This file is meant to replace the old PRO-43 mod file.  17.12.92



Subject: cellular (870-890 MHz) and low band (51-88 MHz) restoration for PRO-43







From: armille
Summary:cellular (870-890 MHz) and low band (51-88 MHz) restoration for PRO-43



A few people have mentioned the cellular mod for the PRO-43; it turns out

you should not remove but MOVE the diode.  Doing so allows cellular coverage as

well as low band (up to 88 MHz) coverage.



Acknowledgments to Grove Enterprises; this information came from them.

They are selling the PRO-43 for $300 which is $50 less than Radio Shack.

I have no connection with them other than as a satisfied customer.



  PRO-43

Cellular Frequency Restoration and Low Band Expansion



Note:It is not lawful to monitor cellular or conventional mobile telephone

conversations.



The following procedure requires familiarity with microcircuit soldering and

will violate your warranty.  Grove Enterprises assumes no liability resulting

from its attempt, nor will accept the modified scanner for return under any

condition.



TOOLS NEEDED:Fine point, low power soldering pencil; solder wick or a

desoldering tool; pointed awl, hemostats or pointed tweezers; small Philips

screwdriver; solder.



1) Remove the battery, antenna and back cover (held in place by four screws).



2) Remove the six screws holding the top circuit board in place.  Carefully

unsolder the two antenna connections from the board.  Bend the antenna ground

tab fully up from the board.  Carefully lift the board, unplugging the black

connector at its base, and lay the board out of the way on its bundle of

colored wires.



3) Remove the two screws from the next board and lift it, carefully unplugging

the white connector at the bottom of the board.  Lift it up and lay it aside on

its brown wire (which can be unplugged if necessary).



4) Unsolder and remove the metal shield from the final board, revealing the

microprocessor; note the row of diodes labeled D1-D5 above it.  Only diodes

D1, D2, and D4 are present; assisted by a pointed tool, unsolder and remove D4,

the lone diode (this restores cellular frequencies which will be searched in 30

kHz steps).



5) Resolder the removed diode carefully into position D3 to extend low band

coverage to 88 MHz.



6) Reassemble the boards, paying particular attention to the alignment of the

plugs.  Test the radio by entering any frequency between 870 and 890 MHz

(cellular) and 51-88 MHz (low band).

--



A. Ray Miller

arm


=================



From: ross
Date: 19 Aug 92 16:51:08 GMT



Here is my keypad beep delete mod for the RPO-43:



1. Remove battery.

2. Remove back cover (4 screws).

3. Remove top board (6 screws, desolder two antenna connections and bend

   antenna ground lead up out of the way). Be careful of black connector at

   bottom of board. Flip board over and lay aside (wire connectors need not be

   disconnected).

4. Remove middle board (remove 2 screws and wire connector). Be careful of two

   multi-pin connectors along underside of board. Set middle board aside.

5. Locate 10 pin connector on side of bottom board (labeled CN3). Note that one

   end of connector has pin 10 labeled as such. Count back to pin 6 and bend

   pin 6 ninety degrees towards the large RF shield. Make sure the bent pin

   clears the RF shield.

6. Reassemble and your done OR do the cell mod since you are so close.



Have fun. Gary Ross               >usual disclaimer>



-------



Subject: Improved audio for the PRO-43 portable scanner

From: parnass
Date: Wed, 2 Dec 1992 01:15:35 GMT



      IMPROVED AUDIO FOR THE PRO-43 SCANNER



       by Bob Parnass, AJ9S



     The Radio Shack PRO-43 scanner audio is too bassy.1 The

     lack of treble makes it difficult to hear the PRO-43 in

     noisy situations, especially whilelistening in  a car

     or truck.  LouisShirleysent mea schematic andsug-

     gested I remove C341, a tiny 0.015 ufd  surface  mount

     capacitor.



     I'm glad to reportthat  removingC341  made  a  great

     improvement.   The audiois  nowmuch "crisper,"more

     like the Uniden 200xlt, although  still  not  quite  as

     loud.   Turning  the  volume control up still overloads

     the PRO-43's small, internal speaker, but there'sless

     need to dothat once C341 is removed.



     The PRO-43contains 3 printed circuit boards,  and the

     middle  (second)  board  containsthe audio circuitry.

     Finding C341 is difficult,as it is neither markedwith

     avalue nor a component designation.  It is located on

     the foil side of the  middle  board,  under  IC304,  an

     LM386 amplifier IC.  C341 is in parallel with, andphy-

     sically next to, R350 (33,000 ohm).  R350is  slightly

     larger than C341 and is marked 333.  Both R350 andC341

     are connected between pin 2 of theLM386 and ground.



 A Note About 50-88 MHz Reception



     Now that Ihave a schematic, I see that  the  European

     version  of  the PRO-43 has different coils and capaci-

     tors in the low (mid)  band  front end  filter.That

     explains why the 75 MHz sensitivity isn't stellar after

     adding diode D3 toenable 30-88 MHz coverage.



__________



 1. See"PRO-43ProductReview," by BobParnass, AJ9S, in

    theNovember 1992 RCMA Journal.



--

==============================================================================

Bob Parnass, AJ9S  -  AT&T Bell Labs  -  parnass




=============



Compiled for garfield.catt.ncsu.edu by:



Brad Steinman

University of Toledo Computer Services

cscon0151

SOURCE: The QRZ Windows Ham Radio CDROM