Nissei DG-503 User manual

NISSEI
SERVICE MANUAL
DG-503
RANGE : 1.6 - 525 MHz
Max. Power : 200W

SERVICE MANUAL
TABLE OF CONTENT
MODEL : DG-503 SWR & POWER METER 1.6-525 MHz
SECTION SUBJECT:
1. INTRODUCTION
1.1 Main features.....................................................................................
2
1.2 Specification............................................................................ 2
2. ALIGNMENT
2.1 Test equipment.............................................................................. 3
2.2 Forward power (125-525Mhz)............................................................
3
2.3 SWR alignment (125-525Mhz)...........................................................
4
2.4 Forward power (1,6-60Mhz)...............................................................
4
2.5 SWR alignment (1.6-60Mhz)..............................................................
4
2.6 Final alignment............................................................................... 4
2.7 Alignment spots photo……………………………………………… 5
3. SCHEMATICS & COMPONENT PLACEMENT
3.1 Main board schematic ………………………………………………………
6
3.2 Main board component placement 7
4. EXPLODED DRAWING & PARTS LIST
4-1 EXPLODED DRAWING .......................................................................
8
4-2 PARTS LIST…………………………………………………………………
8
- 1 -

1. INTRODUCTION
This digital SWR & Watt meter is highly accurate for measuring
Forward Power,Reflected Power, & VSWR.
1.1 Main Features:
A. Large LCD (3.5") display for easy of reading.
B. Forward / Reflected power / VSWR ratio in one push button.
C. LCD backlight display
D. Convenient control layout for easy operation
E. Packing gift box and DC 12V wire.
1.2 SPECIFICATIONS
MODEL DG-503
Frequency Range 1.6-60 MHz / 125-525 MHz
Caibration point 14MHz / 50MHz / 145MHz / 435MHz
Power Range 0 - 200W
Accuracy (+/- 5%)
Minimum Power for SWR 1W
Input/Output Connector SO239 (N-female option)
Weight (Net) 750 g
Insertion Loss Less than 0.1 dB
Testing Function Fwd/Ref Power & VSWR ratio
Input/Output Impedance 50 Ohm
Dimension (W/H/D) mm 140 x 84 x 122
Accessories Operation Manual, 12V DC Wire
<FRONT PANEL>
1 2 <FRONT & REAR PANEL>
1. LCD Display : Indicates FWD/REF and VSWR
2. HF & V/UHF band switch.
3. Power switch
3
<REAR PANEL> <REAR PANEL>
5.TX connector : Coax connector to transmitter RF output
6. ANT connector : Coax connector to antenna system
7. Power source :13.8V DC wire
[ Black line is negative (-), black/white line is positive (+) ]
- 2 -

2. Alignment
2.1 Test Equipment
A. HF transceiver
B. VUHF dual band transceiver
C. VHF Power amplifier ( VHF ), Input 5-20W, Output 200W
D. UHF power amplifier ( UHF), Input 5-20W, Output 200W
E. Power Supply 13.8, 50A
F. Dual Band Antenna ( MAX. 200W )
G. HF Antenna ( MAX, 200W )
H. Power meter BIRD 4421 or BIRD 43
I. Dummy Load 50 OHM, MAX. 200W X1, 25 OHM, MAX, 200W x 1
J. Ceramic adjusting driver
2.2 Forward Power alignment (125-525 MHz coupler & PCB adjustment)
Preset : Turn DG-503 switch to "VUHF", connect coupler plug to
JP2 on C board
A. Turn dual band transceiver to VHF 145.130 MHZ position "M"
Connect BIRD 4421 + dummy load. Record forward power and
SWR from BIRD 4421
B. Turn dual band transceiver to UHF at 435.130 MHz ; position " M"
Connect BIRD 4421 + dummy load. Record forward power and
SWR from BIRD 4421
C. Turn DG-503 to VUHF (DG-503 replace BIRD 4421)
D. Press PTT, adjust CV1 on coupler until the reading of forward power
is same as record from point B.
E. Turn transceiver to VHF at 145.130 MHz, position "M"
F. Press PTT, adjust R3 UVFWD on PCB board, get the same readings
recorded from point A
G. As CV1 and R3 UVFWD might interfere each other, repeat step
D & F until correct readings for V and U range are gotton.
H. When adjustments made in step D and/or F, re-alignment A-G is
essential to meet 5% tolerance
- 3 -

2.3 SWR alignment (125-525 MHz)
A. Connect transceiver TX to DG-503 TX ; antenna to DG-503 ANT
B. Turn transceiver to UHF 435.130 MHZ, position "M''
C. Refer to 2.1 step B SWR value ; adjust CV2 in coupler to get same
SWR reading from DG-503
D. Turn transceiver to VHF 145.139 MHZ, position "M''
E. Refer to 2.1 step A SWR value ; adjust R4 UVREV on the PCB
to get same SWR reading from DG-503
F. As CV2 and R4 UVREV might interfere with each other, repeat
step C and E uill a correct reading for V and U range are gotten.
G. When adjustments made in step C and/or E, re-alignment A-G is
essential to meet 5% tolerance
2.4 Forward power alignment (1.6-60 MHZ)
A. Turn HF transceiver to 28.5 MHz, connect BIRD 4421 + DG-503 +
50 Ohm dummy load.
B. Turn DG-503 switch to "HF", connect coupler plug into JP1 on PCB
C. Push PTT, tune transceiver power to get "100W" shown on
BIRD 4421
D. Use ceramic driver to adjust R2 HFFWD on the PCB until DG-503
reading 100W is shown
;2-5 SWR alignment (1.6-60 MHz)
A. Turn HF transceiver to 28.5 MHz, connect BIRD 4421 + DG-503 +
25 Ohm dummy load.
B. Set DG-503 to HF range
C. Push PTT, record SWR value which is shown on BIRD 4421
D. Use ceramic driver to adjust R1 HFREV on PCB until same SWR
reading shown on DG-503.
2.6 Final alignment
PCBs (board A, B, &C) were aligned seperately before assembly.
After DG-503 completed assembly, it is a must for the calibrator to do
a final check on every calibration point mentioned above to assure
DG-503 accuracy
- 4 -

2.7 Alignment spots photo (PCB-C driver board)
- 5 -

3. SCHEMATIC
3.1 Main board schematic
- 6 -

3.2 Main board component placement
- 7 -

4. EXPLODED DRAWING & PARTS LIST
4-1 EXPLODED DRAWING
4-2 PARTS LIST
No Name Description QTY
1Plate Name plate 1
2Plate Function plate 1
3Switch Slide 1
4Panel Plastic front panel 1
5Lens PMMA 1
6Display LCD display 1
7Backlight LED backlight sheet 1
8Button Push button 1
9PCB PCB_B_Main Board 1
10 Screw 6
11 PCB PCB_C_Driver Board 1
12 PCB PCB for slide SW 1
13 Sensor x2, HF and V/U HF 2
14 Socket 13.8V 1
15 Screw 6
16 Chassis Base cabinet 1
17 Stand Rubber stand 4
18 Screw 4
19 Screw 4
20 Chassis Top cabinet 1
- 8 -

Brand: Nissei
Type: DG503
Complaint: Bad read out or 000 read out
-----------------------------------------------------------------------------------------------------------------
If the display shows 000, pls refer to the photo and apply fully soldering at
the said 5 points.