Russian Microwave Signal Generator G4-80 Teardown

[Yansi]

Hi!

I have just borrowed a few pieces of these Russian microwave generators from the G4 series. This one is G4-80, tunes from 2.56 GHz to 4 GHz. I plan to use these for some MW experiments, until I spare some money for somewhat decent RF generator.

I need to modify the machines a bit, at least with a N output connectors and IEC mains inlets.  So while I am at opening the units up, I]d like to share a few pics with you, as I think these are a brutally awesome pieces of electro-mechanical engineering. Also, they are in very decent shape inside.

By the way, the unit seems to be manufactured 1978-1979. Not that old, actually.

The unit looks like this:


I was stunned to find vacuum tubes inside, when I removed the side cover:


Then I managed to remove the covers (was a bit tricky, screws well hidden):


Look at this awesome mechanically tuned cavity linearizing mechanics! A metric shit ton of set screws!


Don't know what for these screws are, maybe linearization of the mechanical attenuator. Goes down to -190dBm (at leas that's what the dial says).


Huge precision potentiometer:

[technogeeky]

I have never seen one piece of equipment have so many parts I can't even begin to recognize. That golden-ratio spiral... device... is pretty amazing. I'd love to hear more about this as you decipher things!

Lastly, is the panel/heatsink/back wall of the device bowed or cracked? It seems like it has a large overall bend in it...

[Yansi]

Well, that's an optics distortion of my camera, when taking macro photos with zoom. (I have to do it this way, otherwise the photoflash will make nasty spot over exposures).

Nothing is bent and the unit should be fully functional, apart from some broken cranks on the front panel. Haven't tried connecting it to the mains yet. I have quite some respect for the Russian electrolytic caps. They sometimes explode with one hell of a BOOM, if not being careful enough 

I have also noticed one more vacuum tube. It is being heavily heatsinked at the back side, top left on the overall photo.

I am hesitant to tear it apart any more, as I am afraid I would not be able to restore it to its original state.

[bjcuizon]

I love those analog dials and rotating number frequency/amplitude indicators. 
Nice teardown!

EDIT: Oh, yeah...those connectors are weird as.

[Yansi]

Will be interesting to test how precise they actually are, once I modify the connectors on that machine. 

[rsjsouza]

Pretty nice photographs, thank you for sharing! The green goo is ugly as heck (even on the main transformer), but it seems to have been holding quite well throughout the years.

Is it my impression or there are four vacuum tubes on it? Two near the Nautilus' shell and two at the top left?

Do you know what is the square box at the right-center of the overall picture? Is it a capacitor?

Also what is the transparent square at the right-bottom and near the panel and the large orange cylinder under it? Are they a variable capacitor and resistor respectively?

[Yansi]

I think the most ugly part of that thing is that fucking smell inside! The thing has no vents anywhere an those few decades of heated environment inside, with all the plastics, colors, gunks and lubricating shmoo is one hell of a nasty smell.

Yes, 4 tubes at least. The fifth most probably being the klystron or whatever lies in that tuned cavity. I doubt there is any other semiconductor. Need also to check if there are any germanium transistors.

The clear acrylic thing is the calibration meter mechanical guts. See the front panel photo. No idea what the orange cylindrical thing is. It ends with an RF connector on the front panel (KONTROL MOCNOSTI - output level check).  Guessing, there might only be a RF detector inside that cylinder?

The khaki box is a capacitor, probably metalized paper or any similar.

I will take more photos when I will be back home. Also will open up the other generator to see, how much different that one is. (it is the lower band, I think somewhere 1.2GHz up to 2.56GHz)

Y.

[Safar]

If you interesting this is zip file with scanned pages from manual and schematics. But in Russian of course
http://www.astena.ru/DOWNLOAD/g4-78_g4-83.zip

[cdev]

Wow, they don't make them like that any more!

Yansi, please be careful. Weird smells sometimes indicate unsafe materials.

[Yansi]

Thank you Safar for the documentation. Will have a peek inside.

Yeah, I know that weird smells may be unsafe. But I think the most dangerous things here are the almost half century old russian electrolytic capacitors.   

H.

[razberik]

They dont have overpressure vents. They explode like a grenade.
Old serviceman tell stories they went for repair russian TV (Rubin, Selena, ...) when customer said "some POP sound" and they pour out remains from TV.

[TerraHertz]

Wow, that is some impressive mechanicals. It almost looks like you could remove all the normal electronics, and it would still approximately work. (Just kidding.)

Definitely the highest density of calibration trimmer screws I've ever seen. Hey, why don't you turn some of them at random, just for fun?  Go on, you know you want to.