Subject: PRO51 MOD



There is an interesting test mode in the PRO-51 that,

combined with the direct search feature of the scanner, lets

you pick up out-of-band frequencies. You will have full

access to the 66-88 Mhz ranges as well as the cellular base

range of 869-896 Mhz.



Actually, there are several test modes in the PRO-51 (most of

these comments should be true for any Uniden-made Radio Shack

scanner, such as the PRO-46). I'll describe them first and

then how to take advantage of one of them to get the

restricted frequencies.



There are three data test modes. These modes completely

destroy any frequencies you had programmed into your scanner,

so it's best to use these techniques before you program your

scanner. If you have already programmed it, you'll have to

decide if these new capabilities are worth reprogramming.



TEST MODE 0. Clear the scanner.

--------------------------------

A well-known method of clearing the scanner to all zeros is

to hold down the 2 key, the 9 key, and turn on the scanner.

All frequencies will be lost.



TEST MODE 1. Fill channels 1-25 with test frequencies.

-------------------------------------------------------

Press the 2 key, the 9 key, the L/Out key, and turn on the

scanner.



This fills channels 1-25 with these frequencies:



 1       30.050

 2       40.840

 3       49.900

 4      138.150

 5      162.400

 6      173.225

 7      406.875

 8      453.250

 9      511.9125

 10     108.500

 11     118.800

 12     127.175

 13     135.500

 14      66.450*

 15      76.825*

 16      87.425*

 17     157.800

 18     482.3625

 19      29.000

 20      54.000

 21     806.000

 22     857.200

 23     888.96*

 24     911.500

 25     954.9125



* indicates not within the PRO-51's normal coverage. More on

how to use these in a minute.



TEST MODE 2. Fill channels 1-17 with test frequencies.

-------------------------------------------------------

Press 2, 9, Manual



Fills channels 1-17 with these frequencies:



30.00, 40.00, 50.00, 140.00, 155.00, 170.00, 410.00, 460.00, 510.00, 54.00,

109.00, 118.00, 127.00, 135.00, 810.00, 860.00, 950.00.



There is also a display diagnotic mode.



TEST MODE 3. Display Test.

-------------------------------

Press 2, 9, BAND or 2, 9, MONI.



This put the display in test mode. Every annunciator and

every digit element is turned on in a scan from the left side

of the display to the right. To keep this test mode

continuous, release the buttons before the first scan

finishes. This mode does not affect stored memory. Press any

key to exit this display mode.



Now, if you've decided to try test mode 1, you will find

several out-of-band frequencies stored in your memory

channels. Channels 14-16 hold frequencies in the blocked-out

66-88 Mhz range, and channel 23 holds a frequency in the

blocked-out cellular base range. Once you have these

frequencies stored in a memory channel, the PRO-51's direct

search feature will let you search though these ranges. In

the cellular band, the scanner searches in the correct 30 Khz

steps.



You don't have to keep these frequencies in the channels they

were stored by the test mode. You can move them to any

channel in the scanner. HereUs how.



First move the frequency to a monitor channel:



While on a channel with one of these frequencies, open

squelch completely. Press direct search button, either up or

down. The direct search button puts the scanner into search

mode and the open squelch holds the frequency. Then press the

Monitor button. The frequency is now in the monitor channel

indicated in the display.



Now you can move it to any regular memory channel in the

scanner:



Enter the channel number

Press PROG

Press MONI

Press the number of the monitor channel if the proper channel

is not displayed

Press E(nter)



The frequency is now permanently stored in the memory

channel. You can do a direct search from this memory channel

at any time.



The 66-88 Mhz range mainly covers TV audio. However, there is

a strange phenomenon concerning TV audio and the PRO-51.

Channels 4, 5, and 6 fall within the 66-88 Mhz range (71.75

Mhz, 81.75 Mhz, and 87.75 Mhz respectively), yet the PRO-51

will not pick up the audio frequency while searching in this

range. However, TV channel 2 audio is at 59.75 Mhz. When you

add the intermediate frequency of 21.6 Mhz, you get an image

of the TV channel 2 audio appearing at 81.35 Mhz. This does

come in, although raspy, since the PRO-51 is receiving in

narrow FM mode while TV audio requires wide-band FM mode for

proper reception.



I'd be interested if anyone can verify that any of these test

modes work on the PRO-46 or any other Uniden-made Radio Shack

scanner.



Howard Bornstein



CompuServe 76174,637

Internet:76174.637
--------------------------------------------------------------------

Piran Mohazzabi

piran




From: moy
Newsgroups: rec.radio.scanner

Subject: PRO-51 Mod:Shorten squelch tail

Date: 20 Sep 1994 20:34:06 -0500

Organization: UTexas Mail-to-News Gateway

Lines:89

Sender: nobody
Message-ID: <9409210139.AA07611
Nntp-Posting-Host: news.cs.utexas.edu



Hello fellow scanbots,



Radio Shack PRO-51:Modification to shorton squelch tail



This change was performed successfully on a unit coded "11A3."  The

CPU in this unit was marked "Uniden UC1581."  Use the following

information at your own risk!  Neither I nor my employer are

responsible for any damages you may incur from this information!



Orientations are with the set flat on a work surface, LCD display

facing down, with antenna BNC and knobs facing away from yourself.



As with any electronic instrumentation, remove all power and take

all necessary precautions to prevent damage from electrostatic

discharge (ESD).  This modification requires fine soldering and

familiarity with surface mount devices.



CAUTION:



Be aware that parts of the circuitry will *still* be powered!

There is a capacitor on the digital board that keeps the channel

memory alive.  This capacitor may contain enough energy to damage

the electronics should a short occur.



Parts required:One 1/10th watt carbon resistor, 100K to 220K.  Value is

not critical.  A lower value shortens the time the squelch remains open

after incoming signal stops.  The resistor should physically as small

as possible.



Opening Case



Fortunately, this set is very easy to open.  Open battery

compartment and remove batteries.  Remove four screws:two

straddle the sticker on the back of the cabinet, two others at the

upper part of the battery compartment.  There are two small

plastic detents at the floor of the battery compartment.  They are

directly downwards from the "-" and "+" legends, which are molded

on an extension of the removable back.  These detents will need to

be unhitched to allow the back to separate from the front.

Pull back off gently.



Remove RF board



The RF board is attached to the top panel, which contains the

volume and squelch controls and the antenna connector.  At this

point, the board is essentially free and will separate from the

rest of the set when the header connector at the lower right is

pulled apart.  This header provides electrical connections between

the two boards.  Lift the RF board straight out, and set the rest of the

radio aside.  Flip RF board over, keeping BNC pointing away from

yourself.



Add resistor



Refer to the ASCII diagram below.  Bend one of the resistor leads close

to the body of the resistor so that the resistor forms a hairpin shape.

Trim leads and solder the new resistor in parallel with the chip

resistor marked "105."  The latter is positioned between the two

surface-mount IC's towards the bottom of the RF board.  Press the new

resistor parallel to the circuit board, making sure there are no

shorts.



                   +------------+

         [101]     |            |

                   |            |

         [684]     |  NJM2090V  |

                   |            |

         [224]     |            |

                   +------------+

         [   ]   [   ]            [  || ]



         [225]   [105]              [123]

                 |   |

                 |  +-+

                 |  |R|   <---add resistor:100K - 220K

                 |  +-+

                  \_/       +------------+

                            |            |

                            |            |

                            |  TK11900M  |

                            |            |

                            |            |

                            +------------+





Thanks to Bob Parnass for clarifying the nature of the "squelch tail"

problem and for inspiring me to figure out this modification.



Moy Wong (moy