[daveslash]

DISCLAIMER: This is what I remember once hearing in an ECE class. I was hesitant to post this comment given that it might be garbage, but perhaps someone can help confirm or disprove this.

I once heard that one of the reasons the Soviets continued to use analog systems was that they were "faster, more compact, and more power efficient" [than a digital computer]. This came at the cost of flexibility. For example, an op-amp allegedly can do integration faster and with less power than a digital computer, but the IC can't be reprogrammed. Digital computers have huge benefits, but ones that come at a cost.

Thoughts/input anyone? As I said, I might be completely off base so please nobody take that as anything more than "food for though".

[pjc50]

At 1980s levels of integration, then I'd agree that for many sorts of signal processing it's easier to do it in analog than digital. Especially if all your engineers are trained for analog. In 2014 the situation is the other way round.

Robustness of power electronics is another consideration: tubes are mechanically fragile but not vulnerable to ESD, whereas FETs are, especially during assembly. If their factory process control was poor it would have been easier to stick with the tubes.

[Terr_]

I think the #1 reason was military-logistical: Easy to manufacture lots of them from domestic factories, stockpile at airfields, and replace by hand. Some sources suggest resistance to temperature-fluctuations and EMP were also factors.