Interesting little lamps, I guess we bought them from the same seller. I have the other colors as well (blue, yellow, orange and white), those are nice pieces of Soviet lighting history.

I've got some of the blue and yellow ones.

We've just found them, although I can't think of the correct resistor value so we can light them, can you help, Max..?

We've now found the resistors for them nice beefy 5kΩ ones, rated at 5W.

Interesting, such resistor is best suited for your 250 V mains. In my database, I noted that a 47 kΩ resistor is needed with these lamps for 220 V mains, resulting in a 3 mA drive current. 5 W is definitely overkill though, the 56 kΩ ballast resistor dissipates about half a Watt.

We did try a resistor that size, but it got rather hot. Would you know what value would be best for 120V..?

13 kΩ should be fine for 120 V mains I think (I'm assuming an operating voltage of 80 V, so please check that the drive current is around 3 mA indeed).

Thanks, we'll give it a try.