Information on the Radio Shack COMP-100 (RS first programmable scanner)

The Radio Shack 16 channel COMP-100 is similar to the BC101 in some ways but the switch settings and formulas used to enter the frequencies are different. The radio originally came with two manuals.  One was the operators guide and the other "BIG" manual contained hundreds (if not thousands) of switch settings for many frequency values.   If you lost your "BIG" manual the program below is a helpful tool.

comp100.bas  (Right click on the file name to save to disk, requires BASIC to run)

A basic program I wrote for switch settings on my COMP-100.  It sure beats doing all those multi-step formulas if you lost your "BIG" manual.

The 16 digits of code are divided into 4-digit groups.

Group 1    group 2    group 3         group 4
1 2 3 4    5 6 7 8   9 10 11 12    13 14 15 16

Determining group 1:
The first 3-digits of group 1 are decided by the frequency band you
want to receive.

VHF LO  (30-50 MHz)    000 ... X=0
VHF HI  (150-172 MHz)  001 ... X=120
UHF LO  (450-470 MHz)  010 ... X=420
UHF MID (470-490 MHz)  011 ... X=440.0025
UHF HI  (490-512 MHz)  100 ... X=460.0025

Determine the fourth digit by using the following formula.

(Desired frequency (in MHz) - X from above chart + 10.7)/12.8=4th digit
in group 1.

The answer will be over 3 and less than 5. If the integer part of the 
answer is 3, the fourth digit will be "1"; if the integer part is 4, the
fourth digit will be "0".

Now you have all of group 1.

Determining Group 2:

Using the decimal part of the answer obtained from the formula. Multiply 
it by 16. Convert the integer part into binary digits, using the binary
digit chart. Use this for group 2.

Determining Group 3:

Use the decimal part of the answer obtained under group 2 calculations.
Multiply it by 16. Convert the integer part into binary digits. Use this 
for group 3.

Determining Group 4:

Use the decimal part of the answer obtained under group 3 calculation.
Multiply it by 10. Convert the integer part into binary digits. Use this
for group 4.

Now you have all four groups, Good luck. To make sure you are doing it right,
try it with a know frequency like a local WX frequency.

Binary Digit Chart:

Integer Part     Binary Number
0                0000
1                0001
2                0010
3                0011
4                0100
5                0101
6                0110
7                0111
8                1000
9                1001
10               1010
11               1011
12               1100
13               1101
14               1110
15               1111

COMP-100 5-Band FM Scanning Monitor Receiver
(200-0110)                  Operation                 Faxback Doc. # 31131

Programming

1.  Select the channel you want to enter a program frequency by pressing
    the MANUAL button as many times as required to move the light on the
    channel indicators to that desired channel.

2.  Slide the Program Door open and press in the PROGRAM button.  If the 
    Program Indicator lights up, the unit is ready to receive a new
    program.

3.  Find the code from the Code Table to match the frequency you want.
    The numbers tell you which Digit Switches should be "out" and * marks
    show which digit switches remain "in".

4.  After you have set the code into all 16 Digit Switches, press the
    ENTER button.  The Code Indicators are lighted to reflect the new
    program code for the frequency  entered.

5.  Press the PROGRAM button again to release it (button out).  The
    program light goes out, the code indicator LEDs go out and the only
    light "on" is for the selected channel.

6.  Press all of the Digit Switches in (buttons in).

7.  To enter another program, select a channel and the frequency desired
    and repeat Steps 1 through 5.

8.  After programming,  close the program door, and you are ready to
    receive signals.

(IR-03/07/96)

Thanks and Happy Scanning !