See the measurement results in the description and photos.
The tubes were tested on L1-3 tube-tester:
Input parameters: Un=~5 V; Ua=2x500 V; Rn=5.2kOhm; C=4mkF;
Output parameters: Iv>=120 mA; (it is 98% )(Measurement error!?)
It is commonly assumed that the Russian 5Ц4С (5U4S) rectifier is equal to the western 5Z4G, and its true!
The only difference compared to a vintage Brimar is a slightly higher peak inverse voltage at 1400v in stead of 1350v for the 5Ц4С.
The GZ30 is also an equivalent with the same specifications as 5Z4G.
Rated electrical data
Heater voltage, V 5
Variable effective stress of the secondary winding of the transformer, V 2х500
Resistance in the anode circuit, Ohm 4700
Capacitor filter, uF 5
Heater current, A 2
The rectified current, mA 122
The rectified current when the heater voltage 4.5 V, mA 100
Maximum electrical quantities
Most heater voltage, V 5.5
The smallest heater voltage, V 4.5
The greatest amplitude of the reverse voltage of the anode, in 1350
The highest average value of the rectified current, mA 125
The greatest amplitude of anode current, mA 375