Marconi 2042 RF Signal Generator teardown - Page 1
Forum section: electronics / testgear

author: DK3BH
author_rank: Newbie
timestamp: January 30, 2023, 08:02:25 pm
content: Hello fellow Voltnuts,I just stumbled upon an interesting bit of kit you also might be interested in to take a look inside.I found it at a local used equipment seller: A Marconi 2042 Signal Generator with 10 kHz to 5,4 GHz Frequency rangeThe unit was in terrible condition. It was a bit dirty on the outside and serval screws were totally worn.When I arrived at my flat, I realised when you moved the device around (which is kinda tricky since it weights around 20 KG), metallic clunking from the inside was audible.Not a good start but the guy sold it to me for a good price and I remembered Daves teardown of a Marconi 2023 RF generator which drew my attention to RF magic back in the dayAnd no worries, I took the pictures from the running unit after I removed the sound making extra insideWhat made me happy are the operating hours. And we are talking about 1993 vintage by the looks of it.

author: DK3BH
author_rank: Newbie
timestamp: January 30, 2023, 08:20:22 pm
content: After removing the top cover I saw why that thing is that heavy:The entire unit consists of two shielding trays, made out of machined aluminium, a linear power supply and a mechanical attenuator.After removing the shielding plate a huge board of DIL IC madness was revealed.The thing seems to be operated by a Intel 80186 processor. I was not expecting this amount of THT components tbhThe PLL section seems to consist of a gate array logic IC and a few components inside the shielding can in the lower left corner.The main applications is stored inside good old classic EPROMsIn the middle the two Burr Brown DACs for the two independent modulators can be seen.

author: DK3BH
author_rank: Newbie
timestamp: January 30, 2023, 08:30:25 pm
content: Unfortunately I found nothing loose, so I needed to remove the entire tray.There are various small coax connectors all around and since the can is really heavy, its really easy to damage them.After removal, a large linear power supply and the second RF tray can be seen.The power supply features a large toroidal transformer with massive capacitors and bridge rectifiers mounted to the side of the chassis.It all feels a bit over engineered and not really refined as some of the R&S and Advantest devices I torn apart so far.The attenuator has its actuator coils totally exposed. But at least we can have a good look at them

author: DK3BH
author_rank: Newbie
timestamp: January 30, 2023, 08:36:58 pm
content: At least I finally found the clunking noise: Its was coming from INSIDE the RF trayThat tray has the logic board on one side, and the RF parts on the other side.So, despite that nice looking "Caution, BeO components" sticker, I needed to take a look inside.After a awful lot of phillips screws, the RF goodness was finally visible.Also a surprising amount of THT components here (for a 5,4 GHz generator at least), but on the RF parts, you can only see SMD parts and distributed filter magic all around

author: DK3BH
author_rank: Newbie
timestamp: January 30, 2023, 08:47:28 pm
content: And yeah, I also found some things you don't want to find inside your signal generator:A few loose screws and an awful scratch across some of the interdigital distributed filtersSo somebody definitely had a hack on that poor thing.I removed the screws and reseated them were they belong (somewhere within the harmonic filter area).The scratch didn't disconnect stuff within the filter area, but a few traces on the perimeter of the PCB were cut. I bridged them and hope for the best.I keep you guys updated if I need to disassemble the poor thingy further or if there are any life signs (despite the display)Cheers,