JM PA-80U User manual

UHF POWER AMPLIFIER
PA-80U
User Manual
Page 1/5

Multifunction display bar operating modes
Mode
Color
Type
Blink
Function
Power
measurement
Green
Bar-graph
No
Measure output power, 10Watt
increments
Power setting
display
Green
Bar-graph
Yes
Indicates actual power limit
(10,20,30,40,50,60,70,80Watt)
SWR
measurement
Green
Dot
No*
Shows VSWR
Error indicator
Red
Dot(s)
No
Indicates error condition
* Blinks on under/overrange
Pushbuttons function
Name
Function
RX LNA
Toggles operation of receiver pre-
amplifier (LNA)
TX PA
Toggles operation of transmit power
amplifier
SSB ON
Toggles SSB mode
SET POWER
Displays/changes transmit power limit
SHOW SWR
Enables SWR display
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Turning amplifier on and off
Transmit power amplifier and receiver preamplifier functions are independent on
each other. They can be toggled on/off by pressing respective pushbuttons: RX LNA
and TX PA. When function is enabled, LED associated with pushbutton is lit.
Amplifier is completely off, when both LEDs are dark.
Changing power level
Transmit power amplifier is equipped with Automatic Level Control loop (ALC).
Preset power is adjustable is 8 steps: 10W,20W,30W,40W,50W,60W,70W,80W. First
press of SET POWER button enters power setting mode. Multifunction display bar
blinks, showing preset power level. First press of SET POWER button, doesn't
change the level, but displays actual setting. Subsequent pressing of SET POWER
button change power setting. Amplifier exits power setting mode if SET POWER
button is not pressed again within 2 seconds.
Automatic Level Control is of saturated nonlinear type, only suitable for FM
modulation. While using amplifier with AM/SSB modulations, set ALC threshold to
maximum power (50W), then adjust transceiver power to yield appropriate power
displayed on bargraph. ForAM modulation, carrier power should not exceed 10-15W,
to accomodate modulation peaks without distortion.
In case of SSB modulation, observe bargraph which is of PEP type, keeping 50W
LED lit only ocassionally.
Turning SSB mode on/off
The SSB ON button toggles SSB mode on/off, actual state indicated by associated
LED. When SSB mode is enabled, carrier sensing algorithm, time delays, power
meter bar behaviour are changed to address modulation properties. There is no
difference in power amplifier biasing itself, since this modern desing is inherently
linear, unlike elder bipolar transistor based designs.
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Measuring VSWR
This useful function allows to accurately measure amplifier load VSWR. To enable
VSWR measurement, press SHOW SWR button while transmitting. This mode will
persist as long as amplifier is in transmit mode. Display returns to normal operation
(power measurement) after releasing transceiver PTT button.
Actual VSWR is represented as single „moving dot”. Lowest reading is 1.20, below
this value respective LED starts blinking, indicating underrange. Highest reading is
1.90, crossing 2.00 will cause respective LED blinking, indicating overrange.
Built in VSWR meter is of good quality, compensating for detector nonlinearities,
what makes measurement result fairly independent on output power. It also offers
exceptional directivity, with residual VSWR reading in order of 1.10.
Error signalling
To signal error in amplifier operation, multifunction display bar LEDs change color
to red. Apperance of any error denies power amplifier transmit operation.
Error LED
Meaning
Amplifier reaction
HIGH SWR
Excessive VSWR (over 2.1)
detected. Typically caused by
faulty antenna.
Deny transmitting, resume
after PTT release
OVERDRIVE
Excessive input power (>7Watt)
Deny transmitting, resume
after PTT release
DC VOLTAGE
DC supply voltage out of
permissible range (10.5V to 14.8V)
Deny transmitting, resume
after PTT release and voltage
restored
HIGH TEMP
Chassis temperature over 60 ºC
Deny transmitting, resume
after cooling down
PA FAIL
Amplifier electrical failure
Deny transmitting, resume
after PTT release
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Specifications: Power amplifier
Parameter
Min.
Typ.
Max.
Remarks
Frequency
range
430 MHz
470 MHz
Maximum
output power
75Watt
80Watt
85Watt
ALC limited
Input power
range
0.7 Watt
7 Watt
Between carrier detect and
overdrive thresholds
Input power for
full output
3 Watt
5 Watt
Frequency dependent
Bypass power
50 Watt
Harmonics
suppression
65dBc
Modulation
AM, FM, SSB
Circuit type
Twin MOSFET, PUSH-PULL
Specifications: Receiver preamplifier
In-band gain
13dB
15dB
15.5dB
430 MHz - 470 MHz
Noise figure
2.4 dB
3 dB
Specifications: General
DC supply
voltage
10.5 V
12.6 V
14.8 V
Operation at low end of range
may not yield specified
maximum power
Transmit
supply current
12 A
13A
Transmitting at maximum
power. Frequency dependent.
Standby supply
current
20 mA
All functions OFF
35 mA
TX PA enabled
80 mA
RX LNA enabled
88 mA
TX PA and RX LNA enabled
RF connector
UHF (SO-239)
Weight
1.15 kG
Dimensions
H=50mm, W=125mm, L=210mm
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