Radio Shack HTX-212 User Manual download pdf (Page 5)

MFJ-1272M Instruction Manual

Throughs:

Connect all pins here except MICROPHONE AUDIO.

(unlabeled)

if you use external audio do not connect the radio

pins for Receive

3. Header HD3 controls the RECEIVE AUDIO to the

EXTERNAL SPEAKER. Place a push-on jumper on pins 2

and 3 if you want the external speaker "on" all of

the time., or on pins 1 and 2 if you want the

external speaker "off" when using the TNC.. Most

people prefer not to hear audio during packet. Set

this jumper to the positions desired, according to

your own preference.

4. Replace the top and screws.

External Audio

If your radio does not have RECEIVE AUDIO on the

microphone, we suggest the use of an interconnecting

cable to supply RECEIVE AUDIO to the TNC/MIC switch.

You would connect the cable from an External Speaker or

Headphones jack on your radio, to the AUDIO IN jack of

the TNC/MIC switch. Therefore no jumper connection

should be made for Receive on the pc board.

Using the method above for connecting RECEIVE AUDIO to

the TNC/MIC switch, will cut off the internal speaker

inside the radio. In this case, you must connect an

external speaker to the EXT. SPEAKER jack on the

TNC/MIC switch. Otherwise you will not be able to hear

any signals at all from your radio.

Jumper Configuration

Because there are so 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. The

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Radio Shack HTX-212 User Manual Page 5