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CHASSIS EPT360014B


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Software for EPT360014B



Block Diagram for Alan 87

Block Diagram
PLL Circuit. PLL is an abbreviation of the phase-locked loop which is fundamentary composed of a closed loop feedback citcuit. The feedback component is the balance of frequency drift and the PLL circuit acts to cancel it out. To detect out the frcquency drift of the PLL output, a fixed reference ocillator (10 kHz, 1/1024 divided down from 10.240 MHz) is compared constantly with the input frequency (10 kHz). The input frequency is obtained by dividing the VCO frequency.

Off-Set frequency oscillator IC10. The off-set-frequency oscillator IC10 oscillates at 14.460MHz for all band. Switching between these oscillating frequencies is made by biasing the diodes D34 to D36.
The off-set frequency signal is obtained at IC10 Oscillator and flows into IC10 Mixer where it is beat with the VCO signal. The VCO signal is obtained from the following:
f vco = foff-set + Nfr
Where, f vco = VCO frequency, N = programming code for divider output, and fr = referency frequency step (10kHz).

i.e.: At channel #1 in band A, and band corresponding N code is 91:
f vco = 14.010 + ( 91 x 0.01) = 14.920MHz.

Since the mixer output determined by two factors the off-set frequency output (dependent on band selector switch) and the VCO output, the mixer output contains the subtracted frequency of 0.91 to 2.25 MHz. These frequencies appears in pin #2 of IC5, and divided by the programmable divider in IC5 down to 10 kHz which is compared with another 10kHz signal obtained from the reference oscillator TR24 (10.240MHz).
The VCO output is mixed with the off-set frequency signal and applied to the TX mixer IC9 through band-pass filters.
i.e. At channel 1 in band A, and AM band, the TX mixer IC9 accepts 14.920 + 10.695MHz = 25.615MHz is TX frequency.
When receiving channel 1 in band A (26.065MHz), the 1st RX mixer TR18 accepts 15.370 localsignal at its base, and converts down it down to 10.695MHz IF (for AM/FM mode, this is the 1st intermediate frequency). TR18 off-sets the 10.695MHz signal so that TR30 can oscillate at 10.6975MHz for LSB.

CIRCUIT DESCRIPTION and BLOCK DIAGRAM for Cherokee CBS-2100

Block Diagram for Galaxy DX33, 44, 55, and 66

Block Diagram for Galaxy DX88

Block Diagram for Galaxy DX99


Adjustment

EPT360014B PCB

PLL and CPU PCB
In some model`s the PLL-circuit on Main PCB is replaced by a separate CPU and PLL board.
EPT360014B PCB


Decoder Board
In some model`s the decoders (MC14008) on Main PCB is replaced by a separate EPT004410Z board.
EPT004410Z PCB

Test equipment required:
Power Supply: 13,8 VFrequency CounterDummy Load 50 ohmOscilloscope
DC AmperemeterRF SSGAF SSG

Preparation alignment:


ClarifierMid.
SQ GAINMax.
AF GAINMax.
RF GAINMax.
MIC GAINMax.
MOD, S/RFS/RF
NB/ANLOff
BandD
Channel19 (27.185MHz)
Reading PointConditionAdjustmentProcedure
PLL
IC5 Pin 3-Check10.2400MHz
TP2Band:D, Ch.:40L175,0 Volt
TP3-L18Maximum on Oscilloscope
OSCILLATOR
13.560MHz X-tal
IC10 Pin 9AML1916.0400MHz
IC10 Pin 9USBL2016.0425MHz
IC10 Pin 9LSBL2116.0375MHz
IC10 Pin 9TX AMVR2116.0400MHz (TX-Frequency)
14.010MHz X-tal
IC10 Pin 9AML1916.4900MHz
IC10 Pin 9USBL2016.4925MHz
IC10 Pin 9LSBL2116.4875MHz
IC10 Pin 9TX AMVR2116.4900MHz (TX-Frequency)
14.460MHz X-tal
IC10 Pin 9AML1916.9400MHz
IC10 Pin 9USBL2016.942525MHz
IC10 Pin 9LSBL2116.9375MHz
IC10 Pin 9TX AMVR2116.9400MHz (TX-Frequency)
All models:
TP5TX AML2610.6950MHz
TP6RX USBL2710.6925MHz
TP6RX LSBL2810.6975MHz
TP5TX USBVR7SSB Modulator Balance
RECEIVER
RX AML6 L7 L8RF Input
RX AML10 L11 L12AM/FM/SSB IF
RX AML3 L4AM/FM IF
RX FML5Discriminator Coil (FM Demodulator)
TP1RX USBL1 L2Noise Blanker IF
RX USBVR3SSB Squelch
RX AMVR4AM/FM Squelch
AM/FM S- MeterRX AMVR1
SSB S- MeterRX SSBVR2
TRANSMITTER
TP9 (+) TP8 (-)Bias DriverVR1110mA
TP9 (+) TP7 (-)Bias FinaleVR10100mA
TP9 (+) TP7 (-)Bias FinaleVR20100mA
TX AML42Maximum
TX AML43Mixer Coil (VCO-frequency input)
TX AML44Mixer Coil (TX-carrier 10.695MHz input)
TX AML40 L42Maximum RF output
TX AML33Minimum Harmonic
TX AMVR1315 Watt (30 Watt with Dual Finale output) AM/FM
TX USBVR1220 Watt (40 Watt with Dual Finale output) SSB (ALC)
TX AMVR1490% AM-Modulation (AMC)
TX FMVR52 kHz FM-Deviation
TX CWVR16CW Tone (Not in all model`s)
Power MeterTX AMVR8

Microphone Connection

PinDescription
1Ground
2Microphone
3TX Key (Connect to Ground)
4Speaker (Connect to Ground)

Dual Finale output modification

Frequency List for Alan 87


COMPONENTS

Alan 87 Schematic Diagram
Cherokee CBS-2100 Schematic Diagram
Galaxy DX73V Schematic Diagram
Galaxy DX88HL Schematic Diagram
Cobra 148GTL-DX Schematic Diagram
MC145106P PLL Frequency Synthesizer
S042P TX Mixer
KIA6410S Oscillator, Mixer and Amplifier
uPC1028H FM IF Amplifier and Detector
AN612 Balanced SSB Modulator
TA7222 Audio Power Amplifier
NJM4558 Dual Operational Amplifier
TA6324 Quad Operational Amplifier
2SC1969 RF Finale Transistor (SuperStar 3900)
2SC2312 RF Finale Transistor (Alan 87)
2SC2166 RF Driver Transistor
2SC2086 RF Pre-Driver Transistor
2SB754 LF Power Transistor
2SA473 LF Power Transistor

Improved receive gain

Quieting of AM reception and improving gain of incoming signals is a common request from radio operators. In the first stages of the HF input 2SC1674 transistor can be found. This transistor is responsible for the amplification of a small detected signals. A problems exist if the transistor itself is noisy as is such the case of the 2SC1674 when compared to other low noise packages. Along with the amplification of the incoming signals is transistor noise. Replacement of this transistor with a higher gain, lower noise transistor greatly improves the signal to noise ratio of your receiver.
We will use an 2SC2999 transistor that has higher gain lower noise characteristic. Replace the 2SC1674 (TR17) with an 2SC2999 (or similar low noise and high gain transistor) to achieve this improved signal to noise ratio.
Re-Adjust L6 and L7
The gain will improved with more than 6dB with the same signal to noise ratio.