peeding up the scan/search rates for the Uniden BC-200/205 XLT You will need a small crystal or ceramic resonator in the 600-800 kHz range.

Disassemble the unit to access the microprocessor area.


Slide off the battery pack.


Remove the two screws from the rear of the scanner and the two screws that hold the battery retaining spring at the base. Then remove the spring.


Carefuly pry the bottom of the rear cover from the scanner and remove the cover.


Locate the two small screws at the base of the circuit board and remove them. Gently pull the front panel from the main frame at the base and separate them. If you separate them between the two layers. Remember that for later reassembly; the pins will have to be lined up perfectly before you slip the sections back together. 


Search around the logic/CPU board (Uniden calls it the "MICOM PCB Assembly"), and locate Y-201, which is a little rectangular component. This is the stock 400 kHz resonator. Your replacement can be a bit larger if necessary, but not grossly so.


Carefully desolder and remove Y-201. Put it in safekeeping because you may want it for something else someday.


Install (solder) your newly procured replacement clock resonator, be it a crystal or another ceramic resonator, where Y-201 came out.


Reassemble: Insert top of the front panel into the slot under the volume/squelch control panel. Carefully noting the alignment of the dual in-line connector at the bottom of the board with the mating socket, press the front panel firmly into place. Be sure that the holes at the bottom of the circuit board line up two screws and tighten them


Replace the rear cover by inserting the top of the cover into the slot under the VOLUME/SQUELCH control panel. Press cover into place. Insert and tighten the screws.


Reposition the battery retaining spring (slotted side toward notched hole). Insert the two remaining screws and gently tighten them.


Slide the battery pack into place. Switch scanner on to ensure that the display comes on. If not, the battery may be discharged or the dual in-line connector may have been misaligned during reassembly (step 5). Another possibility would be that the new resonator either doesn't work, is unsuitable, or may have been incorrectly installed. Another possibility (if you installed something greater than 800 kHz is that it's just too fast. 
Assuming that the display comes on, leave the antenna disconnected, and run a speed test. Speed in channels-per-second equals the number of channels divided by the time in seconds. Using a Murata-Erie 800 kHz

Note that the channels must have frequencies programmed into them. "Empty" or 0000.000 MHz channels run faster and throw off the calculation.

In addition to the shortened delay time, the user reports that the panel lamp will "time out". Doubling the clock frequency halves the "light on" time. There is a variable extended delay modification in the "World Scanner Report", to large to duplicate here. Also, in Volume 1, Number 4, Bill Cheek reports that the UC-1147 CPU has the necessary large chunk of memory on board, so you're stuck with 200 channels. You can get the WSR from:

COMMtronics Engineering
PO Box 262478
San Diego, CA 92196

The Scanner Modification Handbook I and II are available from the same address. They're something like $17.95 each + $3 P&H. The WSR is $25 per year.

NOTE : I am not responsible for anything that goes wrong.