Radio Shack PRO-51 Test Modes

© Howard Bornstein June 2, 1994.
Design EQ

(Revised 10/10/94)
(Revised 11/4/94)
(Revised 4/11/95)
(Revised 7/23/96)
(Revised 5/24/97)
(Revised 6/19/00--removed reference to Cellular Security Group)

[This document may be freely distributed for all non- commercial purposes as long as it is distributed unchanged and complete.]

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 (this test mode only works for older PRO-51 scanners. See the update notice at the bottom of this document for details).

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 diagnostic 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.

How to use the test mode frequencies

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. Here's 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.

These test modes also work on the Uniden-made PRO-46 and PRO-23 Radio Shack scanners.

Update Notice

Apparently, as a result of this document and publication elsewhere of this test mode, the FCC demanded that Radio Shack pull all existing PRO-51s, PRO-23s, and PRO-46s off their shelves and were forbidden to continue to sell them. This is particularly puzzling, since all three of these scanners could always receive cellular via images without any special modes or procedures.

At the end of October 1994, PRO-51s started reappearing in Radio Shack stores (date code of 7A4). These units were apparently shipped to Uniden to have the cellular frequency that appears in test mode 1 (channel 23) removed. If you follow the procedure for test mode 1 on the new PRO-51s, you'll instead get the frequencies from test mode 2, which will not allow you out-of-band reception.

However, Uniden apparently didn't spend much time with this interim modification because it is still possible to put the "new" PRO-51s into test mode 1. Here is the procedure:

First initialize test mode 3 (the display test). While the display is being updated, hold down the 2, 9, and L/Out keys. Keep holding them until the display finishes filling up. It will stop with all of the test frequencies for test mode 1 loaded in memory!

Unfortunately, PRO-51s with a date code of 8A4 (August 1994) or later will be able to do all the test sequencies with the exception that channel 23 will not contain a frequency in the cellular range. The other out-of-band frequencies will still be there.

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