CHASSIS PTBM133A4X

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Software for PTBM133A4X

Circuit Theory

Oscillator frequency VCO-frequency = Oscillator frequency (Q2) - F_IN
VCO-frequency = 20.105MHz - 2.55MHz = 17.555MHz @ Ch.1 Band 40
Output from BPF (T1 / T2) = Oscillator frequency (Q2) + VCO-frequency
Output from BPF (T1 / T2) = 20.105MHz + 17.555MHz = 37.660MHz @ Ch.1 Band 40
RX and TX frequency = Output from BPF (T1 / T2) - IF-frequency
RX and TX frequency = 37.660MHz - 10.695MHz = 26.965MHz @ Ch.1 Band 40

Programming Chart for PLL02A

Band	Ch.	F_IN	P0	P1	P2	P3	P4	P5	P6	P7	P8
40	1	2.55MHz	1	1	1	1	1	1	X	X	X
40	2	2.54MHz	0	1	1	1	1	1	X	X	X
40	3	2.53MHz	1	0	1	1	1	1	X	X	X
40	4	2.51MHz	1	1	0	1	1	1	X	X	X
40	5	2.50MHz	0	1	0	1	1	1	X	X	X
-
40	40	2.11MHz	1	1	0	0	1	0	X	X	X
-
-80	X	X	X	X	X	X	X	X	0	0	1
-40	X	X	X	X	X	X	X	X	0	0	1
40	X	X	X	X	X	X	X	X	1	1	0
80	X	X	X	X	X	X	X	X	1	1	0
120	X	X	X	X	X	X	X	X	1	1	0

Adjustment

Reading Point	Adjustment	Description	Value
PLL
TP2	VCO-Block Coil	VCO Voltage	4 Volt @ 27.185MHz
OSCILLATOR
U1 Pin 3	Check	Reference Oscillator	10.240MHz
TP1	CT1	RX AM -80 Band	19.880MHz
TP1	CT2	RX AM 40 and -40 Band	20.105MHz
TP1	CT3	RX AM 80 Band	20.330MHz
TP1	CT4	RX AM 120 Band	20.555MHz
TP1	CT5	RX LSB 40 Band	20.1035MHz
TP3	CT7	TX AM	10.695MHz
TP3	CT8	RX LSB	10.692MHz

Adjustment	Description	Value
RECEIVER
T8	RF Input
T9	RF Input
T10	RF Input
T11	1. IF	10,7MHz
T12	1. IF	10,7MHz
T13	AM IF	455kHz
T14	AM Detector	455kHz
T6	SSB IF	455kHz
T7	SSB Detector	455kHz
T18	FM Discriminator	455kHz
RV6	SSB AGC
RV10	Squelch
TRANSMITTER
T1	PLL Output to Converter	37.660 - 38.100MHz for CEPT
T2	PLL Output to Converter	37.660 - 38.100MHz for CEPT
T3	Transmitter Output AM	26.965 - 27.405MHz for CEPT
T4	Transmitter Output AM	26.965 - 27.405MHz for CEPT
T5	Transmitter Output AM	26.965 - 27.405MHz for CEPT
CT6	Transmitter Output USB/LSB	26.965 - 27.405MHz for CEPT
RV2	Bias Q8
RV11	AM/FM Output Power	10 Watt
RV3 and RV9	SSB Modulation	18 Watt p-p
RV1	FM Modulation	+/- 2kHz
RV12	AM Modulation	90%
RV5	Carrier at SSB	Adjust for minimum carrier leakage
METER
RV4	RF Power Meter	10 Watt
RV7	RF S-Meter	SSB (USB/LSB)
RV8	RF S-Meter	AM/FM

Microphone Connection

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

COMPONENTS

PTBM133A4X Schematic Diagram Frequency List for HAM International Multimode 3 VCO Block 2SC1969 Finale Transistor 2SC2166 Driver Transistor 2SC1675 RF Transistor AN7140 Audio Power Amplifier BA403 FM IF-Amplifier and Discriminator AN612 Balanced Modulator TA7310P Oscillator, Mixer and Amplifier PLL02A PLL Frequency Synthesizer

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 2SC1675 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 2SC1675 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 2SC1675 (Q16) with an 2SC2999 (or similar low noise and high gain transistor) to achieve this improved signal to noise ratio.
Re-Adjust T8 and T9 / T10
The gain will improved with more than 6dB with the same signal to noise ratio.