GAREX TWOMOBILE MK II Скачать руководство пользователя страница 2 | Manualshive

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GAREX TWOMOBILE MK II Скачать руководство пользователя страница 2

D R A F T

D R A F T

D R A F T

Garex Twomobile

2

Handbook

SECTION I

INTRODUCTION

The Garex Twomobile is a transmitter–receiver for operation in the 144–
146MHz amateur band.

The  receiver  is  fully  tunable  over  the  entire  band  and  is  capable  of
receiving  both  amplitude  and  frequency  (or  phase)  modulated  signals.  A
fully transistorised double superheterodyne design is used, incorporating a
squelch  circuit  to  eliminate  background  noise  in  the  absence  of  a  signal.
The  appropriate  detector  for  FM  and  AM  is  selected  by  a  switch  mounted  on
the  front  panel.  FM  reception  employs  an  integrated  circuit  quadrature
detector.

The transmitter has a nominal input power to the final power amplifier of
15

watts.

The

audio

and

oscillator/modulator

units

are

ful1y

transistorised; the multiplier/driver and. power amplifier stages use
quick–heat twin tetrodes. The modulation system (phase or amplitude) is
selected by a front-panel switch, which is independent of the receiver mode
switch, thus readily allowing cross–mode working.

The  equipment  is  designed  to  operate  from  a  nominal  12V  DC  supply,
conveniently  supplied  from  a  vehicle  battery.  For  fixed-station  use,  a
mains–driven  power  supply  delivering  12V  DC  (stabilised)  at  5  amps  maximum
is  required.  (Under  standby  conditions  the  current  consumption  is  about
0.25A.)

All of the operator’s controls are mounted on the front panel. An external
loudspeaker is used, any 3 to 5 ohm type being suitable.

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.

A.N. Martin

M1FDE <at> G0MWT <dot> ORG <dot> UK

This document is DRAFT and preliminary and details are tentative. It will
be updated WHEN I’ve MADE ONE WORK.

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Содержание TWOMOBILE MK II

Страница 1: ...D R A F T D R A F T D R A F T Garex Twomobile 1 Handbook GAREX TWOMOBILE MK II TWO METRE FM AM TRANSCEIVER OPERATING MANUAL ...

Страница 2: ...ulation system phase or amplitude is selected by a front panel switch which is independent of the receiver mode switch thus readily allowing cross mode working The equipment is designed to operate from a nominal 12V DC supply conveniently supplied from a vehicle battery For fixed station use a mains driven power supply delivering 12V DC stabilised at 5 amps maximum is required Under standby condit...

Страница 3: ...f fitted Dimensions 12 x 5 x 9 deep Weight l2 lbs 5 7kg Optional features Tone burst generator 1700 or 1750Hz Up to 6 transmit channels RECEIVER Sensitivity 1µV p d input for 500mW audio output with signal to noise ratio of 12dB Audio output 1 watt with less than l0 distortion Intermediate frequencies 1st IF 10 7MHz 2nd IF 455kHz with band pass block filter Squelch An electronic squelch circuit is...

Страница 4: ...an FET The second local oscillator is crystal controlled at 10 245MHz producing the second IF of 455kHz The second IF is amplified and passed through a bandpass block filter after which there are a further five stages of amplification Amplitude modulated signals pass via the detector and noise limiter to the mode selection switch Frequency modulated signals are taken from the fourth amplifier stag...

Страница 5: ...ing stage VT305 is used Transformer T302 in its collector circuit has two secondary windings which are connected respectively to the signal detector MR302 and the AGC detector MR303 The rectified output from MR303 is fed back via emitter follower VT306 as AGC bias to the RF stages VT1 VT2 and the IF amplifiers VT302 VT303 The rectified output from MR302 passes through the noise limiter MR304 the r...

Страница 6: ...rs The multiplier driver and power amplifier use quick heat tetrodes Phase Modulation 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 ...

Страница 7: ...hone is amplified by VT50I and VT502 coupled by T501 to the series diodes MR5OI and MR502 which limit the audio and hence the peak deviation After limiting the audio is taken through a lowpass filter integrated by R511 and C508 and via the peak deviation control VR501 to the variable capacitance diodes MR651 and MR653 AF Section amplitude modulation The microphone output is amplified as described ...

Страница 8: ...the transmitter valves The red TX lamp is connected in parallel with the energising coils of RLA and RLB and illuminates when the microphone switch is operated Reversed Polarity Protection A selenium rectifier MR702 is connected across the DC supply when the power switch is on and is normally non conducting If the supply polarity is reversed MR702 will conduct and blow one or both of the supply fu...

Страница 9: ... supply lead to the negative Reversal of these connections will blow one or both of the 7A fuses It is important to ensure that the correct rating and type of fuse is used as a replacement The supply voltage for alignment and test purposes is 13 2V measured at the input to the equipment Receiver Connect a 3 5 ohm loudspeaker to the terminal block on the outside of the rear panel With the 12V DC su...

Страница 10: ...ck heat valves to reach operating temperature then speak at normal voice level across the face of the microphone at a distance of 2 3 inches do not speak directly at the face of the microphone When first using a particular sntenna system the transmitter should be correctly loaded to the antenna as follows using field strength meter or reflectometer VSWR meter adjust the antenna trimmer accessible ...

Страница 11: ...ck the antenna and connections Receiver Locate the positive and negative supply inputs to each Rx board and check that the appropriate voltage is present Typical voltages at various points are shown on the circuit diagrams For the detailed alignment procedure refer to the receiver alignment chart Transmitter Typical voltages at various points are shown on the circuit diagram Voltages are ve refere...

Страница 12: ...D R A F T D R A F T D R A F T Garex Twomobile 12 Handbook ...

Страница 13: ...D R A F T D R A F T D R A F T Garex Twomobile 13 Handbook ...

Страница 14: ...D R A F T D R A F T D R A F T Garex Twomobile 14 Handbook SCHEMATICS ...

Страница 15: ...D R A F T D R A F T D R A F T Garex Twomobile 15 Handbook ...

Страница 16: ...D R A F T D R A F T D R A F T Garex Twomobile 16 Handbook ...

Страница 17: ...D R A F T D R A F T D R A F T Garex Twomobile 17 Handbook ...

Страница 18: ...o drop almost to zero Then C902 then charges at a rate controlled by C908 until the logic level is reached when the switching gates change and then block the passage of the tone The delay while C902 charges gives the length of the toneburst With switch S5 in the TONE ON position a toneburst will be transmitted automatically each time the PTT contact is operated Adjustment Using a suitable frequenc...

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