From : G1YYH @ G1YYH.GB7CRG.NW.GBR.EU To : MODS @ GBR Date : 891214/2036 Msgid : BF 204@G1YYH, 14571@GB7YHF $THX5AT.PT1 Subject : Kenwood TH-x5at Mods - 1/4 Path : GB7YAX!GB7CHS!GB7CRG!G1YYH Date: 3 Dec 89 20:27:01 GMT From: tank!cps3xx!usenet@handies.ucar.edu (Usenet file owner) Subject: modifications for Kenwood th-X5at handhelds Message-ID: <5652@cps3xx.UUCP> In the past, I posted some mods for the Kenwood TH-X5AT series of HTs. My previous posting had some minor errors, and left some questions unanswered. Yesterday, I helped a friend modify his TH-45AT, and some of these questions were answered. This posting will clear up the problems in the previous posting, as well as contain all of the important information from the previous posting. You may delete your previous copy of this information, and replace it with this one. --------------------------------------------------------------------- Copyright (C) Notice: Some people have been taking information posted to this network, publishing it, and selling it. Not only is this immoral, it is also illegal. You may not do this. I give everybody the right to copy this material, and give it to others. You must not sell it. You may NOT include this information in a newsletter or compendium that you charge for, but you may incude it in a free newsletter or compendium. You may NOT distribute this information on a computer bulletin board system that users are charged any fees for, but you may distribute this information on a computer bulletin board system if you provide the service free of charge. You must not alter the information provided here in any way, including removing this copyright notice and/or removing the authors' name and/or e-mail address at the end of this message. --------------------------------------------------------------------- Here are some mods for the TH-25AT and the TH-45AT. Please note that I do not encourage transmitting on a frequency for which you do not have a license, nor do I encourage transmitting in the United States on a non-amateur frequency with equipment that has not been FCC type accepted. This is illegal in the United States, even if you have a license to transmit on the given non-amateur frequency. First let me recommend that you buy the service manuals for these radios. The service manual is not expensive (about $15 I think) and it will greatly help you in performing these mods. Before performing any of these modifications, make sure you know what's in your memories, because they will be lost. --------------------------------------------------------------------- Look at the schematic for your radio. In the lower left hand corner is an IC labled IC2. This is an ASIC microprocessor. At the lower right hand corner of this uP are several diodes and pull-up or pull-down resistors. They are D4, D3, R19, R18, R28, R20, R21, R22, R25, R26, and a couple of resistors that are not even on the schematic that attach to B2 (pin 51 on IC2) and B3 (pin 50 on IC2). The TH-45AT schematic shows R23 on the ASIC uP pin B2. Another important resistor is R27; on the schematic it is located next to the frequency selection switch EN1 above IC2. A less important resistor (for modification purposes) is R36; on the schematic it is located to the right of IC2 in line with the top edge of IC2. The schematic for the TH-25AT shows: R18-R21 R25 R26,27 R28 R36 TH-25A M,M2 -12 O X X X X TH-25A M3,M4,X -23 O X X O X TH-25AT K -11 O O X X X TH-25AT M,M2 -12 O X X X X TH-25E T -52 X X O O O TH-25E W -62 X O O O O And the schematic for the TH-45AT shows: R19-R21 R22 R23 R25 R26,27 R28 R36 TH-45A M1,M2,X -21 O O O X X O X TH-45A M3,M4 -22 O X O X X X X TH-45AT K -10 O X O X X O X TH-45AT M1,M2 -21 O O O X X O X TH-45AT M3,M4 -22 O X O X X X X TH-45E T -51 X O X X O X O TH-45E W -61 X O X O O O O where O means USED, and X means NOT USED. Some of the above codes are: K USA T England X Australia M Other Areas These components are found on the flexible circuit board under the display. To get to them, take the radio apart. ---------------------------------------------------------------------