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DisEqC Compatible LNB Bias Tee

These boards are still in a testing stage – as there is a lot of interest, I will have a small run of these made for anyone interested. Watch this space!

A universal input voltage (4V to 30V) DisEqC Compatible LNB Bias Tee with polarisation switching (13V/18V) and LO band switching (22 kHz tone).

LNB Bias Tee Schematic

A XL6009 boost module takes the input voltage and boosts it to a higher voltage. Then, an LM317 linear regulator drops this voltage to either 13V or 18V depending on the state of V/H pin. A 555 timer creates a 22 kHz tone if desired.

In it the default state, Q1 grounds the top of R4, such that just R3 is setting the output voltage with R9. In this configuration, the output voltage is 13V. With the V/H pin grounded, Q1 is turned off, and the output voltage is set to 18V by R3 and R4 in conjunction with R9.

The default state of LB/HB pin is pulled high, turning on Q2. This in turn holds the 555 timer in reset state, such that there is no output. When LB/HB pin is grounded, Q2 is turned off and the 555 timer comes out of reset, enabling the 22 kHz signal.

Bill of Materials

The list of materials:

CategoryQuantityReferencesValueOrder Code
PCB1LNB Bias Teecontact me
Case1Hammond 1551KTBU – 80 x 40 x 20mm ABS BoxRS 773-3101
Modules1M1XL6009 Boost ModuleeBay
Connector1LNB1F Connector – right angle through hole (75Ω)RS 700-9515
Connector1RADIO1SMA – right angle PCB bulkhead fitting (50Ω)RS 800-6936
Capacitors1C14.7 nF
Capacitors3C2-C3, C6100 nF
Capacitors1C41 nF
Capacitors1C51 uF
Resistors4R1, R6, R10-R1110 kΩ
Resistors1R2330 Ω
Resistors1R32.2 kΩ
Resistors2R4, R71 kΩ
Resistors1R56.8 kΩ
Resistors1R8100 Ω
Resistors1R9240 Ω
Integrated Circuits1U1NE555
Integrated Circuits1U278L05
Integrated Circuits1U3LM317T
Transistors2Q1-Q22N7000
Diodes1D1LED
Diodes1D21N4001
Miscellaneous1FU1500 mA polyfuse
Miscellaneous1J1DC power jack
Miscellaneous1J20.1″ DuPont header pins
Inductor1L1220 nH (or greater) choke
I used 1uH (SRF: 230MHz not ideal)
RS 909-7905
Inductor1L21.5 mH

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