This is a government (US Army) surplus RF/VHF signal generator. The SG-1144/U provides continuous wave (CW), amplitude modulated (AM), frequency modulated (FM), and square wave modulated signals in the frequency range of 50 Kilohertz (KHz) to 80 Megahertz (MHz) with an output level range of – 127 to +10 dbm. The output is calibrated, metered, and levelled across the entire range of frequencies and levels. The RF signal can be internally and externally amplitude and frequency modulated. I purchased this instrument at a hamfest (amateur radio convention). The unit had one problem when I purchased it. The frequency readout was defective and the failure was caused by an operational amplifier. Later on, one band went out because of a bad solder connection. Also, a tantalum capacator on one board of the A2 unit power supply shorted out. The blue tantalum capacitor in the picture below replaced the shorted one.
Several years later, another tantalum capacitor in the A2 power supply unit shorted out. You can see the burned and blackened capacitor in the picture below.
Below is a picture of the all of the tantalum capacitors replaced with either an electrolytic capacitor (2 each) or a blue tantalum (2 each).
Below is a picture of the burnt tanalum capacitor and the other three original capacitors. The right center capacitor is blacked because it was located next to the one that burnt.
All of the subject capacitors are 10 uF capacitors and are connected to either the input or output of a voltage regulator. The original input capacitors are rated at 35V but the original output capacitors are rated at 16V. It is interesting to note that both failed capacitors were the ones rated at 16 V. The replacement capacitors are rated at 50V for the electrolytics and 35V for the blue tantalums. It appears the original 16V tantalum capacitors may have been underrated as to their working voltage.
All in all, the repairs have been minor and the instuument works well - especially for repairing my antique radios. Below are the specifications for this instrument.
