Modification for Putting BC-200XLT In AM Reception Mode I have come up with a crude mod for the BC200xlt scanner to allow AM reception in the 136 to 174 range. Why would I want AM in this range you ask? well I attend several Air shows during the year and the Thunderbirds use 140 mhz area fregs. As we all know the Uniden switches to FM in this range, causeing very distorted reception (slope detection). Somebody else may have already thought of this idea (you?) but here goes. Break the AIR Trace between dual diode D31 and IC1 pin 8. Connect the center of a single pole - double throw mini switch to the trace leading back to IC1 pin 8. Connect one of the other poles to the trace leading back to D31. This is the "Normal" mode(This just restores what you have cut). Now connect the other pole to the VHI (VHF HI) line at a easy to locate point. This is the "AM" mode. What will happen now is when AM is selected the VHF and VHF air band will all be in the AM mode. UHF and others are not affected. When in the normal mode everything is just like it always was. I have done this mode over a year ago so it's still a cloudy in my memory. But it works like this: The microprocessor sends a high to Q7 to select the AIR mode, by routing the VHI signal around D31 by means of the switch the AM detector is reselected. Normaly D31 blocks out the VHI signal allowing FM in the VHF HI range. I hope my explaination of this mod is clear. It does take some delicate surgery to do. I also hope I haven't duplicated anyone elses idea. Thanks Here is another am mod that I found BC200AM.MOD 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� BC 200XLT AM MODE IN THE 136-174 MHz BAND If you ever attend air shows, this modification might be of interest to you. The Thunderbirds and support crew use AM modeon many of their frequencies, and we all know the Uniden switches to FM in this range, causing very distorted slopedetection of an AM signal. This modification will let youenable AM mode and give your BC 200XLT another feature thatlivens up what many people call the most boring band inscanning! MODIFICATION PROCEDURE ---------------------- 1) Break the AIR Trace between dual diode D31 and IC1 pin 8. Connect the center of a SPDT mini switch to the trace leading back to IC1 pin 8. 2) Connect one of the other poles to the trace leading back to D31. This is the "Normal" mode (This just restores what you have cut). 3) Now connect the other pole to the VHI (VHF HI) line at a easy to locate point. This is the "AM" mode. When AM is selected ONLY the air band will be switched, the other bands are NOT affected in any way. CONSTRUCTION TIP ---------------- If you use the micromini slide switch (RS# 275-409), and drill asmall hole in the back of the unit, you'll be able use a pencilpoint to make the switch. This way the carrying case can still be used. HOW IT WORKS ------------ The microprocessor sends a high to Q7 to select the AIR mode, by routing the VHI signal around D31 by means of the switch the AM detector is selected. Normally D31 blocks out the VHI signal allowing FM in the VHF HI range.