In May 1951, radio news designed the 220 MHz transceiver for civil defense purposes. This band is selected because it is authorized to be used by the holder of the new technician level operating license. Considering the operating levels of many new amateur radio enthusiasts, it is believed that providing more opportunities for ham with technician level operation certificates will be a way to introduce radio operators urgently needed by civil defense operations.
The main design parameters of the device are to provide reliable communication within 5 miles (8.04672 km). This is enough to cover a small town, or, for a large city, to cover a police area on which police operations are usually based. Lower frequencies can be used for Intercity communications, thereby releasing radio equipment units such as these for communication support in local emergencies.
The core of the circuit is 955 acorn, and the more common microtubules (6j6, 6j5 and 6v6) surround the circuit. 955 is used as super regenerative transceiver. The tuning circuit uses ready-made components, but the capacitor needs to be modified to cover the whole frequency band. If no frequency meter is available, the local oscillator will radiate at 225 MHz in a TV with a 21 MHz if if frequency, allowing the transceiver to be calibrated, the magazine said. In the area with channel 13 TV sound signal, if the sound signal of the TV station is audible, it means that the transceiver is set too low.
The authors report that the device gives a good signal at a distance of 17 miles (24.14 km), which means that 2W power may perform well for its expected 5-mile connecting distance.
Post time: May-12-2021