Posts by SV1BDS


    Using LimeSDR-USB a 3.7 GNURadio flowchart is created for displaying MER and exact frequency.

    QPSK and 1500,1000,500,333,250,125 kS are supported.

    Frequency step is fixed at 250 KHz, according to band plan.

    External clock for Lime is not yet supported in flowchart.

    Python code is attached (you have to remove the .txt).


    For portable operation a 13.8V power bank using 4*2 surplus matched 18650 is used.


    13.8V, 3A max (limited) output.

    5 hours @ 500 mA discharge time.

    V&A meters @ battery.

    Charging current 1.5 A (750 mA for each 18650)

    Charging input voltage 4-30V.

    LEDs charging indication

    Anderson 30A output connector.

    S4 Lithium protection unit.

    Teflon cables.

    Electronic 3A fuse at charging input.

    Dimensions : 150*110*50 mm.

    Weight : 820 gr

    Update: a non plastic material, heat resistant, replace the white plastic 18650 insulation separator .

    2.320 GHz W1GHZ transverter


    Frequency range : 2320-2322 MHz

    IF : 144-146 MHz

    Power input : 1 Watt

    PTT : external input

    Frequency reference : 10 MHz external

    Receiving sensitivity : -125 dBm / 12 dB SNR

    Power output : 1 Watt (CN0417)

    SWR protection : full (circulator)

    Tx image rejection : -40 dB

    Harmonics rejection : -50 dB

    Power voltage : 9-13.8 V

    Rx current : 150 mA (@12V)

    Tx current : 1A (@12V)

    Dimensions : 250*160*55 mm


    A OCXO based 10 MHz oscillator is built around the OSC5A2B02. A 7805 provide 5V to OCXO and to a 4.096 V precision regulator for the trimmer that tunes the OCXO. A 74LS04 buffers the output and drives one more inverter giving TTL output and two pairs of inverters drive two LPF that produce two +20 dBm sine outputs with harmonics 40 dB lower.

    The result is a signal that has a +-15 Hz jitter at 10 GHz. It is close to final frequency after about 5 min.


    For testing purposes the received beacon is TCP streamed to the QTH Fiber 100/100 and is received via VLC to my mobile phone.

    And one proposal to implement : why you do not add MER?

    It is relative 'easy' to implement.


    This 35 dBm (3W) 19 dB power amplifier for 2.5-2.7 GHz works down to 2.4 GHz. The problem was that it works from -12V to -28V. It was modified for +15V operation. A DIP MC34063 was used to invert the +15V to about -8V. As the space was limited and even the Chinese PCBs do not fit, a spider construction was successfully used. Some online MC34063 calculators was used.


    A modification is applied to a modified twin Octagon LNB with 25 MHz insertion using a 2.2 uH & 18 pF as OZ2OE proposed, that replace meander with a 5.6 uH (have more that 75*10 ohm resistance at 25 MHz). The existing 10 ohm in series with meander is replaced with a 0805 one in order to solder the 5.6 uH.

    The result is that in NB similar performance exist as before. But in WB the MER for beacon is improved about 0.3 to 0.4 approaching the LNBs performance with XTALs MER but with GPSDO accuracy and stability. Replacing 25 MHz source with lower noise OCXO as mentioned before , a very small increase must occurs, must be about 0.1 (may be ...) .

    It must mentioned with this modification the required 25 MHz signal in order to lock the LNBs PLL, is a lot of dB less, but for optimum performance the previous level is required (in my case about 13-15 dBm).

    This idea is generated while discussing with SV1UI about the loss of 25 MHz signal due the 950 MHz HPF that exists in LNBs output.

    Also the output signal of some LNBs is measured from 350 MHz to 850 MHz. As the results is not very accurate a typical performance is a few dB less signal at 740 MHz and about 10-15 dB at 430 MHz. The attached screen is from an unmodified twin green Octagon LNB.

    Hi, it looks correct. The SPF5189 can reach this output power at maximum. Consider a few dBm less. The reason for not using a SPF5189 at output is that it has the same gain but cannot produce the required power. Maybe you need to lower the output of SDR, add BPF between amplifiers (if you see self oscillations-if you can see them...) Or add an SPF5189 between coax and final amplifier. Also I have noticed increased attenuation slowly over the time at 2.4 GHz.