DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB
4-3
4.5
Synthesizer OS-3, OS-3H)
For LOW BAND units (OSR-3H061 synthesizer):
•
Change the select jumpers, JU2, 3, 4 (See Table below).
LOW BAND JUMPER TABLE
–
Use only with Analog Board PCB 50038-03 (Version 03).
–
Table to be used only as a guideline in choosing correct setting.
Binary JU2 JU3 JU4
Freq. (Minimum)
C24 In
Freq. (Center)
C24 Middle
Freq. (Max)
C24 Out
3 O X
X *50.4
52.4
54.5
2 O X
O 52.9
56.45
59.1
1 O O
X 56.5
60.95 64.3
0 O O
O 61.7
67.6 72.3
* C24 is adjusted 2 turns from the bottom.
X = Installed
O = Open
4.5.1
VHF OS(R/T)-3H 29 - 71.4 MHz VCO Alignment
Refer to the "OS(R/T)-3H 29 - 71.4 MHz Analog Board Component Layout" diagrams and the
"OS(R/T)-3H 29 - 71.4 MHz Analog Board Schematic Diagram" in section 6 of this manual
Using a high impedance (10 M
Ω
) DC Voltmeter, measure the PLL control voltage at TP4
located on the synthesizer module analog board (top)
.
Access to TP4 is available through the
synthesizer top cover
.
Using a small standard blade screwdriver, carefully adjust the VCO fine
frequency "TUNE" trimmer capacitor C24 until a test point (TP4) voltage of approximately
+2.3 Vdc is obtained
.
PLL loop control voltages below approxi0.5 Vdc and above
approxi4.5 Vdc will indicate an "out of lock" synthesizer condition.
If a test point (TP4) reading of approxi2.3 Vdc is unattainable through adjustment of
C24, then the coarse frequency jumpers, JU2-JU4 require modification in order to pull the VCO
tune range within the adjustment range of fine tuning capacitor C24
.
The top synthesizer cover
must be removed in order to gain access to the coarse frequency jumpers
.
The coarse frequency
jumpers (JU2-JU4) may be considered to be a selectable binary weighted capacitor element with
JU2 being the most significant "bit" and JU4 being the least significant "bit"
.
The tuning
resolution size is
≈
12 pF (JU4)
.
If the tuning voltage remains higher than +2.3 Vdc, decrease the
tuning jumper setting by 1 "bit" position and re-adjust C24 in an attempt to a2.3 Vdc at
TP4
.
For example, if coarse frequency jumpers JU2-JU4 are all installed and represented by 111
then a decrease by 1 "bit" position (12 pF) is represented by a binary jumper selection of 110;
jumper JU4 is not installed and jumpers JU2, JU3 are installed
.
