Arco Electronics was a leading supplier of trimmer capacitors. Trimmer capacitors are variable capacitors used for calibration of equipment and accessed by professional technicians. They are used to set frequencies in the circuit. They are commonly used in various RF circuits, applications include, tuners, crystal oscillators and filters.
Arco Electronics types include variable compression mica trimmers and mica padders.
Types 40, 42 and 46 were made in 3 types:
These are rated at 175 working DC voltage and variable capacitance ratings 2.5pF - 1400pF
Example: PC-428 175VDCW / 350VDCT 70pF-380pF
Arco Style 30 and 30M are variable compression mica padders - they are enclosed with a ceramic base to protect the plates and mica film.
They are rated at 250 working DC voltage type 30 and 500 working DC voltage type 30M
Example: type 304M – 500VDCW / 1000VDCT 500pF -100pF
Arco trimmer capacitors can be found in communication equipment such as aerospace transmitters, mobile radios, and CATV amplifiers.