No sé si podría ser una derivación del 75 porque mira que hay Felsas en Ranfft pero ese no. Mira a ver si se parece a este:
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Fig. 1
Fig. 2
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[TD="bgcolor: #FFD2D2"][SIZE=+1]
Felsa 75[/SIZE]
Features
manual wind
sub second
Data
10.5''', Dm= 23.3mm
15/17 jewels
f = 18000 A/h
Balance staff U591
Stem W193
Mainspring / battery
Zf1389, 1.70 x 9.0 x 0.10 x 290mm
Hands
1.40 x 0.80mm
Comments about the data[/TD]
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Remarks
bimetallic screw balance
differences not known between 71, 73, 75-80, 144, 166, 167, 203, 205, 216, 219, 240, 244, 255, 268, 284, 286, 287, 326
family/generations:
71: sub second
86: sweep second
100: sub second, date
131: sub second, 11'''
Example, year: signature; shock device
ca. 1935: 119017, Gothic Watch Co New York, Jar-Proof, Adjusted to Temperature, Patent + No.102795, Made in Switzerland, 17 Jewels - 212498, Pat'd
(Felsa 71)[/TD]
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Un saludo.