The Workman MD-4 external meter is designed to plug into euro style radios that have a 2.5 mm external meter jack on the rear panel such as the Super Star 4900B. Some of the later President radios also have this external meter jack.
The meter works like the internal meter for both TX output & RX signal strength. The adjustment on the front is to calibrate the meter to the radio.
It can also be used to sensitize the meter to indicate very small signal strength changes for radio checks or used to desensitize the meter in fox hunts or tracking down carriers once in close proximity of the source.
The MD-4 has a meter input cable terminated with a 2.5mm plug and meter lamp wires which connect to 13.8 volts. The blue illumination blends in very well with automotive lighting.
It can also be wired to the vehicle dimmer switch on mobile installations. In base station installations the lamp leads can be wired internal to the radio 13.8 volt source.
MD-4 External Meter
The Case Dimensions: 6-9/16″W x 3-9/16″H x 2″D Bottom Feet 3/8″
MD-4 Illuminated Meter Movement In Low Light
Meter Face Dimensions: 3-7/8″W x 1-15/16″H