Posts by DK1ML

    Bei der Änderung der TCXO Downconverter von GPS V 1 auf GPS V2 wird auch eine neue Firmware benötigt.

    Das heißt diese Downconverter müssen zum Flashen.


    ich habe im Source Code auf GitHub nur eine binary Version gefunden ( amsat-dl-sdc.production.hex ).

    Ist es tatsächlich nötig, den Downconverter umzuflashen?

    Habe eine Version aus der ersten Serie mit GPS V1 Modul und einen neues GPS V2 Modul extra, das ich benutzen will.

    73, Mike

    Hi Oliver,

    the 25 mhz are connected with a sma t-connector to the pluto and the lnb at the default singnal level (32mA). More singal level at the Pluto reference input gives a better spurious emission supression.

    To avoid reflections at the cable the lnb side should be terminated. I always use a combination of 10n, 150 ohm to ground and 10n to the xtal input of the lnb pll chip of the Octagon quad green lnb.

    This should work with 50 ohm and 75 ohm cables for the 25 mhz reference signal,

    For PTT generation i've used the old method where the data-0 line of the Pluto tx-chip goes via a small capacitor and a BAT41 schottky rectifier diode to the gate of a BS170 fet which is driving an optocoupler with his open drain.

    Today i would prefer the DATV firmware solution and just one LTV-354T optocoupler between the GPO0 and GPO1 pins.

    See: Pluto Mods: just 1 part PTT, DC-Mod, GPSDO Mod, Ethernet connect

    73, Mike

    Here are the ADALM-Pluto mods according to the latest knowledge, with ext. Ref. In (25 / 40MHz), PTT-Out and GND-Mod. so that Pluto doesn't crash anymore if you power any device nearby.

    The PTT output only requires an LTV-354T optocoupler which is soldered directly to the two pins GPO0 and GPO1 without a series resistor, no further transistors are required, but the switch-off functionality is still achieved when the Pluto is booting.

    To switch GPO-Pins for PTT the Pluto DATV Beta Image from 05.02.2020 from F5OEO is required (also for narrowband SSB operation).

    The heat sink set comes from the Raspberry PI 4.

    A GPSDO (e.g. Leo Bodnar) or a TCXO or OCXO can be connected to the external reference input.

    You can find out how to reprogram the frequency from 40MHZ to 25MHz on my page.

    At 25Mhz the LNB can be synchronized with the same GPSDO as the Pluto, so the beacon stabilization of the SDR console is obsolete.

    The 2dBm (1.6mW) from the Pluto device can be easily increased by 33dB with the PA according to DB4UM, so you can drive a 20W SG-Lab PA with 500mW from this small unit.

    I've used the DB4UM (driver) amp directly for test purposes with about 3.5W output after 10m low-loss cable on a 65mm dish with POTY dual patch feed. The amp connected between Pluto and POTY is able to generate a readable SSB signal on the satellite with around 70% of the beacon level.

    To connect your Pluto by ethernet the ideal adapter is the ICY BOX IB-AC510 where no extra OTG adapter is needed. Just plug the micro USB plug to the left connector at the Pluto and supply 5V to right-hand USB connector. The settings are managed by updating the config.txt file on the PlutoSDR mass storage device.

    By default DHCP is activated, but you can assign a static ip at this tag:


    ipaddr_eth = # <-- assigned fixed ip

    netmask_eth =

    After this modification you have to eject the Pluto drive in Windows to activate the new configuration.

    73, Mike DK1ML

    Hallo lieber Moderator,

    leider hat EBAY offensichtlich etwas gegen die Firma HiDes, deswegen hat man weder in DL noch bei Erfolg bei der Suche nach dem Schlagwort "BU-500".

    Ich habe selber schon etliche Upconverter verschiedener Hersteller getestet und auch schon ein paar BU-500 verbaut. Der BU-500 gehört wirklich zu den besten Optionen, ist aber leider durch den EBAY Boykott nur sehr mäßig am QO-100 Markt vertreten.

    Die Lieferung erfolgt innerhalb weniger Tage aus OE und nicht aus Taiwan.

    Ein beiliegendes Messprotokoll bestätigt die Daten jedes einzelnen Konverters.

    Ich fände es also recht hilfreich, wenn man den Link zu EBAY posten dürfte, oder zumindest eine Artikelnummer zur eigenen Suche.

    73, Mike


    PS: Ich bekomme kein Geld von HiDes für den Kommentar und bin auch kein Händler :-)

    So the solution is to recompile GQRX with start function enabled by default.

    I have my own WEB-SDR from Pieter-Tjerk but this is no option at all :-)

    Thank you for the hints.

    Is it possible to start GQRX automatically without any user intention if there is no keyboard, mouse, touchscreen or touchpad?

    Just like the Elecraft PX3 spectrum display.

    There are two tasks to manage, at first GQRX has to be started by shell and afterwards the start button/function must be activated.

    Any ideas how to do this will be highly appreciated :-)

    73, Mike


    is there any autostart option for GQRX?

    I want to use the PI4B just as a spectrum monitor without any user action (OV-Heim).

    The beacon stabilisation is not neccessary (GPSDO).

    What is the default root password for the image for SSH/SU?

    73, Mike

    Hi Thomas,

    I am talking about the center beacon at 10.489.750,00 as shown on the picture.

    This is the center frequency of the SDR range at 0 (zero) hertz.

    All SDR receivers have this "blind" frequency in the middle of the reception range, sometimes with a phantom signal if the balance is not accurate or if there is some 50hz hum.

    I have set the range of my online WEB SDR 5khz left of an important signal.

    But more important to me is that you confirmed the same frequency error at 10489750.08

    73, Mike


    after change of the bandplan the UK WEB-Sdr is -80Hz off frequency.

    By the way, it is not very smart to set the center frequency of the Sdr to the beacon frequency because of the zero point at the middle, what is shown as a black bar.

    It will be nice if somebody can inform the responsible old man :-)

    73, Mike

    Hi Frank,

    I think, that a used Windows Notebook for less than 100 EUR with the SDR-Console is more powerful and cheaper than a 50 EUR Raspberry Pi with touch display that alone will cost around 100 EUR.

    That is the reason for the lack of demand for your good software,

    73, Mike

    Hi Daniel,

    a simple single wire cable from the PTT pin of the transceiver to the up-converter will be fine.

    Another option is that you use a bias tee to provide the PTT signal via the coax cable. This kind of power injector is used for the lnb power too. Just insert another one at the if-output of your rig which is connected to the PTT line.

    73, Mike

    Hi @ll,

    there are some stations with massive audio distortions using the Kuhne Phase-4 up converter 2424 B.

    It is mandatory to connect the PTT line to your transceiver!

    This is NOT a plug an play solution, you have to put out your soldering iron ;)

    The Kuhne equipment is always a good choice, but you have to use it in a correct way.


    Der Kuhne Phase-4 Up-Converter muss unbedingt an die PTT Leitung des Transceivers angeschlossen werden! Wenn das nicht geschieht, hört man massive Störungen im Audio Signal, besonders in den "leisen Passagen", ähnlich einer falschen Bias Einstellung bei Kurzwelle.

    Bitte liebe Steckdosenamateure, holt den Lötkolben aus der Schublade ;)

    Kuhne Equipment ist eine gute Wahl, man muss allerdings die Geräte auch richtig anschliessen.

    73, Mike


    Why you will use different equipment for transmit and receive, thats like in the 50's with two separate vfo's :-)

    For DATV transmission you will need a 300w (real linear) pa and a dish >2m.

    The portable station in action @Mykonos Island :-)

    Easy 5 min. set up.

    46.6 deg. elevation for Greece.

    The ash tray special mount :-)

    25 w for beacon level with the 40 cm dish.

    Ready to go for a QSO.

    73, Mike

    PS. I use 3m Aircell-7 with N and SMA connector as the TX cable (loss 1.2 dB).