SETUN itself was an electronically binary machine that used bit pairs to encode ternary digits[1].
In support of your point, of the Soviet computers surveyed in the cited article, six were pure binary, two used binary-coded decimal numerics, and only SETUN was ternary[2].
In support of your point, of the Soviet computers surveyed in the cited article, six were pure binary, two used binary-coded decimal numerics, and only SETUN was ternary[2].
[1] [Willis p. 149]https://dl.acm.org/doi/pdf/10.1145/367149.1047530#page=19
[2] [Willis p. 144]https://dl.acm.org/doi/pdf/10.1145/367149.1047530#page=14
[Willis] Willis H. Ware. 1960. Soviet Computer Technology–1959. Commun. ACM 3, 3 (March 1960), 131–166. DOI:https://doi.org/10.1145/367149.1047530