This article/file is for the benefit of all. (c) 1995-96 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 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 | | World Scanner Report Voice Phone: (619) 578-9247 1:30pm-5:30pm | | PO Box 262478 BBS & FAX: after 5:30pm & before 1:30pm | | San Diego, CA 92196-2478 24-hrs, weekends/holidays | | WWW home page: http://ourworld.compuserve.com/homepages/bcheek | | FTP Sites: ftp://ftp.cts.com/pub/bcheek | | ftp://ftp.cts.com/users/crash/b/bcheek | +----------------------------------------------------------------------+