CHASSIS EPT360014B

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Software for EPT360014B

Block Diagram for Alan 87

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 = f_off-set + N_fr
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

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 V	Frequency Counter	Dummy Load 50 ohm	Oscilloscope
	DC Amperemeter	RF SSG	AF SSG

Preparation alignment:


Clarifier	Mid.
SQ GAIN	Max.
AF GAIN	Max.
RF GAIN	Max.
MIC GAIN	Max.
MOD, S/RF	S/RF
NB/ANL	Off
Band	D
Channel	19 (27.185MHz)

Reading Point	Condition	Adjustment	Procedure
PLL
IC5 Pin 3	-	Check	10.2400MHz
TP2	Band:D, Ch.:40	L17	5,0 Volt
TP3	-	L18	Maximum on Oscilloscope
OSCILLATOR

13.560MHz X-tal
IC10 Pin 9	AM	L19	16.0400MHz
IC10 Pin 9	USB	L20	16.0425MHz
IC10 Pin 9	LSB	L21	16.0375MHz
IC10 Pin 9	TX AM	VR21	16.0400MHz (TX-Frequency)
14.010MHz X-tal
IC10 Pin 9	AM	L19	16.4900MHz
IC10 Pin 9	USB	L20	16.4925MHz
IC10 Pin 9	LSB	L21	16.4875MHz
IC10 Pin 9	TX AM	VR21	16.4900MHz (TX-Frequency)
14.460MHz X-tal
IC10 Pin 9	AM	L19	16.9400MHz
IC10 Pin 9	USB	L20	16.942525MHz
IC10 Pin 9	LSB	L21	16.9375MHz
IC10 Pin 9	TX AM	VR21	16.9400MHz (TX-Frequency)
All models:
TP5	TX AM	L26	10.6950MHz
TP6	RX USB	L27	10.6925MHz
TP6	RX LSB	L28	10.6975MHz

TP5	TX USB	VR7	SSB Modulator Balance

RECEIVER
	RX AM	L6 L7 L8	RF Input
	RX AM	L10 L11 L12	AM/FM/SSB IF
	RX AM	L3 L4	AM/FM IF
	RX FM	L5	Discriminator Coil (FM Demodulator)


TP1	RX USB	L1 L2	Noise Blanker IF

	RX USB	VR3	SSB Squelch
	RX AM	VR4	AM/FM Squelch
AM/FM S- Meter	RX AM	VR1
SSB S- Meter	RX SSB	VR2
TRANSMITTER
TP9 (+) TP8 (-)	Bias Driver	VR11	10mA
TP9 (+) TP7 (-)	Bias Finale	VR10	100mA
TP9 (+) TP7 (-)	Bias Finale	VR20	100mA
	TX AM	L42	Maximum
	TX AM	L43	Mixer Coil (VCO-frequency input)
	TX AM	L44	Mixer Coil (TX-carrier 10.695MHz input)
	TX AM	L40 L42	Maximum RF output
	TX AM	L33	Minimum Harmonic
	TX AM	VR13	15 Watt (30 Watt with Dual Finale output) AM/FM
	TX USB	VR12	20 Watt (40 Watt with Dual Finale output) SSB (ALC)
	TX AM	VR14	90% AM-Modulation (AMC)
	TX FM	VR5	2 kHz FM-Deviation
	TX CW	VR16	CW Tone (Not in all model`s)
Power Meter	TX AM	VR8

Microphone Connection

Pin	Description
1	Ground
2	Microphone
3	TX Key (Connect to Ground)
4	Speaker (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 SynthesizerS042P TX Mixer KIA6410S Oscillator, Mixer and Amplifier uPC1028H FM IF Amplifier and Detector AN612 Balanced SSB Modulator TA7222 Audio Power AmplifierNJM4558 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.