MFJ -1272B TNC User Manual

Tnc/microphone switch

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MFJ-1272B TNC/Microphone Switch
Introduction
Thank you for purchasing the MFJ-1272B TNC/MIC Switch. This switch is
designed to allow simultaneous connection of both your microphone and
your TNC to the radio.
The MFJ-1272B microphone switches were designed to be used with any
radio that has a standard, round, 8-pin microphone connector. Because
many TNCs have different connectors, MFJ offers 5 models:
MFJ Model Number
MFJ-1272B
12/96/900
MFJ-1272BX
MFJ-1272BYV
MFJ-1272BYH
MFJ-1272BZ
For circuit board revisions, refer to page 11.
CAUTION
Always check your radio's owner's manual to see if there is a voltage on one
of the pins of the microphone before hooking up the microphone switch.
You could damage your radio by connecting the PTT line to a voltage source.
Do not connect any pin labeled as a voltage source to PTT !
WARNING: MFJ Enterprises, Inc. is not responsible for damaged radios or
associated equipment. It is your responsibility to make sure
your connections will not damage the radio.
TNC and Multimodes
All MFJ TNCs, TAPR TNC II clones, and PK-
PK-232
KAM® VHF port, KPC-2, KPC-3
KAM HF port
PK-88
KAM is a registered trademark of Kantronics Company, Inc.

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Summary of Contents for MFJ MFJ-1272B TNC

  • Page 1 MFJ-1272B TNC/Microphone Switch Introduction Thank you for purchasing the MFJ-1272B TNC/MIC Switch. This switch is designed to allow simultaneous connection of both your microphone and your TNC to the radio. The MFJ-1272B microphone switches were designed to be used with any radio that has a standard, round, 8-pin microphone connector.
  • Page 2: Installation

    Instruction Manual MFJ-1272B Installation Before you install the MFJ-1272B TNC/MIC switch, you must set it up for your particular radio. The MFJ-1272B comes pre-wired from the factory for without Kenwood and Alinco radios RECEIVE AUDIO on the microphone jack. If you have one of these radios, the TNC/MIC switch is ready to use. If you...
  • Page 3: External Audio

    Jumper Configuration Because there are so many different radio configurations, we have tried to make the MFJ-1272B as versatile as possible. With the MFJ-1272B you can virtually connect any radio pin to just about any TNC pin, just by configuring the jumpers properly.
  • Page 4: Audio Out Connection

    Instruction Manual MFJ-1272B do not does not have RECEIVE AUDIO on one of the microphone pins, then place a jumper in the RECEIVE section of header HD1. Radio MIC Pin MFJ-1272B Place a jumper on: Header RECEIVE--R1A RECEIVE--R2A RECIEVE--R3A RECEIVE--R4A...
  • Page 5: Ground Connections

    Instruction Manual MFJ-1272B TNC comes into the radio. For example, if MICROPHONE AUDIO is designated pin 1 on a Kenwood microphone, then you would place a jumper on position R1C in the AUDIO OUT section of header HD1. Radio MIC Pin...
  • Page 6 Through Connections Table 5 shows where you would place a jumper, depending on the microphone pin functions that are not to be switched by the MFJ-1272B. Microphone pins designated, +V, UP and DOWN, are radio functions that are not needed by the TNC, but are needed for normal microphone operations.
  • Page 7 Instruction Manual MFJ-1272B Jumper positions for specific radios: KENW OOD 8 PIN MIC KENW OOD TS-6 8 0 ALINCO 8 PIN MIC ICOM 8 PIN MIC...
  • Page 8 Instruction Manual MFJ-1272B Jumper positions for specific radios: AZDEN PCS-70 00 H STANDARD C56 0 8DA RANGER AR-3 5 00...
  • Page 9 4 and 5. Connect a cable from the headphones or speaker out jack of the radio to the AUDIO IN jack of the MFJ-1272B. The AUDIO IN jack on the TNC/MIC switch requires an RCA male phono plug.
  • Page 10: Technical Assistance

    You can also send questions by mail to MFJ Enterprises, INC., 300 Industrial Park Road, Starkville, MS 39759; by FAX to 662-323-6551; or by email to techinfo@mfjenterprises.com.
  • Page 11 Instruction Manual MFJ-1272B Circuit Board Revisions Note: This manual is written for the Revision 9 circuit board, pictured on the right. The only difference between revisions 8 and 9 is the pin labeling of the connectors HD1 and HD2. If your board is revision 8,...
  • Page 12 Instruction Manual MFJ-1272B Schematic...

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