Kenwood TKR-751 Modification Information
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7 Modification Information (MOD) Version: 1.02 USA3 INSTALLING THE VOICE SCRAMBLER BOARDIt can install an optional Voice Scrambler board into theTKR-750/850/751/851. This section describes how toinstall the TRANSCRYPT SC20-460 in it. You can use theKENWOOD service part (E37-0808-05) when installingthe SC20-460 board.! Requirement Items・ TKR-750/850/751/851・ SC20-460・ KENWOOD Part (E37-0808-05)・ Cushion TapeYou must turn the power OFF beforeinstalling the Voice Scrambler board.3.1 Configuring and Modifyingthe SC20-460 Board1. Modify the SC20-460 board and change the RX AudioInput method.TKR-750/850/751/851 output a received audio afterDe-emphasizing to input into the option board.Therefore, it might be necessary to modify the voicescrambler board.(Confirm your SC20-460 is enabled de-emphasis.)1-1. Cut the foil between E52 and E53.1-2. Solder the position between E51 and E52 toconnect them.1-3. Solder the position between E53 and E54.3. Change the constant in conjunction with the TX/RXAudio level.3-1. Replace R1 with 100 kΩ and R3 with 100 kΩ inconjunction with the RX Audio level.3-2. Replace the R2 with 6.8 kΩ and R4 with 6.8 kΩ inconjunction with the TX Audio level.Note:" The required modification must be performed to avoidproblems, such as too small audio signals from the speaker,or too loud synchronizing noise." Refer to the Voice Scrambler board's instruction manual fordetails.4. Disconnect the cable connected to the SC20-460board.5. Solder the KENWOOD service parts (E37-0808-05)cables to the SC20-460 board. You must connect thepart as shown in the as shown below. (Refer to 1.4 14-pin Connector (CN601).)Before modification After modificationR1, R3: 100 kΩ R1, R3: 100 kΩ (No modification)R2, R4: 100 kΩ R2, R4: 6.8 kΩE51E52E53E54E51E52E53E54Before AfterR4R3R2 R1 |
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