Note from the author:  I'm sorry I didn't publish this information sooner.
I've known of the extended capabilities of this radio for a couple of years.
I made a few attempts to make deals with various radio mod shops.  Most felt
the time needed to make key pad entries was too long to make a profit.  I hope
you'll enjoy the added coverage of the radio, and forgive my belated release
of this information.

If you have questions, I will try to answer them via e-mail.

Please, feel free to share this information with others that own one of these
fine radios.  I would appriciate it if you included my call sign with all
copies of this information.

-Al n8kli@aol.com

PRO-43 Shortwave & Extended Receive
Al Mellon N8KLI

(This modification is only possible on radios able to be modified to receive
the full 800 MHz range.)

Scope and nature of the modification:  To allow the PRO-43 to receive
frequencies from 6 MHz to 1000 MHz.  This is accomplished by setting the PRO-
43 to non-standard splinter frequencies, the CPU will then step the radio
beyond the normal band edges.  To derive the non-standard splinter frequencies
it is necessary to change the diode configuration matrix, and to use the
monitor-search function.  The hardware modification should take about thirty
minutes.  The remaining programming / search will take as little as 45 minutes
(depending on how interested you are in the signals you encounter during the
806 MHz to 30 MHz search to be run).

I claim no responsibility for any damage done to your radio by attempting this
modification.  I will also not be responsible if you use this radio to break
the law by monitoring cellular mobile telephone transmissions.

Anyone attempting this modification should be comfortable working with surface
mounted components and have a reasonable familiarity to the key pad functions
of the radio.

STEP 1  (DRAWING 1)

- Remove the antenna

- Remove the battery pack

- Remove the four screws (A)

- Remove the rear cover






STEP 2  (DRAWING 2)

- Remove the six screws (A)

- Using a knife blade, pry the connector at the bottom of the circuit board
  apart (B)

- With the connector (B) apart the top circuit board can be pressed side to
  side to allow removal of the two hidden screws (C)

- Lift the two stacked circuit boards (watch the connectors on the right edge
  of the main board)

- Swing the two stacked boards to the left (as shown by the arrows)



STEP 3  (DRAWING 3)

- Remove the RF shield by heating the four solder pads (A) and GENTLY prying
  the shield up at the corners.  Watch for any surface mount components!

STEP 4

- Note the location of diodes D1 - D5 (factory U.S.  configurations has diodes
  D1, D2, D4 in place).
  See DRAWING 4

  Diodes D1 - D5 enable the following functions
     D1 - KEY LOCK switch enable
     D2 - 30 MHz to 54 MHz enable
     D3 - 54 MHz to 88 MHz enable
     D4 - Cellular lockout enable
     D5 - Cellular 12.5 KHz step enable

  The normal broad band coverage modification (DRAWING 5A) has D1, D2, D3 in
  place providing the following coverage:
      30 MHz to 88 MHz
     118 MHz to 174 MHz
     220 MHZ to 512 MHz
     806 MHz to 999.9875 MHz
     (30 KHz cellular channel spacing)

  If your radio does not have D3 then move D4 to position D3

  D5 should not be in place

  See DRAWING 5B.  Solder a diode - cathode side (has the line) to the upper
  side of the D5 position.  Make sure that the leads are the proper length to
  allow this new diode to sit on top of D2 and D3, and that none of the legs
  touch.  Solder the anode side to the lower side of the D1 position.

  Installation of this diode allows the user to select the channel spacing in
  the cellular bands.  KEY LOCK off at time of power on yields 30 KHz spacing.
  KEY LOCK on at the time of power on yields 12.5 KHz spacing.  By using the
  monitor memory and changing this configuration in the middle of a search in
  the cellular band we are able to derive non-standard splinter frequencies.
  This seems to evade the CPU programming of the allowable band edges,
  allowing the radio to search beyond normal frequency coverages.  At 30.005
  MHz, the next downward frequency (at 5 KHz steps) is 30.000 MHz.  The CPU
  then realizes it has reached the lowest valid frequency, so that the next
  step down the operating frequency is set to 999.9875 MHz.  We will store a
  frequency of 30.0025 MHz in channel 200.  Using the DIRECT feature of the
  radio we are able to tune to a frequency above or below any stored
  frequency.  The CPU reads 30.0025 steps down by 5 KHz and is now at 29.9975.
  Since the frequency still does not equal 30.000 MHz it is able to step down
  again.  29.9925 MHz - you probably get the idea.  At 2.5 KHz it does jump up
  to 999.9975 MHz and then to 895.9875 MHz.  (Sensitivity drops below 15 MHz,
  but remains useable to about 6 MHz.) In the procedure below you will store
  band edge frequencies that can be stepped above or below to grant added
  coverage.  The CPU will not store in memory any frequency outside of the
  permitted coverage.  This necessitates the use of the direct mode.

STEP 5

- Reassemble the radio

STEP 6  Keyboard entries

- With the KEY LOCK switch OFF turn the radio on.  The unit will now step by
  30 KHz steps from 825 MHz to 845 (cellular mobile input channels - base
  channels are 870 MHz to 890 MHz)

- Set the squelch to open (MIN) and volume to low

- Enter to the key pad

     PGM   LIMIT   30   ENTER   LIMIT   825.120   ENTER

     DOWN   LIMIT   DOWN   MON

     (The display should read  825.120 down search)

- Turn the KEY LOCK switch ON and turn the radio off

- Turn the radio on and set the KEY LOCK switch to OFF

- Enter to the key pad  (Squelch should still be open.)

     MANUAL   MON   DIRECT   DOWN

     (The display should read  825.1075 down search)

- Close the squelch to allow the radio to search down.

- Use the  UP  DOWN  and the squelch control to stop the radio at 806.0075 MHz

- Enter to the key pad

     MON   PGM  194  PGM  MON  ENTER

     (Channel 194 has now been programed with 806.0075 MHz)

     DIRECT   DOWN

     (The display should read  805.9950 down search)

- Close the squelch to allow the radio to search down.
  (I've noticed birdies in the 560 to 700 MHz range.)

- Use the  UP  DOWN  and the squelch control to stop the radio at 511.995 MHz

- Enter to the key pad

     MON   PGM  195  PGM  MON  ENTER

     (Channel 195 has now been programed with 511.995 MHz)

     DIRECT   DOWN

     (The display should read  511.9825 down search)

- Close the squelch to allow the radio to search down.

NOTE:  From this point on, I have listed frequencies that you most likely will
program to your radio.  If your frequencies are not exactly the same, they
will work as long as the last small digit is a 5 (.5 Khz), and the frequency
is within the normal allowable frequency band limits.  By this time you have
probably noticed that the search step is per the next valid band the radio
will encounter in the direction being searched.

- Use the  UP  DOWN  and the squelch control to stop the radio at 220.0025 MHz

- Enter to the key pad

     MON   PGM  196  PGM  MON  ENTER

     (Channel 196 has now been programed with 220.0025 MHz)

     DIRECT   DOWN

     (The display should read  219.9975 down search)

- Close the squelch to allow the radio to search down.

- Use the  UP  DOWN  and the squelch control to stop the radio at 173.9975 MHz

- Enter to the key pad

     MON   PGM  197  PGM  MON  ENTER

     (Channel 197 has now been programed with 173.9975 MHz)

     DIRECT   DOWN

     (The display should read  173.9925 down search)

- Close the squelch to allow the radio to search down.

- Use the  UP  DOWN  and the squelch control to stop the radio at 118.0225 MHz

- Enter to the key pad

     MON   PGM  198  PGM  MON  ENTER

     (Channel 198 has now been programed with 118.0225 MHz)

     DIRECT   DOWN

     (The display should read  117.9975 down search)

- Close the squelch to allow the radio to search down.

- Use the  UP  DOWN  and the squelch control to stop the radio at 87.9975 MHz

- Enter to the key pad

     MON   PGM  199  PGM  MON  ENTER

     (Channel 199 has now been programed with 87.9975 MHz)

     DIRECT   DOWN

     (The display should read  87.9925 down search)

- Close the squelch to allow the radio to search down.

- Use the  UP  DOWN  and the squelch control to stop the radio at 30.0025 MHz

- Enter to the key pad

     MON   PGM  200  PGM  MON  ENTER  AM/FM

    (Channel 200 has now been programed with 30.0025 MHz AM)


To listen to Rush at noon on WRNO  15.420 MHz

- Enter to the key pad

     MANUAL  200  MANUAL  DIRECT  DOWN

- Use the  UP  DOWN  and the squelch control to stop the radio at 15.4155 MHz

- Enter to the key pad

     UP   (The display will now read 15.4175)
     MON  The radio is now locked to the correct frequency (the AFC will lock
          the radio to 15.420 MHz)

To listen to CB-19 27.185 MHz

- Enter to the key pad

     MANUAL  200  MANUAL  DIRECT  DOWN

- Use the  UP  DOWN  and the squelch control to stop the
  radio at 27.1775 MHz

- Enter to the key pad

     UP   (The display will now read 27.1825)
     MON  The radio is now locked to the correct frequency
          (the AFC will lock the radio to 27.185 MHz)

To listen to TV channel 8 audio on 185.760 MHz

- Enter to the key pad

     MANUAL  197  MANUAL  DIRECT  UP

- Use the  UP  DOWN  and the squelch control to stop the
  radio at 185.7575 MHz

- Enter to the key pad

     MON  The radio is now locked to the correct frequency
          (the AFC will lock the radio to 185.760 MHz)

To listen to Civil Air Patrol on 26.620 MHz

- Enter to the key pad

     MANUAL  200  MANUAL  DIRECT  DOWN
- Use the  UP  DOWN  and the squelch control to stop the
  radio at 26.6125 MHz

- Enter to the key pad

     UP   (The display will now read 26.6175)
     MON  The radio is now locked to the correct frequency
          (the AFC will lock the radio to 26.620 MHz)

STEP 7

- Ask yourself why Radio Shack did not include shortwave or extended VHF
  coverage in the PRO-43 software.

  Answer:  They wanted to sell you a shortwave receiver too.
                                    - OR -
           They've just grown accustomed to following the leaders, not being
           one.

Notes:

*****> It is necessary to drop below the desired HF band frequency and then
search up to re-enable the VHF-LO band circuitry.  None of the other bands
require this. <*****

The lowest frequency I've been able to copy with out modification of the RF
cicuitry is 5.8 MHz.

The best SWL sensitivity is from 15 MHz and up.  I use my 2 meter 5/8 wave HT
antenna for SWL and have good results from my office.  As with all rigs, an
outdoor antenna works far better than an undersized rubber duck.

When listening to 10 meter FM check your mode.

If the key pad operations must be interupted, it is not neccesary to restart
the programing from 825.120 MHz.  Simply go to the last memory channel
programed with a non-standard splinter channel in the manual channel mode.
Then enter to the key pad

     DIRECT   DOWN

This will restart the search from the last possible frequency.


Steps to enhance the HF receive sensitivity.

     - Remove L101

     - Add the following circuit

                           Cx1    Lx1
              Point 1 o)|@@@@@@@o Point 2

                         )|             )|
                           Cx2               Cx3   GND


          Cx1 = .01uF Cap
          Cx2 = .01uF Cap
          Lx1 = inductor (use L101 if not broken)  I used an inductor from a
                Radio Shack Bulk part assortment 273-1601
          Cx3 = .047 pF Cap (Approximately)
          Point 1 = Juntion L101 & C101 & Ant connection
          Point 2 = Juntion L117 & C205 & R135