Back when radio scanners were becoming of interest to radio enthusiasts the available technology was very basic compared to what we have today but for the excited hobbyists experiencing radio scanners for the first time it was cutting edge. Effective frequency synthesizer circuits were not an option, at least a type that could be mass produced to feed the sudden market that had opened up for these new toys.
Early Crystal Controlled Radio Scanners
Regency produced a large range of radio scanners that were all based around separate crystal controlled channels with an option to remove each channel from the scan sequence. These scanners were simplicity in themselves making them very easy to operate even for the non technical radio newcomer but this simple design came with huge limitations.
The amount of memory channels (if you can called them that) where fixed by the number of slots for crystals and changing the frequency of a channel meant buying and replacing the crystal. A good example of this is the basic 8 channel Regency airband scanner in the video below that shows how the user could lock out and manually scan through the available crystal controlled channels.
Courtesy of not2fast4u2c
Regency sold a huge number of these scanners with later models having more channels and wider frequency coverage. Getting hold of one is relatively easy from one of the many online auction sites but due to the way radio communications has changed over the years are far from practical these days.
Building More Flexibility into a Fixed Channel Design
In an attempt at offering the scanner user some sort of Synthesized receiver and remove the cost of sourcing new crystals every time they wanted to listen to a new frequency models like the Regency Whamo-10 radio scanner were produced.
Frequency selection was made by inserting metal combs into the channel slot instead of a dedicated crystal making it much easier to monitor a new frequency. By following a matrix you broke off certain teeth on the metal combs to program the scanner, if this seems a little confusing there is more information in the video below.
Courtesy of Will Phoneman
If you come across one of these for sale ensure it has the book that tells how to configure the combs and at least a few unmodified combs before parting with any cash.
At Least Try to be Grateful!
So next time that shiny new scanner does a good job of frying your brain when you try to program it for the first time just take a deep breath while remembering how cumbersome and limited our hobby used to be.