February 2022


Some time ago, in September at Marzaglia scrap-fair, I’ve got this EG&G Ortec DSPec table-top multichannel analyzer. My unit had the 5k 10 turn “Helipot” HV selector missing.

I’ve replaced it thinking that was just the only issue with it. I was wrong! This post is about how I finally get it working flawlessy.

An eBay listing…

This MCA seems still quiet easy to find on eBay and available at a “reasonable” price. It’s absolutely worth make it working. If hardware have no fails, how to verify that?

On the rear of the machine there are the to-computer connections:

  • Dual port memory
  • 10base2 coaxial ethernet
  • RS232
  • DSPec back

Using a standard RS232 to USB adapter connected to the MCA revealed that the machine, after 30 seconds after power-on, outputs a test result code. 9600bps 8N1

Picture by Marco Tossini

%001000070 All self-test passed! Trying to issue various comands, the MCA reply as expected and executed. This means that it woks absolutely perfectly. Enabled HV, tested, it works as per manual. You can download the manual with all the commands and reply codes chart here: 761560G dspec

Now it’s time to make it working with ORTEC MAESTRO (VER 5.35) software. The only way to connect it to a PC is using the 10base2 coaxial ethernet port. To do that you can use a 3Com Etherlink III ISA ethernet card or a 10base2 to 10baseT media converter or a switch with 10base2 BNC input. This is the tricky part of the whole thing and what drived me crazy and this is a list of what I’ve found.

  • Maestro needs IPX to work, this allow only the use of Windown 95, 98 and Windows XP
  • 10base2 network should be implemented with proper T connectors, 50 ohm cable and 50 ohm terminations at the ends
  • proper protocol shoul be installed into the windows network interface that you are using an NO IP should be present.

10base2 cable. Two “T” and 50 ohm terminations. Cable should be >60cm long.

The network card I’ve used. It’s ISA but you can also find in PCI flavour or better use a media converter

These are the steps I’ve followed to correctly configure the networking on Windows 98. Yes, I’ve resurrected a vintage computer that have ISA slot and installed Windows 98 in it to do such task only.

Go to windows system settings

Open network settings, install the protocol IPX as per picture

Enable NetBIOS

Set Frame Type 802.3

Set bindings

Obtain IP Address automatically

And voilà… Maestro tool “Configure instruments” find it. The name DSPE-183 vary, you can change it via RS232 command

And now it works with my HPGe detectors.