

https://hg.sr.ht/~douardda/hp34970-firmware

The Kicad project is available here:

https://git.sr.ht/~douardda/hp34970-pcb

Making the USBDevice work …

sam. 07 novembre 2020

HP 34970A Data Acquisition Unit - part 5

After a loooong pause on this project, I have recently been able to work on it again. In the previous post in this series, I've started to implement a replacement board prototype based on a an NUCLEO board and an SSD1322-based OLED display.

Meanwhile, I have also almost completely described …

jeu. 17 octobre 2019

EIP 545B RF Frequency Counter - Firmware

This part will focus on the analyze of the firmware I made so far, in order to fix a few issues I have encountered in my unit, as related in previous previous part.

It will be updated as I make progress on disassembling and understanding the firmware.

Original Firmware

The …

mar. 28 août 2018

EIP 545B RF Frequency Counter - Part 6

Band 3 Sensitivity

I have been trying to figure out a bit more about the sensitivity problem described in part 3.

The main problem remains the first YIG sphere that has fall off the holding rod. I have tried to manipulate it with thin wood stick, under my cheap USB …

ven. 20 avril 2018

HP8662A Synthetized Signal Generator - Part 3

This is the part 3 on my series about my HP 8662A Signal Generator, and is about the third main problems I found with this unit, as evocated in part 2: Error 04 is lit and there are some very unpleasant spectrums at some frequencies.

Low Fequency Section

If the …

jeu. 12 avril 2018

HP8662A Synthetized Signal Generator - Part 2

This is the part 2 on my series about my HP 8662A Signal Generator. After fixing the PSU, several more problems needed to be addressed:

  • a few sloppy keys on the keypad,
  • the know did not work at all,
  • and more importantly, some very unpleasant spectrums at some frequencies (covered …

sam. 24 mars 2018

HP8662A Synthetized Signal Generator - Part 1

I recently pulled an HP 8662A I bought a while ago from my cellar. I don't remember exactly in what condition it was advertized when I purchased it, but it was most probably advertized as non working (otherwise it would have been cheap enough, more, what the fun in buying …

mar. 27 février 2018

EIP 545B RF Frequency Counter - Part 5

Thanks to HighPrecision, I've been able to get a copy of an old version of the EIP documentation "Additional Service Information for 5XX CW Counters". It's unfortunately unavailable online, still, it contains a lot of valuable information.

The part dedicated to verifying the Band 3 Microwave Converter (A203) is as …

jeu. 15 février 2018

EIP 545B RF Frequency Counter - Part 4

This part is about my attempt to modify the firmware to "fix" the problem of weird intial setup: a -160MHz offset and a resolution set to 5 digits.

In the previous part, we figured some probable spots in the firware where these default setup configurations might be set.

EPROM checksums …

ven. 26 janvier 2018

EIP 545B RF Frequency Counter - Part 3

Default settings

One of the annoying thing with this 'SPECIAL' edition of the firmware are the default settings:

  • Frequency Offset -160MHz
  • Resolution 5 digits

One of my goals while disassembling the formware was to 'fix' these defaults settings. I was wondering wether they where located in an undocumented part of …