Blocked out ranges:
54-136,
174-406,
512-806,
824-851,
869-896 * ( see below )

This operations will overrride your saved channels ! be carefull.
A) *To get to 869-896 mHz do the following: turn your scanner OFF, hold down 9, 2 and L/O while turning it ON.
Channel 23 should now have a frequency that is inside of this range.Other channels should have a bunch of other test frequencies.
You can scan UP or DOWN in 30 kHz ( whoa ) steps between 869 - 896. Just go to MANUAL mode, switch to channel 23 and hit UP or DOWN arrow.

B) To set all channels to zero ( if you ever need this ) hold down 9 and 2 while turning the scanner ON.

Accessing blocked out ranges.
Tested on PRO-51 with the manufacture code 12A3 (Dec 93). If works on others - let me know.

DISCONNECT YOUR ANTENNA.TURN THE DELAY OFF.
TURN THE SQUELCH ALL THE WAY CLOCKWISE.
SCANNER SHOULD BE RECEIVING NO SIGNALS WHATSOEVER.

1.Choose a frequency range to experiment with , for example 174mHz - 406mHz which is "blocked" on PRO-51.

2. Enter a "LIMIT" scanning mode by hitting PROG, then LIMIT then the arrow DOWN.
Display shoud show LO and some number.

3. For the LOWER LIMIT enter a frequency 1mHz below the blocked out 174mHz. and press ENTER.

4. Program the UPPER LIMIT by pressing UP arrow ( displays HI and some number) then entering a frequency 1mHz above 406 mHZ. Press ENTER.

5. Now if you press DOWN arrow your scanner should continuously loop from 407 to 173 ( in this case ) skipping everything in the blocked out region. In other words it will go down from 407 to 406 and then immediately to 174, then to 173 and then starts from 407 again.

6. Switch to SCAN while digits are between 407 and 406 mHz. If you missed it first time , wait - it will repeat again.
( If you entered SCAN too late - go back to LIMIT and hit DOWN arrow and wait for your moment of zen again.)

7.Now from SCAN switch back to LIMIT and hit DOWN arrow.

8 Watch the numbers go down to 406 mHz .... and then past it to 404 .. 403 .. 300 and so. If the scanner gets stuck on some frequency ( strong signals may interfere with this "magic" process) just swirl your scanner up-down-around so it loses the signal ( DELAY must be OFF !!!!!).

9. You can now save any of those frequencies by hitting MONITOR. then MANUAL, then channel number to store it in, then PROG then MONITOR ( the "kidnapped" frequency will show up on display ) then ENTER. Now the frequency is stored in the selected channel. Just save some frequencies in the channels any way you want them ( every 20 mHz or so )

You may go back to LIMIT and continue ( arrow down ).

To use: in the MANUAL mode go to the channel you programmed the frequency in to and hit arrow UP to scan UP in the blocked out range. Arrow DOWN will not work and throw you out of the blocked range. If no signal present - check if you plugged back your antenna and turned the squelch down.

Waiting for the digits to dribble from 406 to 174.0125 is a pain ( in some ranges it goes really slow).

Coming up: Discriminator output with pictures, squelch shortening instructions, annoying keyboard beep removal. Wider IF fiter addition.