In article
,
FyberOptic wrote:

So I'm wondering if it's
possible to create some kind of oscillator (LC-based or whatever) to
simulate a crystal for this type of device. It wouldn't be nearly as
accurate/stable of course, but I'm curious if it's possible.

FO-

Yes it is possible, as others have stated.

The frequency of the oscillator is related to the Intermediate Frequency
of the radio. One common IF is 10.7 MHz. As an example, a crystal
frequency of 39.3 MHz would receive either 50.0 MHz or 28.6 MHz
depending on how the radio's Radio Frequency stage is tuned.

Scanners commonly use 3rd overtone crystals in the 25 to 50 MHz range.
Higher frequency crystals are possible, but maybe not practical.
Therefore, the radio will usually multiply the oscillator frequency to
receive the higher bands such as 160 MHz or 470 MHz. What this means to
you, is that a Variable Frequency Oscillator (VFO) that covers 25 to 50
MHz (or whatever it takes, you work out the math) will work for both low
and high bands.

To avoid modifying the radio, you may be able to connect the output of
an external VFO to one of the crystal sockets. The original oscillator
would then act as a buffer amplifier. That is if you are lucky. Bad
luck would be if the original oscillator oscillates at some weird
frequency!

Fred
K4DII