© Howard Bornstein June 2, 1994.
(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
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
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
This fills channels 1-25 with these frequencies:
* 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,
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
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
Enter the channel number Press PROG Press MONI Press the number of
the monitor channel if the proper channel is not displayed Press
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
These test modes also work on the Uniden-made PRO-46 and PRO-23 Radio Shack scanners.
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