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MFJ -1272M Instruction Manual

Tnc/microphone switch
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MFJ-1272M TNC/MICROPHONE SWITCH
Introduction
Thank you for purchasing the MFJ-1272M TNC/MIC Switch.
The
MFJ-1272M
is
connection of both your microphone and your TNC to the
radio.
The MFJ-1272M microphone switches were designed to be
used with any radio that has an 8-pin, RJ-45 modular
microphone connector.
connectors, MFJ offers 5 models:
MFJ Model#
TNC and Multimodes
MFJ-1272M
All MFJ TNCs, TAPR TNC-2 clones, and PK-
12/96/900
MFJ-1272MX
PK-232
MFJ-1272MYV
KAM® VHF port, KPC-9612, KPC-2, KPC-3
MFJ-1272MYH
KAM® HF port
MFJ-1272MZ
PK-88
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.
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.
your
responsibility
connections will not damage the radio.
designed
to
allow
Because many TNCs have different
to
make
simultaneous
You could
It is
sure
your

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Summary of Contents for MFJ MFJ-1272M

  • Page 1 MFJ-1272M TNC/MICROPHONE SWITCH Introduction Thank you for purchasing the MFJ-1272M TNC/MIC Switch. MFJ-1272M designed allow simultaneous connection of both your microphone and your TNC to the radio. The MFJ-1272M microphone switches were designed to be used with any radio that has an 8-pin, RJ-45 modular microphone connector.
  • Page 2 MFJ-1272M Instruction Manual KAM® is a registered trademark of Kantronics Company, Inc.
  • Page 3 TNC/MIC switch your radio, please follow this procedure. 1. Remove the two screws and top cover of the MFJ- 1272M. 2. Look at the writing on the unit's pc board. Please refer to Tables 1 thru 6 as to where to place the jumpers in relation to the pinouts on you radio.
  • Page 4 MFJ-1272M Instruction Manual Audio from the radio to the TNC. Please refer to the External Audio section on the following page. If you use external audio make no connection here. MIC Audio: Audio from mic (same # as Audio Out) Ground: This is the system ground on radio's mic connector.

  • Page 5: External Speaker

    Jumper Configuration Because there many different radio configurations, we have tried to make the MFJ-1272M as versatile as possible. With the MFJ-1272M you can virtually connect any radio pin to just about any TNC pin, just by configuring the jumpers properly.
  • Page 6 MFJ-1272M Instruction Manual following tables will show how to set the jumpers, depending on the TNC functions versus the MIC pins of your particular radio. Be sure to follow the tables closely, with your radio manual close hand, verify that...
  • Page 7 MFJ-1272M Instruction Manual Receive Audio Connections Table 1 below shows where you would place a jumper if your radio has RECEIVE AUDIO on one of the microphone pins. For example, if your radio has RECEIVE AUDIO on pin 3 on a Kenwood microphone, you would place a jumper on position R3A in the RECEIVE section of header HD1.
  • Page 8 MFJ-1272M Instruction Manual PTT--R7B PTT--R2B PTT--R8B PTT--R1B Table 2...
  • Page 9 MFJ-1272M Instruction Manual Audio Out Connections Table 3 below shows where you would place a jumper, depending on what microphone pin is designated MIC. The microphone designated MIC, is the pin that the transmit audio from the TNC comes into the radio.
  • Page 10 MFJ-1272M Instruction Manual Tabel 4 Always use the MIC pin designated as GROUND (not mic ground). The use of MIC GROUND could result in audio "hum" in the system.
  • Page 11 3 is designated as being UP, which would be for increasing your frequency readout on the radio, then would place jumper header position on the MFJ-1272M PC board labeled R3E-M3A. Radio MFJ-1272M Jumper Placement Jumper Placement MIC Pin Header for Kenwood &...
  • Page 12 MFJ-1272M Instruction Manual AUDIO IN--M6B AUDIO IN--M3B AUDIO IN--M7B AUDIO IN--M2B AUDIO IN--M8B AUDIO IN--M1B Table 6 *Refer to External Audio, page 3...
  • Page 13 1272M correctly, is to have your transceiver manual handy at the time of setup. Having your transceiver manual handy will ensure that you setup the MFJ-1272M properly, by making the right connections the first time. If you find yourself in need of technical help, please...
  • Page 14 MFJ-1272M Instruction Manual Jumper Placement Diagrams for specific radios...
  • Page 15 In this case, the MFJ-1272M is totally incompatible. If you want to use the MFJ-1272M with an Icom or Radio Shack transceiver, then all jumper designations need to be thought of in reverse order. This is due to the...
  • Page 16 MFJ-1272M Instruction Manual...
  • Page 17 2. Connect the gray, 8-pin MIC plug, which exits the rear of the MFJ-1272M out of the TO RADIO slot, to the microphone jack on the radio. 3. Connect the TNC cable, which exits the rear of the MFJ-1272M out of the TO TNC slot, to the TNC.
  • Page 18 MFJ-1272M Instruction Manual 3.5mm mono plug, with the tip being positive and the sleeve ground.
  • Page 19 You will be best helped if you have your unit, manual and all information on your station handy so you can answer any questions the technicians may ask. You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial Park Road, Starkville, MS 39759; Facsimile 601-323-6551;...
  • Page 20 MFJ-1272M Instruction Manual Schematic...

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