This article/file is for the benefit of all.



(c) 1995-96 <All Rights Reserved> Bill Cheek-COMMtronics Engineering



This article/file is for personal use only and may NOT be placed 

on a CD-ROM nor any other media that conveys, stores, or transports 

for any monetary cost, without expressed permission of the author.

This file can only be given away, absolutely free of charge.



                                   -Bill Cheek-





NFM DISCRIMINATOR CHIPS - BASEBAND AUDIO - SQUELCH GATE DATA

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



There is a growing interest in tapping the baseband audio 

out of various scanners for decoding of a variety of esoteric 

signals, including CTCSS, SCA, FSK, RTTY, FAX, etc.  By and

large, such signals cannot be take from TAPE REC jacks, 

headphone jacks, and EXT SPEAKER jacks because of the voice-band 

filtering that is done between the signal source and these 

output jacks.



Therefore, it is necessary to tap the "baseband audio" directly 

at the output of the discriminator chip for your scanner.  The 

below Table shows a list of scanners, the discriminator chip(s) 

used in the scanner, circuit symbols of those chips, and three 

pins of general interest on the chips: RF-Input, Scan Control, 

and, of course, the baseband audio pin.



Even though your scanner may not be listed below, try to find 

its discriminator chip, and chances are it will be listed with 

one or more scanners below, the pins of which will be the same 

for your unlisted scanner! Corrections and  additions to this 

list are requested.  See my mail and other addresses at the end 

of this file.



          SCANNER DISCRIMINATOR CHIP PINS OF INTEREST

Updated  1/6/97

                                CKT     RF-in   SCAN    AUDIO

SCANNER         NFM CHIP TYPE   SYMBOL  Pin     Pin   BASEBAND

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

                MPS5071         n/a     16      13      9

AR-1000         TA-7787AF       IC-4    16     none     9

AR-2002         MC-3357P        IC-4    16      13      9

AR-2500		TA-7761P	IC-13	16		9

AR-3000         MC-3357P        ?       16      13      9

AR-800          MC-3361N        IC-200  16      13      9

AR-900          MC-3361N        IC-201  16      13      9

AR-950          MC-3361N        IC-201  16      13      9

AR-8000 NFM     TK10489M or-85M U1      20     16-17    11

AR-8000 WFM/AM  TA7792F         U3      16       -      8

BC-100XL        MC-3359P        IC-1    18      15      10

BC-100XLT       TK-10421M-2     IC-401  20      16      11

BC-140XLT       MC-3359P        IC-1    18      15      10       *

BC-200XLT       TK-10421M-2     IC-401  20      16      11

BC-205XLT       TK-10421M-2     IC-401  20      16      11

BC-250          ?               IC-3    16      13      9

BC-2500XLT      TK-10930VTL     IC-201  24      -    12-FM  13-AM

BC-3000 NFM/AM  TK-10930V       IC-202  24      -    12-NFM 13-AM

BC-3000 WFM     TK-10489M       IC-203  20     16-17    11

BC-350A         NJM-3359D-A     IC-3    18      15      10

BC-400XLT       NJM-3359D-A     IC-1    18      15      10

BC-560XLT       NJM-3359D-A     IC-1    18      15      10

BC-700A         NJM-3359D-A     IC-3    18      15      10

BC-760XLT       NJM-3359D-A     IC-2    18      15      10

BC-800XLT       MC-3359P        IC-1    18      15      10

BC-8500XLT      MC-3361BP       IC-9    16      13      9

BC-855XLT       TK-10421M-2     IC-401  20      16      11

BC-890XLT       NJM-3359D-A     IC-3    18      15      10

BC-950XLT       NJM-3359D-A     IC-2    18      15      10

HX-1000         TK-10420        U-201   16      13      9

MR-8100         NJM-3359D-A     IC-3    18      15      10

MX-5000         MC-3357P        IC-4    16      13      9

MX-7000         MC-3357P        IC-4    16      13      9

PRO-2002        MC-3357P        IC-101  16      13      9

PRO-2003        MC-3357P        IC-104  16      13      9

PRO-2004 NFM/AM TK-10420        IC-2    16      13      9 (TP4)

PRO-2004 WFM    KB4419A         IC-1    1       -       6 (TP3)

PRO-2005 NFM/AM TK-10420        IC-2    16      13      9 (TP2)

PRO-2005 WFM    KA2243N/HA12413 IC-1    1       -      10 (TP1)

PRO-2006 NFM/AM TK-10420        IC-2    16      13      9 (TP2)

PRO-2006 WFM    KA2243N/HA12413 IC-1    1       -      10 (TP1)

PRO-2011        TK-10420        IC-1    16      13      9

PRO-2020        MC-3357P        IC-101  16      13      9

PRO-2021        TK-10420        IC-2    16      13      9

PRO-2022        MC-3361N        IC-1    16      13      9

PRO-2023        NJM-3359D-A       ?     18      15      10

PRO-2024        MC-3361N        IC-2    16      13      9

PRO-2025        NJM-3359D-A     IC-1    18      15      10

PRO-2026        NJM-3359D-A     IC-7    18      15      10

PRO-2027        MC-3361N        IC-2    16      13      9

PRO-2028        NJM-3359D-A     IC-2    18      15      10

PRO-2030        NJM-3359D-A     IC-3    18      15      10

PRO-2035 NFM/AM TK-10420        IC-2    16      13      9 (TP2)

PRO-2035 WFM    KA2243N/HA12413 IC-1    1       -      10 (TP1)

PRO-2042 NFM/AM TK-10420        IC-2    16      13      9 (TP2)

PRO-2042 WFM    KA2243N/HA12413 IC-1    1       -      10 (TP1)

PRO-23          MC-3361BD       IC-1    16      13      9

PRO-26 NFM/AM   TK-10930V       IC-14   24      -    12-NFM 13-AM

PRO-26 WFM      TK-10489M       IC-16   20     16-17    11

PRO-31          TK-10420        IC-1    16      13      9

PRO-32          TK-10420        IC-101  16      13      9

PRO-34          TK-10420        IC-101  16      13      9

PRO-35          TK-10421M-2     IC-401  20      16      11

PRO-36          TK-10420        IC-101  16      13      9

PRO-37          TK-10420        IC-101  16      13      9 (TP103)

PRO-38          MC-3359P        IC-1    18      15      10

PRO-39          MC-3361N        IC-201  16      13      9

PRO-41          MC-3359P        IC-1    18      15      10

PRO-42          MC-3361N        IC-2    16      13      9

PRO-43          TK-10427/-10420 IC-301  16      13      9

PRO-44          MC-3361N        IC-201  16      13      9

PRO-46          TK-10421M-3LT   IC-401  20      16      11

PRO-51          MC-3361BD       IC-1    16      13      9

PRO-60          ?               IC-301  16      13      9

Icom R-1 NFM	TK-10487  DET-A IC-1	20      Q1      11

Icom R-1 WFM	TA-7787AF DET-B IC-1	16       7      9   

Icom R7100	Said to be "top of R230 on the top of main PCB"   *

R-1600          NJM-3359D-A     IC-2    18      15      10

R-4030          TK-10421M-2     IC-401  20      16      11

SR-15           TK-10421D-2     IC-1    16      13      9

StandardCCR708A TK-10420D	Q602    16      13      9         *

TurboScan 2     3130-6056-502   U-201   18      ?     10 or 16

Yaesu FRG-9600  MC-3357P           ?    16      13      9         *

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

* Not personally verified by me



    UNIDEN SCANNERS and Realistics made by Uniden

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



    Uniden does their darndest to make it difficult to

    hack their scanners. You guys have some work to

    do.  Here's the deal: Even though all NFM

    discriminator chips have a SCAN CONTROL pin,

    Uniden doesn't always use it!  Some Uniden

    scanners have a separate Squelch circuit with the

    SCAN CONTROL pin on the discriminator unused!  You

    have to find the real Squelch circuit, and then

    determine the Logic for that circuit.  It's easy,

    but differs from one scanner to the next, and I

    can't cover them all.  I need your help.



    See Table 2 below for a good reference. By and

    large, those with scanners of Uniden origin have

    to tackle the preliminaries in this fashion:



    1.  Locate the NFM Discriminator chip - you will

    find the Audio pin from Table 1. It remains valid.



    2.  Determine if the SCAN CONTROL pin on that chip

    is used. (Follow its trace out on the PCB)



        A.  If so, then determine the logic order. If

            the SCAN CONTROL pin is used, then we can

            use it!



        B.  If the SCAN CONTROL pin is not used,

            then locate the real Squelch circuit.

            The schematic and block diagrams in

            the service manual will be helpful.

            Uniden uses chips like NJM2902,

            NJM2904 & NJM3403 to generate Squelch

            logic.  Use your voltmeter to find a

            spot where the Squelch logic is 0v and

            5 or 8v, depending on the setting of

            the Squelch control. Table 2 shows

            details for those Uniden-made scanners

            with which I am familiar.



                   TABLE 2

             UNIDEN SQUELCH CHIPS

              Updated  4/08/96



Scanner     SQ Chip    CktSym  Pin

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

PRO-26      NJM3403AV  IC-17    14

BC-890XLT   NJM2902N   IC-8      7

BC-2500XLT  NJM3403AV  IC-204   14

BC-8500XLT  NJM2904M   IC-8      7

BC-350A     NJM2904S   IC-552    8

BC-700A     NJM2904D   IC-11     7

PRO-51      NJM2902V   IC-4      8

PRO-2030    NJM2904S   IC-10     8



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



   This file is copyrighted (c) 1995-97 <All Rights Reserved>



Please let me have your input and feedback on the above information 

and Table, especially for additions and corrections.



Thanks,



+----------------------------------------------------------------------+

| Bill Cheek                E-mail: bcheek@cts.com  FidoNet: 1:202/731 |

| COMMtronics Engineering   Compuserve:  74107,1176                    |

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+----------------------------------------------------------------------+



