Posts by DK1ML

    Hi Peter,

    i am always operating my transceivers in simplex mode, no matter of the capability of crossband operation. There is no difference to a separate setup for rx/tx, because i have an option to monitor the feedback from the satellite at any time.

    There are provisions for a Pluto, TCXO RTL-Stick or just another analog receiver.

    We are in 2020 and not in 1950, so it should be no problem for a licensed ham to keep rx and tx on track without separate radios or the usage of a pc.

    It depends on the quality of your over all setup and a good working stabilisation.

    Which setup for (real) portable use do you prefer?

    The IC-9700 is not a realy good choice for field operation.

    What is the alternative? Two unsynchronised FT-817/818 ?

    Or IC-705 twins - my choice.

    The Adalm-Pluto is not an option either, because it needs a pc/laptop.

    If the the equipment is designed in a perfect way, the signals are as good as from a shortwave radio.

    Just turn the dial to the received station, hit the ptt and be transceive, thats the goal :)

    Have a nice weekend.

    73, Mike

    Hey Thomas,

    after more than 1 year QO-100 operation and 1.000 QSOs i am familiar with all kinds of playing the SHF-game :) The own voice is still annoying to me !

    It is always the operator if something goes wrong with the signal quality, sometimes the equipment is another obstacle. As a HiFi-SSB fan, the low bandwith of vintage transceivers is also a reason for an upgrade.

    The really bad operators are turning the vfo knob while transmitting, to find the actual TX frequency. This is as bad as an offset, that the most not GPS controlled stations have with their QSO partner.

    But this all is not an issue of the new IC-705 if the right old man is sitting behind it.

    Have a nice weekend.

    73, Mike


    Hey Mike,

    the radio is really cheap for all the features that it have, including battery operation from 160m....70cm.

    If they will built in another complete receiver like in the IC-9700, this will take space and about 500-800 EUR extra.

    I have never used the satellite mode of the 9700, it is annoying to listen to the own voice with a latency of 200-300ms.

    A better choice is, to have always running a spectrum analyzer in parallel like me, or to watch the own signal with one of the WEB-SDR's or by the SDR Console.

    For me is the IC-705 perfect for the next holidays with a Juma 1000 PA and my 45W 2.4/10GHz GPSDO Transverter, where a Pluto is included as well.

    The worse signals on the satellite are resulting in worse operators, or old equipment, not in a missing duplex mode :)

    73, Mike

    Hi Peter,

    it is just a simplex transceiver, but i always use the same QRG stabilized by GPS for TX and RX, so there is no need for a satellite mode.

    The waterfall display for transmission check can be achieved by the WEB-SDR or with a tablet with the SDR-Console / RTL-Stick which i have built in at my transverter.

    73, Mike


    100 hz or 130 hz is definetly too much, i am operating a web sdr (from Pieter-Tjerk@Twente) as well.

    The BATC uses GPSDO locked AirSpy SDRs.

    If the operator sets the wrong offset in the linux config, than the values are not exact.

    My own local station is all the time 100% on frequency with 2 Leo Bodnars.

    Just the gravitation doppler shifts +/- 30Hz, which can be averaged.

    73, Mike

    Hi Jens,

    the internal LED is a flat 3mm type - not smd.

    Just unsolder one leg and solder a 2 wire cable to the original pins of the LED at the PCB.

    The cable will fit through the hole if you bend the LED by 90 degrees.

    At the other end of the cable a new LED can be mounted with correct polarity.

    73, Mike

    Hi Mike,

    mostly the external level for the TX/RX chip is too low, which results in spurious emissions.

    You can put almost any rectangle (not sine!) signal via the on board 18pF capacitor C123 to the clock pin, this is attenuated enough. If you use a reference clock below 25 MHz it is strongly recommended to use a second 18pF capacitor in parallel.

    73, Mike

    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