[Milsurplus] R-390 vs R-390A

[Ray Fantini]

A last comment on the R-390 A thing, having worked on a number A series and a couple Non-A and have to say that as far as I am concerned the older non-A is a real pig if it's out of mechanical alignment, have spent weeks trying to get them so they work on all the bands. Can do the same alignment on a R-390A in an hour.
The A version has the back adjustment for centering the band switch oscillators and the separate RF/IF slug rack from the spectrum generator is a huge improvement from a maintenance standpoint.
Eliminating the power supply regulator system on the R-390 reduces a ton of heat from under the radio and has no effect on stability so it appears that it was useless anyway, and it used some weird variant of the 6080 that had a 24-volt filament that's only in that receiver so that gave you more unique tubes to keep as spares for the regular 390 along with the 3FT7
At the end of the day I think the regular R-390 was more of an overbuilt and more difficult to maintain system that does not compare with the simpler and easy to maintain R-390A
Would be interested to see production numbers because I am certain that way more R-390A receivers were produced then the R-390 and in no way see the R-390A being a "cheaper" cost reduced version of the receiver that proceeded it but a more improved version eliminating items that were not necessary like regulated power supplies and the addition of mechanical filters and ease of maintenance  for me at least make the R-390A a far better radio.



Ray F/KA3EKH


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