Ham Radio 2000 #1

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Text File | 1993-11-04 | 19.5 KB | 433 lines

Newsgroups: alt.radio.scanner From: interpol@casbah.acns.nwu.edu (Interpol) Subject: Uniden Bearcat 200XLT Modifications Message-ID: <1992Mar13.182158.11346@casbah.acns.nwu.edu> Sender: interpol@nwu.edu Organization: Northwestern University, Evanston, Illinois Date: Fri, 13 Mar 1992 18:21:58 GMT Lines: 80 Speeding 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. 1. Disassemble the unit to access the microprocessor area. a. Slide off the battery pack. b. 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. c. Carefuly pry the bottom of the rear cover from the scanner and remove the cover. d. 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. 2. 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. 3. Carefully desolder and remove Y-201. Put it in safekeeping because you may want it for something else someday. 4. Install (solder) your newly procured replacement clock resonator, be it a crystal or another ceramic resonator, where Y-201 came out. 5. 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 6. 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. 7. Reposition the battery retaining spring (slotted side toward notched hole). Insert the two remaining screws and gently tighten them. 8. 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. Note that this Newsgroups: alt.radio.scanner From: interpol@casbah.acns.nwu.edu (Interpol) #Subject: Uniden Bearcat 200XLT Battery Indicator Modification Message-ID: <1992Mar13.185815.15749@casbah.acns.nwu.edu> Sender: interpol@nwu.edu Organization: Northwestern University, Evanston, Illinois Date: Fri, 13 Mar 1992 18:58:15 GMT Lines: 161 Here's some mods to help remedy the 200XLT's low battery indicator/blank out feature, courtesy of Bob Parnass: BC200XLT LOW BATTERY FIXES Troy T. Pummill, N6XMV Here are two small articles from MT. I have not tried these mods, do so at your own risk (i.e. your milage may vary). From Monitoring Times Bob's Tip of the Month May 1990, page 98 BC200XLT SHORT BATTERY LIFE SOLVED Short abttery life--sometime only an hour or two between charges--seems to be the only major complaint amoung owners of the laeading hand-held scanner, the Uniden Bearcat BC200XLT. Presumably, owners of similar sets like the BC100XLT BC205XLT, and Cobra 4030 could have the same prob- lem. Now that is an ailment of the past. It turns out that the batteries were not really at fault; a zener diode which determines the voltage at which the low- battery indicator would come on was defective in some units, causing the circuit to actuate prematurely. Replacing that idode and changing the value of an associated resistor pro- vides the answer. FREE FIX MT contacted Uniden and was assured that they will provide the fix for free, even if the radio is outside of the one- year warranty period. If your Uniden BC200XLT suffers from short battery life, send the radioo along with a brief note describing the ailment, to Uniden Customer Service, 9900 West Point Drive, Indianapolis, Indiana, 46250. As shown in the accompanying diagram, zener diode D203 and resistor R208 are the parts in question. D203 should be about 7 volts and R208 should be 150,000 ohms. These are miniature surface-mount devices on double- sided circuit board; if your radio is under warranty, attemping this fix yourself will void that warranty. -| D203 -|-------////--------;------------|>---------------; -| R208 | HZK3CLL01TR | 150K | | | | | ------------- | | | | | | TK11750 | -| | | (printed | -|------| IC202 | sideways) | -| | | | | | | | | | ------------- | | | SHORT CUT Mark Machcinski of Wyandotte, Michigan, came up with hisw own solution. He simply soldered a wire bridge across diode D203, disabling the low battery indicator entirely. The radio now operates uninterrupted until it blanks out when the abttery level drops to about 4.5 volts. Yet another suggestions from a Canadian reader would bridge the original diode with a 6.8K resistor, defeating the premature recharge signal, yet preventing the battery from too low a discharge. From MT June 1990, page 98 Bob's Tip of the Month BC200XLT BATTERY LIFE EXTENSION: Part II Every time we run a helpful hint on a popular product, some- one find an even more helpful hint! This one disable the low battery cutoff circuit and adds several hours of opera- tion to a single charge. Our lab unit was still going strong after seven hours straight! Uniden will provide the fix for free, but if you're in a hurry and don't mind void- ing your warranty, read on! NOTE: This modification should not be attempted by anyone unfamilier with small circuit oard components. The tools: You will need a small Phillips screwdriver, fine-tip soldering iron and solder wicking braid. The procedure: Remove the battery pack, then the two screws form the bottom spring clip. Carefully pull the rear cover off, bottom first. Remove tjhe two small screws at the base of the circuit board. Pull the front panel away from the mainframe, bottom first. At the bottom of the remaining board--to the left of the speaker magnet--are two blue electolytic capacitors; just above them are two striped components-- one resistor and one diode. Using the soldering iron and braid, carefully remove the two components without overheating the board or damaging the copper traces. When you reassemble the radio, be very carful to note the insertion of the front panel into the slot at the base of the volume/squelch panel. Be especially careful to align the screw holes perfectly, allowing the two rows of fine pin contacts to mate correctly with the socket. If this is not done correctly (and it probably won't be the first time!) no damage will occur, but the scanner display will be blank. Recharge your batteries after 6-8 hours of heavy use. If the scanner dies, recharge it as soon as possible to prevent loss of your memorized frequencies. __ || || ------ | | Voltage Regulator PARTS LOCATOR | | ------ [][][] ___ [___] resistor ___ [___] diode ------ - - - - -- -- - - - - - - - - -- -- ------ capacitors (2, round) Speaker Magnet --- ============================================================================== Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihlpm!parnass - (708)979-5414 ---------------------------------------------------------------------------- | Drew S. Cheng, BA '91 MD '95 | "Compelling, yet tedious...I | | Northwestern University | feel spent, like a man who is | | Medical School, Chicago, IL USA | forced to wear his genitals | | IRC : "Interpol" | like a pendant." | | Internet : interpol@nwu.edu | - Dieter, "Sprockets" | -----------------------------------------| | | Got any anime stuff? | ----------------------------------- Newsgroups: alt.radio.scanner From: interpol@casbah.acns.nwu.edu (Interpol) #Subject: Uniden Bearcat 200XLT Cellular Restoration Mod Message-ID: <1992Mar13.190511.16655@casbah.acns.nwu.edu> Sender: interpol@nwu.edu Organization: Northwestern University, Evanston, Illinois Date: Fri, 13 Mar 1992 19:05:11 GMT Lines: 105 Yet another Uniden/Bearcat 200XLT modification, courtesy of Bob Parnass and other good people: BC200/205XLT CELLULAR RESTORATION Note: It is unlawful to monitor cellular telephone conversations. It is possible to monitor signals from the deleted ranges even without conversion. Simply add 21.7 MHz to the deleted frequency and enter the higher (image) frequency. Reception is virtually identical in strength to that which would be heard on the deleted frequency. The frequencies deleted at the factory may be restored, but the procedure must not be attempted by anyone unfamiliar with electronic circuitry. Grove Enterprises assumes no liability for damage caused by this procedure. The modification will void your warranty. TOOLS REQUIRED: Small Phillips screwdriver, small wire cutters. 1. Slide off the battery pack and remove the antenna from the scanner. 2. Using a small Phillips screwdriver, remove the two screws from the back of the scanner, the two screws which hold the battery retaining spring at the base and the spring itself. 3. Carefully pry the bottom of the rear cover from the radio and remove the cover. 4. Locate the two small screws at the base of the circuit board and remove them. Gently pull the front panel from the mainframe at the base and separate them. 5. Locate the (64 pin quad flatpack) microprocessor IC labelled "UNIDEN UC-1147" and the 10k ohm (brown-black-orange) leadless resistor positioned above the letters "DEN" on the IC. 6. Using miniature wire cutters, cut the resistor body in two without disturbing anything else near it. If the left solder pad comes loose, it may be peeled from the board. Brush or blow away any residue. This completes the restoration. REASSEMBLY 7. Insert the top of the front panel into the slot under the volume/squelch control panel and, noting carefully the alignment of the dual inline 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 with the holes in the plastic standoffs below them. Insert the two screws and gently tighten them. 8. Replace the back cover by inserting the top of the cover into the slot under the volume/squelch control panel; press the cover into place, insert and tighten the screws. 9. Reposition the battery retaining spring (slotted side toward notched hole), insert the two remaining screws and gently but securely tighten them. 10. Slide the battery pack into place; switch the scanner on to make sure the display comes on. If not, the battery is discharged or the dual-inline connector was misaligned during assembly (see step 7). Assuming the display comes on, press: MANUAL, 845.0, E; within two seconds, the frequency 845.000 should appear on the display. Cut this resistor | V [*10k*] [ ] I I I I I I I I I I I I I I I I I I I = = = = = = = = = U N I D E N = = = = = = = = = = U C - 1 1 4 7 = = = = = = = I I I I I I I I I I I I I I I I I I I Pete Simpson, KA1AXY SIMPSON_P@MERCURY.CEO.DG.COM Data General Corp Westboro, MA 01580 (508) 870-9837 "My company doesn't have anything to do with this." that's it.............et. Edward Thomas, N2IHN. P.O.Box 3233 Long Branch,NJ. 07740 UUCP: rutgers!petsd!tsdiag!ka2qhd!n2ihn ---------------------------------------------------------------------------- | Drew S. Cheng, BA '91 MD '95 | "Compelling, yet tedious...I | | Northwestern University | feel spent, like a man who is | | Medical School, Chicago, IL USA | forced to wear his genitals | | IRC : "Interpol" | like a pendant." | | Internet : interpol@nwu.edu | - Dieter, "Sprockets" | -----------------------------------------| | | Got any anime stuff? | ----------------------------------- Newsgroups: alt.radio.scanner From: interpol@casbah.acns.nwu.edu (Interpol) #Subject: Uniden Bearcat 200XLT 136-174 AM Modification Message-ID: <1992Mar13.193440.20576@casbah.acns.nwu.edu> Sender: interpol@nwu.edu Organization: Northwestern University, Evanston, Illinois Date: Fri, 13 Mar 1992 19:34:40 GMT Lines: 39 Here's the last of the 200XLT mods I know of...downloaded off of a local BBS here in Chicago: Modification for Putting BC-220XLT 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 From: BILLY WIGGINS ---------------------------------------------------------------------------- | Drew S. Cheng, BA '91 MD '95 | "Compelling, yet tedious...I | | Northwestern University | feel spent, like a man who is | | Medical School, Chicago, IL USA | forced to wear his genitals | | IRC : "Interpol" | like a pendant." | | Internet : interpol@nwu.edu | - Dieter, "Sprockets" | -----------------------------------------| | | Got any anime stuff? | ----------------------------------- Copied from the QRZ! Windows Ham Radio CDROM