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| Marconi 2042 RF Signal Generator teardown |
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| DK3BH:
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 range :) The 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 day ;) And no worries, I took the pictures from the running unit after I removed the sound making extra inside :D What made me happy are the operating hours. And we are talking about 1993 vintage by the looks of it. |
| DK3BH:
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 tbh :) The 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 EPROMs :) In the middle the two Burr Brown DACs for the two independent modulators can be seen. |
| DK3BH:
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 :) |
| DK3BH:
At least I finally found the clunking noise: Its was coming from INSIDE the RF tray |O That 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 :) |
| DK3BH:
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 filters :palm: So 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, |
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