About soviet parts.
I'm also from Russia so I can help you with this.
Don't know how old parts smell in other parts of the world, but I really like smell of old USSR capacitors. I have a big box of them.
In USSR all parts were standardized, everything must be within standards.
Manufacturers marked all the parts with its type, basic parameters and date code. No their own partnumbers. Nothing like, for example, TL494 = DBL474 = KA7500 that are part numbers from manufacturers. The only thing manufacturer could do - leave its small logo on the device.
Type of device is marked in cyrillic. So "K" in "K 50-16" is in cyrillic. This is the type of the device, not manufacturer's name or part number. Manufacturer's logo is often near the device type. Here are
some examples of logos.
"K50" are electrolytic aluminium capacitors.
"K51" are electrolytic tantalum capacitors.
"K73" are metallized film capacitors with polyester isolator.
"K71" are metallized film capacitors with polystyrene isolator.
"K78" are metallized film capacitors with polypropylene isolator.
And so on. All types are standardized, you can
see some types here (Russian language, probably Google translator will help).
"-16" or "-9" is model number of capacitor.
So "K50-16" equals to "electrolytic aluminium capacitor model numer 16" ("K50-16" and "K50-6" were hugely widespread within USSR).
"K50-7" also electrolytic aluminium capacitor but model number 7. And yes, bottom connector is positive and can is negative.
There many types of capacitors with negative on their cans:
K50-3,
K50-12,
K50-20"K73-9" equals to "metallized film capacitors with polyester isolator model number 9" ("K73-9" and "K73-17" are also well know in USSR/Russia).
"MLT-2" is somewhat similar. "MLT" is type of resistor ("metal film resistors", this is old type of marking, not used now, now "MLT" is something like "C2") but "-2" is its power dissipation, not number. So it is capable to dissipate 2 watts of power.
"PP3-43": "PP3" is wirewound one-turn variable resistor with power dissipation up to 3 watts. Yeah, "-43" is not a power dissipation here, it is a model number again.
"CP-5M" is wirewound multi-turn resistor for PCB mounting.
Parameters are sometimes in cyrillic but sometimes not. So "1R5" is 1.5 ohm. But it could be "1.5 Om" as it is on "CP-5M". Capacitance and voltage the same: sometimes in cyrillic, sometimes not. So, yeah, your "K50-16" is 100 uF 50 V cap and your "K73-9" is 100 nF 630 V.
Date code on USSR/Russian parts is not "year/week" it is "year/month".
Btw, soviet electrolytic aluminium caps are crap. They died almost when left the production line. If you got old soviet device first you should do - replace all "silver cans", all of these "K50-6" and "K50-16". They dry out very quickly. But other types are pretty useful.
I don't know about all soviet electronic parts manufacturers, I think many of them closed after USSR fell apart. But I found that manufaturers of parts from your video are still alive!
"MLT-2" resistor made by "
ERKON" (Russia, Nizhny Novgorod).
"PP3-43" resistor made by "
LTAVA" (Ukraine, Poltava).
"K73-9" capacitor made by "
Polycond" (Russia, Ryazan).
"K50-7" capacitor made by "
Novosibirsk components plant 'Oksid'" (Russia, Novosibirsk).
I'm thinking about sending you some components as well, but with descriptions in the note and maybe some beauties as well (military-spec old devices, ICs...).