Before Alignment; Main Reference Frequency Adjustment; Transmit Power Adjustment - Standard Horizon HX280S Service Manual

Alignment

Before Alignment

Install the HX280 Service Flag Controller Program to
your computer.
Remove the Front Panel from the transceiver accord-
ing to the following procedures:
1) Disconnect the antenna from the transceiver.
2) Remove the VOL knob and Battery Pack from the
transceiver
3) Remove the two screws which located at the bot-
tom side on the battery compartment.
4) Carefully pull out the chassis from the Front Panel.
Refer to the "Exploded View" on the page 4.
Set up the test equipment as shown below, and set the
DC Power Supply voltage to 7.4 V.
Execute the HX280 Service Flag Controller Program.
Select the COM port number which is connected to
the HX280 Alignment Jig.
Press and hold in the [ PRESET ] key
while turning the transceiver on to
enter the Alignment Mode.
Select "Alignment ON" Radio But-
ton of the HX280 Service Flag Con-
troller Program.
Click the left mouse button on the
[ SET ] button of the HX280 Service
Flag Controller Program.
Inline RF Sampling
Wattmeter
Coupler
50
Ω
Dummy Load
Frequency
Counter
Regulated
Power Supply
10
Antenna Switch
"TX" Alignment
VR1002
VR1003
VR1001
( ) : ( ) :
RED RED
( ) : ( ) :
BLACK BLACK
HX280 Alignment Jig

Main Reference Frequency Adjustment

Turn the Antenna switch to the "TX Alignment" side.
Remove the solder jumper JP1001.
Set the channel to CH16.
Use the [ H/L ] key to set the transceiver to "LOW"
power.
With the PTT switch pressed, adjust TC1001 so the
Frequency Counter reading is 156.800 MHz ± 100 Hz.

Transmit Power Adjustment

Turn the Antenna switch to the "TX Alignment" side.
Set the channel to CH16.
Increase the DC Power Supply voltage to 8.0 V.
Use the [ H/L ] key to set the transceiver to "HI" power.
With the PTT switch pressed, adjust VR1003 so that
RF output power is 5.0 W ± 0.1 W.
Release the PTT switch, then set the transceiver to
"LOW" power by the [ H/L ] key.
With the PTT switch pressed, adjust VR1002 so that
RF output power is 0.8 W ± 0.1 W.
Release the PTT switch.
Return the DC Power Supply voltage to 7.4 V.
RF Signal
Generator
"RX" Alignment
Attention!
The HX280's Audio output is BTL output.
16 1 W
Ω
Resistor
AF Signal
Generator
JP1001
TC1001
VR1005
TP1018
D-SUB 9-pin Jack