10GHz LNB with EXT OSC manual

This is a new version (MK3) of the Low Noise Block (LNB) with external reference and Bias Tee box with better filtered reference frequency using X-tal filters. Crystal filters are in both the Bias Tee box and the LNB. The result is better phase noise and output (IF) signal quality even when using a worse external reference signal source of 10MHz.

In addition to the Crystal filters, the new Bias Tee box includes a new diplexer to separate the IF and reference (25MHz) frequencies on a single coaxial cable along with a DC power supply for the LNB.

The box also includes surge protectors, a current Super-Fuse, a new electronic DC fuse, LED indication of switching from V to H polarization and a continuously adjustable variable Attenuator.

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Technical parameters
Options: Recommendations to buy
Previous versions
Product details


- special SAT experiments
- Starlink experiments (mdpi.com)
- University Ku band projects
- Coherent receivers
- QO-100 Es'Hail satellite
- EME 10GHz
- SatTV DXing

block diagram of the Bias Tee box

lnb bias tee box block diagram by qro.cz hamparts.shop

signal source external 10 MHz
This is default preset configuration - if you like to use TCXO, please open the box and reconfigure jumpers

lnb bias tee box signal source external 10mhz by qro.cz hamparts.shop

trimmer works as variable attenuator

lnb bias tee box trimmer variable attenuator by qro.cz hamparts.shop

lnb bias tee by qro.cz hamparts.shop

lnb bias tee  by qro.cz hamparts.shop

power supply cable

power supply cable by qro.cz hamparts.shop

Bias Tee LNB BOX

- small box works as DC Bias Tee, 25 MHz source for LNB, variable ATT and protections
- allows you to supply DC voltage and 25 MHz reference for PLL of LNB over one coax
- you can use internal TCXO with 0.2 ppm or some 10 MHz reference signal (you can select signal by the jumper JP1)
- you can switch H and V polarisation
- DC and RF protections!
- Variable attenuator! (blue trimmer works as variable attenuator)
- DC plug included

Poty dual band antenna adapter

- PETG UV stable material
- 22 mm Cu pipe size (use tape to waterproof it)
- POTY pipe WG fixed by M4 screw
- ONLY ADAPTER, 2.4 GHz antenna NOT included!

poty dual band antenna adapter qro.cz hamparts.shop

Technical Parameters

LNB local oscillator 9750 MHz (with 25 MHz source)
Conversion gain of LNB > 50 dB @ 700 MHz
LNB IF 739 MHz for 10489 MHz (QO-100)
618 MHz for 10368 MHz
Reference 10 MHz input power -3 dBm to +13 dBm
Stability with 10 MHz reference depends on reference source
Stability with 25 MHz TCXO (0.2 ppm) 0.2 ppm (X 390)
25 MHz cut off to RX output port > 50 dB
Frequency error with TCXO max 3 kHz, typ. less than 1 kHz (after 5 minutes)
DC power +12 V for Vertical polarisation (NB)
+18 V for Horizontal (WB)
Bias Tee IF loss typ. less than 3.5 dB to 2 GHz
Variable Attenuator on IF 0 dB to NO signal

IMPORTANT NOTE: This Bias Tee box is designed for 10 MHz external reference source but you can also use internal 25 MHz TCXO, which is 0.2 ppm. Frequency error is max. 3 kHz.

IMPORTANT NOTE: Do NOT forget that the quality of the 10 MHz signal source has got final effect on the quality of the output signal. With added phase noise by PLL multiplying.

Internal duplexer (MK3) from LNB to RX

LNB bias tee duplexer 25MHz qro.cz hamparts.shop

Difference of IF signal: older and MK3 version

LNB bias tee spectrum comparison mk3 and older version qro.cz hamparts.shop

Options: Recommendations to buy

lnb bias tee box with recommendations by qro.cz hamparts.shop


- 10 MHz reference source locked to GPS signal
- RF output typ +5 dBm
- HW by BG7TBL, modification by OK2ZAW
- including GPS antenna and DC power cable
- 3.5 mm jack with GPS data out
- including coax cable with BNC and SMA (about 50 cm)
- please be patience, GPS lock could take long time at first time, also depends on the GPS satellite count etc.

2-way small splitter

- small splitter for 10 MHz reference signal
- splits 10 MHz signal to Bias Tee box and another your device (SDR, TRX etc.)
- low loss 3.5 dB

RTL-SDR receiver with 1ppm TCXO

- RTL-SDR USB receiver
- in metal box
- 1 ppm TCXO for better stability
- input SMA connector
- firmware already installed
- 8 bit, up to 2 MHz of spectrum
- compatible with HDSDR, SDR console etc.

Adalm Pluto

- SDR TRX up to 6 GHz

SMA-SMA cable

- SMA male & SMA male pigtail
- about 15 cm (total length 17 cm)

2-way splitter box with 10 MHz GPSDO

10 MHz GPSDO with 2-way splitter qro.cz hamparts.shop

Previous versions

   Manual for previous versions: manual


  • This is Low Noise Block (LNB) which works as Down Converter. You can use it for input frequency in range of 10 to 12 GHz. In amateur radio world you can build 10 GHz RX for QO-100 satellite, 10 GHz EME or tropo.

  • Device is designed only for Receiving.
  • Input of LNB is designed for 10 to 12,5 GHz. Original local oscillator (LO) is locked by 25 MHz reference signal and multiplied 390 - what means 9750 MHz. You can use different reference signals 25MHz +- to change LO frequency.

    IF = Input - LO [MHz]

  • For example IF = 432 MHz and Input = 10489 MHz

    LO = 10489 - 432
    LO = 10057 MHz
  • There is Variable Attenuator (ATT) trimmer. You can reduce signal strength as you need because the gain of LNB is high.
  • LNB with internal TCXO need some warm up time. Depends on the outside temperature, it is around 5 minutes. If you have small signal moving  it can be problem of antenna dish (LNB) vibration.

  • LNB with external TCXO has got stability around 1ppm stability. Signal can move by a few Hz in the short time period. LNB with external reference signal is locked to the external oscillator and stability is based on stability by this one multiplied by 390.
  • with voltage 11 to about 14 Volts the LNB has got Vertical polarisation, with Voltage over 18 V it is Horizontal.
  • We offer also LNB with POTY adapter. You can insert 22mm copper pipe as waveguide (WG) and part of YOUR POTY antenna.

  • 2,4 GHz POTY antenna is not included. Only 3D printed adapter.

  • Please, isolate WG pipe to 3D printed adapter against the water!
  • Do not forget, that dish antenna has got right FOCUS place. LNB holder is designed to mount LNB into the right place for maximal GAIN and also LOWER noise of the dish antenna. When you use POTY antenna, you have to place open part of the WG to the FOCUS. If you place LNB to the holder and POTY is in front of it, you degrade parameters of antenna a lot!

  • There is usually problem with the size of the POTY reflector and place in the original LNB holder of the dish antenna.

  • Example of the right way of the mounting: amsat forum.

Product details

Included in package

LNB and Bias Tee assembled and tested
POTY adapter (version with POTY)
DC plug - image
4pcs self adhesive feet pads - image

Box dimensions (mm) 58x50x24 mm - al box
Weight brutto (kg) 0.23 to 0.26 kg


Ing. Jan Šustr
ID 05476356, VAT CZ8407024780
Palachova 1777/7, 591 01 Žďár nad Sázavou, Czech republic, Europe

General instructions:

Please also read general instructions before handling the product.

European Union Declaration of Conformity

Manufacturer Ing. Jan Šustr (QRO.cz):

ID 05476356, VAT CZ8407024780
Palachova 1777/7, 591 01 Žďár nad Sázavou, Czech republic, Europe

declares that the assembled product:


is compatible with the relevant Union harmonisation legislation directives:
EMC Directive 2014/30/EU
ČSN EN 61000-6-3 ed. 2
ČSN EN 61000-6-1 ed. 2 (333432)

On behalf of Ing. Jan Šustr (QRO.cz)
Ing. Jan Šustr, CEO
25th December 2023

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