Summary of Contents for GAREX TWOMOBILE MK II
- Page 1 D R A F T D R A F T D R A F T GAREX TWOMOBILE MK II TWO-METRE FM/AM TRANSCEIVER OPERATING MANUAL Garex Twomobile Handbook...
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Page 2: This Document
THIS DOCUMENT This handbook was produced by M1FDE using notes and manuscript supplied by GAREX which I asked if I could publish. This is almost the document they would have published, but publishing this document is my responsibility and all communications regarding errors or further information should be addressed to M1FDE. - Page 3 TRANSMITTER Power 15 watts input (nominal) to the final power amplifier stage. Modulation a) High level amplitude modulation. b) Phase modulation, adjustable up to 15kHz deviation, normally set to ±3kHz. Garex Twomobile Handbook...
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Page 4: Circuit Description
The resultant audio is fed to the mode switch. From this switch the audio passes via the squelch gate to the audio amplifier and output stages. Garex Twomobile Handbook... - Page 5 VT503 and coupled via the emitter—fo1lower VT501, to the driver VT505. Phase splitting transformer T502 in the collector of VT505 drives the push—pull output stage VT505, VT507. T503 is the loudspeaker output transformer. Garex Twomobile Handbook...
- Page 6 The output from the crystal oscillator is phase modulated by the variable capacitance diodes and multiplied by the following stages. Amplitude Modulation The AF section (part of which is used in the receiver) provides anode and screen modulation of the transmitter power amplifier. Garex Twomobile Handbook...
- Page 7 R515 and R516 is shorted out by S3a effectively blocking the passage of audio amplitude modulation stages. amplitude modulation position, S3b shorts the peak deviation control VR5O1, preventing audio from reaching the variable capacitance diodes MR651 and MR653. Garex Twomobile Handbook...
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Page 8: Power Supply Section
RLB2 transfers the input connection to the audio amplifier (VT503) from the receiver volume control to the output from microphone preamplifier (VT502). RLB3/RLB4 transfers the AF output from the loudspeaker transformer T503 to the modulation transformer T504. Garex Twomobile Handbook... -
Page 9: Operation
When receiving frequency modulated signals having a deviation in excess of ±5kHz some distortion will result. To silence the Rx noise in the absence of a signal turn the squelch control carefully anticlockwise until muting just occurs. Garex Twomobile Handbook... - Page 10 20% (see Tx adjustments). Adequate ventilation, especially of the PA and driver area is essential. Garex Twomobile Handbook...
- Page 11 The transmitter should maintain its performance over a bandwidth of about 500kHz. Some adjustments to the tuning of the RF stages will be necessary when changing to a different segment of the 2 metre band. Refer to the transmitter alignment chart for details. Garex Twomobile Handbook...
- Page 12 D R A F T D R A F T D R A F T Garex Twomobile Handbook...
- Page 13 D R A F T D R A F T D R A F T Garex Twomobile Handbook...
- Page 14 D R A F T D R A F T D R A F T SCHEMATICS Garex Twomobile Handbook...
- Page 15 D R A F T D R A F T D R A F T Garex Twomobile Handbook...
- Page 16 D R A F T D R A F T D R A F T Garex Twomobile Handbook...
- Page 17 D R A F T D R A F T D R A F T Garex Twomobile Handbook...
- Page 18 Set S5 in the ‘TONE (ON)’ position and operate the PTT contact. Adjust RV901 for the required frequency, typically 1750Hz. R911 should be adjusted to give the required carrier deviation, having first set RV501 for normal speech levels. Garex Twomobile Handbook...