MFJ MFJ-434B Instruction Manual Download | Manualshive

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MFJ-434B Instruction Manual Voice Keyer

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Summary of Contents for MFJ-434B

Page 1: ...sceivers including Yaesu Icom and Kenwood Alinco radios Automatic Message Stop Microphone PTT switch automatically halts outgoing messages Manual Message Stop Prominent red STOP button halts outgoing messages Built in Amplifier Speaker Monitors outgoing messages and previews stored messages Two Microphone Sources Record from your station microphone for seamless audio continuity or use the built in...

Page 2: ...leads with ampere to 1 ampere fast blow fuses Power Supply 1 A 1 A WARNING Never insert the power plug with power applied an accidental short from to chassis ground may result Also never allow keyer supply voltage to exceed 16 Vdc Connections to high current power sources must be fuse protected MFJ 1312B Power Supply The MFJ 1312B wall adapter is also suitable for powering your voice keyer It come...

Page 3: ...ernal Mic Built in electret microphone location Mic Int Ext Selects internal in or external out microphone Xmit On Off Disables transmitter PTT line when reviewing messages Record LED Illuminates in record mode flashes during recording red Record Play Selects record mode in or play mode out Play LED Illuminates when selector is in play mode green Volume Controls volume of monitor speaker and audio...

Page 4: ...round microphone connector and a RJ 45 modular connector located on the front panel These are the same types used by most transceiver manufacturers Since manufacturers wire these 8 pin connectors differently the MFJ 434B provides a convenient jumper interface to program its connectors for use with different transceivers This feature eliminates the need for re wiring jacks or adding adapter cables ...

Page 5: ...4 JMP2 9 On the left side of the circuit board locate the set of headers JMP2 9 There are 8 possible configurations on each row of jumpers 2 9 See the jumper diagram below JMP 8 JMP 9 JMP 7 JMP 3 JMP 4 JMP 6 JMP 5 1 2 4 3 5 6 8 7 JMP 2 Mic Mic Mic Gnd Mic Gnd PTT PTT PTT Gnd Direct 5 Remove the jumpers on JMP2 9 ONLY 6 Replace the jumpers on JMP2 9 using the diagram specific to your radio located ...

Page 6: ... jmp 5 and jmp 6 on the pin number required by your microphone configuration This pin number can be determined from the front panel view above For example if your radio has PTT Grnd on pin 6 a jumper will be placed on jmp5 pin 6 and jmp6 pin 6 7 JMP5 Direct Place jumpers on jmp5 direct on remaining lines not configured above These pins will control up dn VDC squelch AF and other functions commonly...

Page 7: ...r s internal electret mic Both jack terminals float with respect to ground to permit connecting balanced or unbalanced sources If you experience station microphone hum with an external audio source plugged in install a 600 Ohm 1 1 audio isolation transformer in the external audio line RadioShack RS273 1374 All audio lines balanced or unbalanced should be grounded at one end only Stereo Plug Mono P...

Page 8: ...use the positive and negative lines Pre set your keyer s controls as follows Mic Int Ext Set as needed Int for built in mic or Ext for station s PTT mic Xmit Off out Rec Play Play out Volume 10 o clock position Power Off out Remember to power your transceiver before turning on the keyer Repeat Delay Fully counter clockwise CW for minimum delay X10 X1 X1 out Recording A Message 1 Press POWER to ON ...

Page 9: ...is nearly expired To conserve memory and prevent accidental over writing release the memory button immediately after your last word Message Memories The MSG storage space is actually one continuous block of memory with start cues inserted at 5 points along its span These form 5 message slots To use all 5 slots each entry must not exceed the times specified below MSG1 MSG2 MSG3 MSG4 MSG5 32 Seconds...

Page 10: ...ing Recorded Messages Whenever the Xmit button is On in any message MSG you select will be transmitted over the air 3 Single Play of a Recorded Message To preview or transmit a message one time only press the desired MSG switch briefly and release 4 Endless Loop Playback of a Recorded Message To preview or transmit a message in endless loop mode press and hold the desired MSG button for two second...

Page 11: ...keyer is in Play mode and activate the Xmit switch in Now activate your test message by pressing the appropriate MSG button The radio should key automatically when the message begins and drop out when it stops C Set Output Level Control Find the Output Level screwdriver adjustment on the back panel and adjust it so the transceiver s meter readings approximate those from live speech If your final a...

Page 12: ...External Control Circuits Lines available at the Remote IDC port permit installing an external remote control switch or PC computer interface This feature provides external control of voice keyer message buttons MSG1 MSG5 and Stop In addition a transmit warning line Xmit is available to signal external devices when the keyer is activating the transmitter Xmit is a 12 volt signal line sourced throu...

Page 13: ... interface is relatively immune to ground loops it takes almost 3 V RMS ripple to cause erratic control it is still a good idea to use careful wiring techniques We recommend using the interface circuit shown below to protect the computer from external RF Each 2N3904 transistor should be driven into saturation for reliable control This normally requires at least 5 mA of base current Locate the driv...

Page 14: ...ge and polarity of your power source it must be capable of providing 9 15 Vdc 100 mA If running on 9V internal battery check battery condition XMIT Function and Station Mic PTT Function won t work Check internal microphone jumper interface does it match the type of transceiver you are using Station Mic won t work Check the External Microphone Power Select Internal jumpers JMP6 must be set to the v...

Page 15: ...o system groundloop your keyer is heavily protected against RFI To eliminate RF feedback as the cause place the transmitter on a dummy load and run tests at full power level If the audio problem disappears it s probably RF related If not there s probably one or more groundloops in your station setup Groundloops happen when signal grounds mic lines audio output lines etc are inadvertently connected...

Page 16: ...MFJ 434B Instruction Manual Voice Keyer 16 NOTES ...

Page 17: ...Gnd Mic Gnd PTT PTT PTT Gnd Direct Kenwood TS TS TS 870 TS 2000 570 8 pin round 50 JMP 8 JMP 9 JMP 7 JMP 3 JMP 4 JMP 6 JMP 5 1 2 4 3 5 6 8 7 JMP 2 Mic Mic Mic Gnd Mic Gnd PTT PTT PTT Gnd Direct Kenwood TS 480 modular JMP 8 JMP 9 JMP 7 JMP 3 JMP 4 JMP 6 JMP 5 1 2 4 3 5 6 8 7 JMP 2 Mic Mic Mic Gnd Mic Gnd PTT PTT PTT Gnd Direct Icom IC 703 IC 706 modular JMP 8 JMP 9 JMP 7 JMP 3 JMP 4 JMP 6 JMP 5 1 2...

Page 18: ...MFJ 434B Instruction Manual Voice Keyer 18 Schematic ...

Page 19: ...MFJ 434B Instruction Manual Voice Keyer 19 ...

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