Why do most car radios have 6 preset buttons?

The answer is to do with 'Subitizing' - identifying quantities at a glance rather than counting. Most people can easily identify six items if ordered (e.g. in a row as the buttons are - or as two rows on a dice face). Seven buttons would make it too tricky to locate a station.

1. How do push button radios work?
2. What is scan button on radio?
3. What does the scan button do?

How do push button radios work?

The push buttons each contained an inductor (the L part). Pushing the button in released all the others and connected only that inductor into the LC resonant circuit. Each button had a fearfully complex and delicate set of switch contacts to facilitate this.

What is scan button on radio?

Scanning is a way in which a radio can be configured to monitor or receive more than one channel / group of users. It is a very simple system (largely outmoded by digital radio). The radio will have a button or scan control which when set will cause the radio to sequentially listen to each channel in the Scan list.

What does the scan button do?

The Scan button can resolve intermittent connectivity issues between the computer and the monitors.