Low Noise Factory LNF-PS3b User manual

[e-mail]
lownoisefactory.com
Low Noise Factory AB
Nellickevägen 24,
412 63 Göteborg,
Sweden
Date
2023
-06-22
Manual
LNF-PS3b
Low Noise HEMT Power Supply

Manual
LNF
-PS3b
Low Noise
HEMT Power Supply
Date
2023
-06-22
[e-mail]
lownoisefactory.com
Low Noise Factory AB
Nellickevägen 24,
412 63 Göteborg
, Sweden
2
Contents
1. Introduction........................................................................................................................................................3
2. Specifications .....................................................................................................................................................3
3. Before Starting Use.............................................................................................................................................4
4. Wiring..................................................................................................................................................................4
5. Using the Instrument..........................................................................................................................................6

Manual
LNF
-PS3b
Low Noise
HEMT Power Supply
Date
2023
-06-22
[e-mail]
lownoisefactory.com
Low Noise Factory AB
Nellickevägen 24,
412 63 Göteborg
, Sweden
3
1. Introduction
LNF-PS3b is a compact power supply designed for LNF’s Low Noise Amplifiers. The drain voltage is regulated and
adjustable within a wide range, and the gate voltage is automatically and continuously adjusted to give a set drain
current. Vd and Id are displayed on the LCD monitor screen for easy bias control. Vg can be monitored for trouble
shooting through the banana sockets on the front panel using a multimeter. Vd and Id are set by trim
potentiometers on the front panel. The LNF-PS3b is redesigned from ground up and features new low noise
electronic components for much improved performance compared to previous models. There is also a drain
voltage sense function for situations where bias wire resistance is significant. The display can be switched off for
ultra-low noise operation. The power supply is powered by LNF’s Power Block, LNF-PBA.
The LNF-PS3b is delivered with a 1.5-meter cable to be used between the LNF-PS3b and the LNF-PBA. The part
number of this cable is LNF-CAB_PBA_PS3b. Also included is a 2-meter-long cable for the DC-output from the
LNF-PS3b. The PS3b end has a M12 connector and the other end of the cable is blunt for the end-user to solder
their connector to mate with their system. The part number of this cable is LNF-CAB_PS3b_LNA.
2. Specifications
Input
Parameter
Description
Minimum
Nominal
Maximum
Unit
+12V range
+12 V rail input voltage range
12
-
15
VDC
-12V range
-12 V rail input voltage range
12
-
15
VDC
Output
Parameter
Description/Conditions
Minimum
Nominal
Maximum
Unit
Vd range
0.00
2.40
VDC
Id range
0.00
65.00
mA
Vg range
-10
+10
V
Vd noise
Drain ripple and noise
3
mVPK-PK
Vg noise
Gate ripple and noise
3
mVPK-PK

Manual
LNF
-PS3b
Low Noise
HEMT Power Supply
Date
2023
-06-22
[e-mail]
lownoisefactory.com
Low Noise Factory AB
Nellickevägen 24,
412 63 Göteborg
, Sweden
4
Environmental
Parameter
Description/Conditions
Minimum
Nominal
Maximum
Unit
Storage Temperature
-40
85
°
C
Operating Temperature
5
40
°C
Relative Humidity
1
Non-Condensing
5
80
%RH
1The LNF-PS3b is for indoor use only, pollution degree 2.
Physical
Weight
354 g
Dimensions
98 (W) x 44 (H) x 99 (D) millimeters
3. Before Starting Use
After unpacking, make a visual inspection that there is no damage to the unit. If any damage is found, please
contact the factory prior to taking it into operation.
4. Wiring
The PS3b comes with a cable to connect it to the Power Block, LNF-PBA. This cable has a M8 female connector in
one end and a M8 male in the other end. It is possible to use the PS3b with a standard lab supply capable of
delivering +/-12 VDC. The maximum current from +12 V and -12 V is 150 mA and 25 mA respectively. If a third-
party supply is used to power the PS3b, then simply replace the female connector on the supplied cable with a
suitable one for the third-party power supply.

Manual
LNF
-PS3b
Low Noise
HEMT Power Supply
Date
2023
-06-22
[e-mail]
lownoisefactory.com
Low Noise Factory AB
Nellickevägen 24,
412 63 Göteborg
, Sweden
5
Pinout of M12 DC OUT Connector
Pin # Function
Wire Color
Cable V1
Wire Color
Cable V2
Wire Color
Cable V3
1
Vd
Blue
Brown
Black
2
Vd_sense+
Blue/White
White
Brown
3
Vd_sense-
Orange
Blue
Red
4
Vg
Orange/White
Black
Orange
5
GND
Green
Yellow/Green
Yellow
Shield
Earth
Foil
Foil
Foil
Pinout of M8 DC IN Connector
Pin #
Function
Wire Color of Included Cable
1
+12 V
TBD
3
-12 V
TBD
4
GND
TBD
Shield
Earth
Foil
The PS3b comes with a cable for the DC OUT connection to the LNA. It has a 5 pin M12 connector in one end while
the other end is blunt for the end-user to attach a suitable connector for their system. If the LNA to be powered
by the PS3b is for room temperature operation, solder the 9-pin nano-D connector pigtail connector to the open
end of this cable. For cryogenic LNAs, a connector compatible with your cryo cooler should be used. It is
recommended to not connect the shield in the LNA end. In the general case, the Vd sense function is not needed,
but if the cryo cooler is equipped with high resistance wires, the sense function could come in handy. It is
recommended to keep the actual Vds at the LNA terminals to +/-0.05 V of the nominal Vds. We can consider the
example when nominal Ids and Vds are 12 mA and 0.5 V respectively and the drain and ground wire resistance in
the fridge are 10 ohm each. We set Vds = 0.5 V and Ids=12 mA on the PS3b. The actual Vds at the LNA terminals
will be:

 = _ − × −  ×

 = 0.5 −10 × 0.012 −10 × 0.012

 = 0.26 
Where:

= the actual   at the LNA terminals

_=   supplied by the PS3b
= Drain wire resistance
= Ground wire resistance
Female connector seen
from connector side
Female connector seen
from connector side

Manual
LNF
-PS3b
Low Noise
HEMT Power Supply
Date
2023
-06-22
[e-mail]
lownoisefactory.com
Low Noise Factory AB
Nellickevägen 24,
412 63 Göteborg
, Sweden
6
In this example using the Vd sense function would ensure a properly biased LNA which performs maximally. Note
that if the power supply is not run in floating configuration (See section 6 in the manual for LNF-PBA), the ground
return current is likely to take a different path back to the power supply than through the 10 ohm ground wire. The
LNA’s DC-ground is connected to its chassis and the chassis likely connected to the ground of the fridge. In this
case, the voltage drop is likely to be about half of what it is in the example above.
 =0.05

The equation above can be used as a guideline of the maximum wire resistance Rmax (sum of drain and ground
resistance) allowed without having to pay special attention to compensating for the voltage drop. In the example
above, the maximum resistance is 4 ohm. In floating mode, this means 2 ohm in each of the drain and ground
wires.
If the Vd sense function is decided to be used, the Vd_sense+ wire should be connected to the drain pin of the
LNA close to the nano-D connector. The Vd_sense- wire should be connected to the ground pin of the LNA close
to the nano-D connector.
5. Using the Instrument
Once the wiring is done according to section 4, the instrument can be taken into operation.
FIRST TIME POWER UP
1. Connect the LNF-PS3b to the LNF-PBA with the included cable.
2. Ensure the LNF-PBA is in non-floating mode by installing the jumper plug between earth and common.
3. Switch on the LNF-PBA.
4. Switch on the LNF-PS3b.
5. Set Vds to nominal value of the LNA using the trim potentiometer on the front panel of the LNF-PS3b.
6. Switch off LNF-PS3b.
7. Connect the LNF-PS3b to the LNA.
8. Switch on the LNF-PS3b.
9. If floating mode is desired, remove the jumper plug from the LNF-PBA.
10. Adjust Ids to nominal value of the LNA using the trim potentiometer on the front panel.
11. If the Vdsense function is used, press and hold the Vdsense switch on the front panel. The display will
now show the actual Vds over the LNA.
12. While holding the Vdsense button pressed, adjust Vds to the nominal value of the LNA.

Manual
LNF
-PS3b
Low Noise
HEMT Power Supply
Date
2023
-06-22
[e-mail]
lownoisefactory.com
Low Noise Factory AB
Nellickevägen 24,
412 63 Göteborg
, Sweden
7
POWER DOWN
1. Ensure the jumper plug is installed on the LNF-PBA.
2. Switch off the LNF-PS3b using the main power switch.
3. Switch off the LNF-PBA using the mains switch.
SECOND TIME POWER UP
This procedure assumes everything is connected and voltages and currents set to nominal value of the LNA.
1. Ensure the jumper plug is installed on the LNF-PBA.
2. Switch on the LNF-PBA using the mains power switch.
3. Switch on the LNF-PS3b using the main switch.
4. Remove the jumper plug from the LNF-PBA if floating mode is desired.
Vg+ monitor banana socket
Vdsense
Vg- monitor banana socket
Id set trimmer
Vd set trimmer
Power
Display power switch
DC out connector
DC in connector
Main switch