The Tektronix 015-0058-01 is the power supply for the Tektronix 134 Current Probe Amplifier. It plugs into a standard NEMA 5-15 115 VAC receptacle and provides a full wave rectified nominal 20-25 VDC output to the 134 amplifier. That output is filtered and regulated down to ~14 V in the amplifier. It works from 50 to 400 Hz and 103.5 to 126.5 VAC.
The Tektronix 015-0059-01 was the 230 VAC version of this power supply. This was identical to the 115 VAC version except for the cover, which had the different part number and voltage rating printed on it, and the addition of two series dropping resistors (2 kΩ & 2.7 kΩ, both 3 W) ahead of the transformer primary. Oddly, this 230 VAC version appears to have used the same NEMA 5-15 115 VAC cord and plug. The addition of the two series resistors allows it to work from 207 to 253 VAC and 50 to 400 Hz.
All the manuals show a cord and plug for input AC power. The third and forth photos below show a version with the AC power connector integral to the body. This particular example was built up from parts by Deane Kidd. This may not have been a Tektronix standard at any time.
The DC output connector is a Tektronix design that was unusually fragile. This complete power supply could probably be rather easily replaced by any common "wall wart" with an output of 18-25 VDC. If you're tempted to do this, I recommend replacing the cord on the 134 with a modern receptacle that accepts the existing connector on the end of the "wall wart" connector. This would eliminate the original, but fragile, Tektronix connector. It would be wise to add a reverse polarity protection diode inside the 134 if you do this.
If you happen to have one of these power supplies apart, it might be worthwhile adding some series resistance to the primary, as Tektronix did to make their 230 V version. Add ~40 Ω for each volt that your typical line voltage exceeds 115 (or 230) VAC. This would avoid saturating the core of the transformer due to today's higher line voltage, and also reduce the power dissipation in the 134 pass transistor.