BC200xlt mod.

[Paul]

Can anyone tell me how to modify a Uniden BC200xlt to receive the
entire 800MHz band, please? Any help at all would be appreciated.
THANKS, Paul

[Dr. Bellows]

This is a multi-part message in MIME format.

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DKiser69 wrote:
>
> >Can anyone tell me how to modify a Uniden BC200xlt to receive the
> >entire 800MHz band, please?
>

> Paul email me and I'll give you all the mods you ever wanted for the BC200XLT.
>
> Don

Why does he have to give you an e-mail address?! Just post whatever you
have!

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BC100XLT & 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.

BC200XLT BATTERY LIFE EXTENSION: Part II

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

---
==============================================================================

BC200/205XLT CELLULAR RESTORATION

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

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.

CONVERT 16 CHANNEL to 20 CHANNEL

I discovered a couple of modifications for Bearcat 175xl.
On the CPU board there are 4 solder pads next to the CPU. Shorting two
of them turns it into a 20 channel scanner (from 16 channel). Shorting
the other two removes 29-54 and adds 66-82. I can program 66-88, but
it will not receive 82-88. But it receives 66-82 as well as my 2006.

MODIFICATION TO RESTORE [xxxxxxxx] COVERAGE TO THE
UNIDEN BEARCAT BC 2500XLT

CAUTION: 1. THIS MOD SHOULD ONLY BE ATTEMPTED BY THOSE FAMILIAR WITH
SOLDERING AND DESOLDERING SURFACE MOUNT COMPONENTS.
2. THIS MODIFICATION WILL VOID THE FACTORY WARRANTY.
3. THE ECPA SAYS LISTENING TO [xxxxxxxx] IS A NO-NO.

NOW THAT YOU KNOW WHAT YOU ARE GETTING INTO, HERE IS THE MODIFICATION:

1. REMOVE THE BATTERY PACK AND ANTENNA.
2. REMOVE THE 4 SCREWS HOLDING THE CASE TOGETHER. (2 BLACK SCREWS AND 2
CHROME SCREWS)
3. CAREFULLY PRY THE BACK OFF OF THE RADIO.
4. PULL UP ON THE METAL BRACKET WHICH HOLDS 2 OF THE 3 PRINTED CIRCUIT
BOARDS. IT WILL COME FREE (ALONG WITH THE TOP OF THE RADIO) FROM THE
LOWER PCB. LEAVE THE RIBBON CABLE ATTACHED TO THE TWO DIFFERENT
SECTIONS.
5. LOCATE THE MAIN PROCESSOR ON THE LOWER PCB: UNIDEN UC-1513A
BETWEEN THE MICROPROCESSOR CHIP AND THE SPOT WHERE THE BATTERY
TERMINALS ARE SOLDERED IN, YOU WILL SEE A GROUP OF 5 (VERY SMALL)
(1/16 WATT?) BLACK RESISTORS. (THEY ALL HAVE "104" PRINTED ON THEM.)
6. UNSOLDER THE LOWER LEFT MOST RESISTOR WITH A FINE TIP SOLDERING IRON,
AND MOVE IT ONE PLACE TO THE LEFT (THE RIGHT SIDE OF THE RESISTOR WILL
NOW BE SOLDERED WHERE THE LEFT SIDE USED TO BE).

PUT IT ALL BACK TOGETHER AND YOU ARE DONE.

SEARCH STEPS SHOULD BE THE CORRECT 30 KHz

Concerning the Uniden Bearcat 760xlt, the mod for the 950xlt does work
to restore lost freq. Disconnect pin 20 of the microprocessor from the
circuit board and connect it to pin 19. I bent the pin slightly and cut
it with the scissors of a swiss army knife then soldered an 1/8 lead
cut from a cap across the pins near the top of the chip. I've yet to
find any problem with this mod.

UNIDEN BC-855XLT MODIFICATIONS
Scope of modifications:
[1] Allow continuous 800 MHz receive.
[2] Increase channel capacity from 50 to 100 ch.

0 1 2 3 4
:------------------------------------------:
| I p p p p p o o o o o o |
:----------| I | | | | | |
| [I] | | | X X <-- CUT |
| [I] D201 | | | | | |
| [I] oooooo | | | | | |
| I d d d d d |
| I------/\/\/\--------|--| |
| |
| ADD 4.7K - 22K Ohm (10K works) |
| 1/4 watt carbon resistor between |
| diode D201 and lower connection |
| of Jumpers 3 & 4 |
| Jumper 3 - 100 ch. Jumper 4 - 800 MHz |
|-----------------------------------------------------|
1. Remove 5 screws from bottom of scanner case.
2. Carefully separate case top and bottom.
3. Unplug connector to the internal speaker.
4. Locate diode D201 and 4 jumpers near edge of circuit board.
5. Cut the 3rd and 4th jumpers near the middle and fold
downwards, insulate leads, if necessary.
6. Connect the lower part of jumper 3 & 4 to one end of a 10K
Ohm 1/4 watt carbon resistor, insulate all exposed leads.
7. Connect the other resistor lead to the lower connection of
diode D201, DO NOT cut any leads on D201.
8. Make sure all exposed leads aren't touching any other
connections, insulate as required, tack in place
with a dab of RTV silicone, or low temp hot glue.
9. Reassemble scanner, make sure to plug the speaker back in.
You should now have a scanner with 100 chs. numbered 01-00,
in 5 banks of 20 ch. and continuous 800 MHz coverage.

BC890XLT
Subject: bc890xlt-800mhz full restore

1. remove all cabinet screws.
2. remove 4 face plate screws and 1 bracket screw at center of main board.
3. carefully depress the outside edges of faceplate shield and tilt down.
4. unplug j4 and j5 and ribbon connectors j501 j502 and j503.
5. remove faceplate and logic board.
6. position board so microprossoe chip is on left and memory battery on right.
7. locate the 3 chip resistors at chips upper right..marked 104 and
carefully desolder.
8. install the chip resistor at the 2 empty pads closest to memory battery.
9. reassemble carefully in reverse order.
10. test by entering freq. around 870 mhz.

MR DIBBS... This is a 2-Meter HAM Radio that I have, and by just cutting one wire, it will transmit on
Business Band (McDonald's - WalMart - Etc.) and VHF POLICE Frequencies!! If you ever buy a Ham Radio,
I suggest this one!

Subject: Yaesu Model FT-2500 Mod
Frequency Expansion Modification

Original Freq. Range: TX (144-148 Mhz)
RX (140-174 Mhz)
New Freq. Range TX (140-174 Mhz)
RX (140-174 Mhz)

1. Disconnect DC Power cable from radio.
2. Remove Top Cover. (5 Screws, 2 on each side and one at center)
3. Remove piece of green color wire. (Between Jumper Pad #8 and ground)
4. Reassmble radio and hook-up power.

(Simple Mod Eh?)--------------759426B47585--

[DL]

Paul wrote:
>
> Can anyone tell me how to modify a Uniden BC200xlt to receive the

> entire 800MHz band, please? Any help at all would be appreciated.
> THANKS, Paul

http://w5gb.nmsu.edu/kc5kto/scanner.html#state
--

Regards,
Dean

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[DKiser69]

The reason I asked Paul to give his e-mail is because if you look at your mime
encoded message the format comes out screwed up. The mod file for the BC200XLT
that I have compiled is 45Kb in size. While it's not huge I don't think it is
proper netiqette to post such a large file to a newsgroup. If you want to
flame me for thinking this way go ahead.

Please note the mod list for the BC200XLT is almost finished in its HTML form
with jpg images of the scanner circuit board. When I get the pages up I will
post here. I hope that the new format will make it easier to understand the
mods

Don

[Dr. Bellows]

DKiser69 wrote:
>
> The reason I asked Paul to give his e-mail is because if you look at your mime
> encoded message the format comes out screwed up.

What are you talking about?! It looks fine to me, and I never encode
anything. It is standard text.