Posts by DL5CN

    Hallo,

    it is good to define phrases, why not. In addition, my comment is, in some cases the prenounciation could be clearer. Especially some weak signals are hard to copy even if the audio has low frequency parts only.
    No harm meant but some final amplifiers generate a lot of distortion and intermodulation products. It is easy to check the correct driving power and audio gain looking at one of the two webreceivers. At least the transponder itself is a flying spectrum analyzer and shows the own signal. Another question is how to hit the correct frequency if calling someone.
    As often repeated, for this reason the AMSAT always refers to duplex radios. No need to talk about the advantages of software defined stations. The daily signals show it.
    Don't mind me and I am far away from critisizing but a clear and linear SSB-Signal should be the goal of every amateur radio station.
    And guys, don't hesitate to mention it.

    73

    Andreas

    Hi Mark,

    all looks great. Here is a picture of my "radio", mounted closed to the LNB.

    It is a good weather unit. Don't care about the plastic cup which mechanical protects the helix. It was filled with beer once.



    Your PSU seems to be a little bit oversized :).

    Before portable operation you often have to adjust the dish, I recommend to use the transponders basic noise as an indicator.



    It can be seen cearly using 2 MHz bandwith. The software is SDR# with RTL-Stick V4. The rising of the noise while optimizing the dish is independent from any signal and frequency. Behind my dish, there is a little board to carry a small laptop. Moving the tripod and the dish and seeing the maximum noise at the display takes some seconds only. Especially outside of the motor home it seems to be useful using the RTL-Stick, a little battery with a current limiter, a bias tee and a laptop, independent from the radio and the Computer inside. I call it the "setup kit".

    In the last days I made some bad experiences with heavy wind. The radio acts as like a sail. More stability is needed.

    What is about a PTT-Circuit in your setup?

    Regards
    73
    Andreas

    Hi Mark,
    all the components you have are necessary. For portabel acitivies I recommend an outdoor unit very closed to the dish, probably fixed at the LNB carrier, as I do. That means for transmit the Pluto as the central part, CN0417, power amplifier. For receive the LNB and the Pluto are used. Both frequencies can be handled by the Pluto, no further mixing. A network cable goes into the motor home. The receiver is locked with the SDR console. If you expect different temperatures, a stabilized external 40 MHz-clock for the Pluto gives more fun, even when it is mounted outside. Leo Bodnar is my tip. No matter what type of dish you will use. The radiation pattern of the transmit antenna should match with the f/D of the dish. Mounting of a normal LNB with a feed horn behind the reflector plate of a helix cannot be the optimum. Some friends and I use slim line LNBs with a plastic lense instead of a Horn. The wave Guide with the lense can be placed in between the Helix. Both antennas are closed to the focus point. If you like, I send pictures. Another advantage is the easy change of transmit antenna type.
    73
    Andreas

    Hi,

    some additional ideas. I agree with Sandro fully. If you like to use LimeSDR or Pluto on the same band, with the same frequency, a good isolation of the receiver input is nessecary to avoid overdriving when amplified transmit power can reach the receiver. Probably a direct short cut at the boards input is required. With separate connectors for transmit and receive only an antenna relay is used. But it's isolation must be perfect. It is funny to play around with SDRs on VHF and UHF. But using it for QO-100 it is a complete different story.

    73
    Andreas

    ...das liegt daran, daß die meisten Journalisten nicht zuhören, wenn man mit Ihnen spricht und dann "irgendwas" schreiben.
    In den seltensten Fällen bekommt man einen Artikel vor dem Druck nochmal zu Gesicht, leider.
    Natürlich herrscht meistens Zeitdruck...

    Hallo,

    die Frage lauetet, ist die von der Pluto-Firmware erzeugte PTT immer noch 800ms verzögert?
    Ich hatte das mit dem Evariste mal besprochen, er hatte das bestätigt und auch Änderungen zugesagt, ich benutze mittlerweile POE-Adapter. Kann also sein, die Verzögerung ist jetzt geringer? Für SSB sind jedenfalls 800ms zu viel. Für den Pluto-Betrieb in einem Netzwerk
    wäre die vom Pluto selbst erzeugte PTT günstiger.

    Hat schon mal Jemand den Pluto-Spike angeschaut? Wie hoch ist der tatsächlich und wie lang?

    73

    Andreas

    Hallo,

    the Pluto boards are multilayer and have higher thermal capacity. With two solder irons and some low melting tin it will be possible. With hot air soldering a mask of aluminium foil around the oscillator is recommended to avoid blowing other nearby components away.

    73
    Andreas

    Hallo,

    it is not recommended to mount a better tcxo on the board again. It's temperature increases while transmitting. Use some small short pieces of wire stick all trough a nearby hole and let the TCXO flow below the board. The original blue box is not senseful because of thermal reasons also.


    This Pluto is mounted on a copper plated board, the above cover is Acryl with a small, slow running fan. The sensitive connectors are fixed and grounded with thin tin plated metal pieces which gives a better stability.

    73
    Andreas

    Hallo David,

    I remember a Chinese offer. Look for an OCXO at Aliexpress. It has a 10 Mc/s masterclock and other frequencies, especially 40 Mc/s can be selected by jumpers. It is cheaper than a GPS controlled Oscillator but works as expected. Some friends use it and their signals are stable.
    I am not sure if a portable equipment at different temperatures should have a Leo Bodnar better.
    73

    Andreas

    Hi Trevor,

    there are two possible ways to work in CW with the SDR-Console. Use a keyed tone generator instead of the microphone. Or use a separate CW-program and bring the audio signal via a virtual audio cable to the Console. In both cases you can define very narrow filters for transmit and receive. Monitoring the original signal from the tone generator or the cw program is recommended. Probably the vox function can be used to trigger the PTT.
    73
    Andreas

    Hallo,

    with the rev C/D Pluto no change in hardware is nessecary. But if one will use an external clock, a modification of the environmetal variable is requested. Use a short coax cable with a plug named "u.FL" to connect the external signal source.
    Login to Pluto with putty or similar tool. The name is "root" and PW "analog". Please Note, the PW is not visible while typing. After some other modifications (see CQ-DL download area) type

    # fw_setenv refclk_source external

    # pluto_reboot reset

    There is a paper in German about the Pluto changings, if interested, send me an email, callsign@t-online.de.

    73
    Andreas

    Hallo,

    I received an answer from Octagon, the Whispy-Series do not use a PLL and are obsolet. From my point of view such PLL-LNBs can be used even with a horn. If there is some waveguide after removing the horn to carry the transmit antenna, it will work. Probably there is some trouble with the original clamps so make a new one. Especially the the plug of the transmit cable collides with the clamp. Use SMA instead of N. If the PLL is not too far away from 9750 MHz leave the crystal untouched. Check the real frequency of the PSK-Beacon and tell the the difference to the Console . It will lock and be stable.

    73
    Andreas

    Hallo,
    I tested the scanning of 25 MHz with my LNBs. The shielding is different, some signals were rather low. Use a resonant antenna with the scanner, 5 turns and 150pF for example. The sensitivity goes up.
    73
    Andreas

    Hallo,

    good idea, thanks. Are there any further results, we can use to help the beginners?

    Octagon offers an interesting type, it's called "Whispy". It looks like, there is a plastic lense. Until now no answer to my email I wrote to OCTAGON.

    73
    Andreas

    Hallo,

    I was asked sometimes, which LNBs with PLL are available. The market seems to change quickly. That's why, I and others too would appreciate some informations about actual LNBs with PLL. From my point of view so called slim line or rocket types are easy to modify with an uplink transmit antenna. No matter if the antenna is a poty or Helix. If there is a 10 GHz waveguide, both types can be sticked together with a socket to the waveguide. Both antennas match with the focus point. The following link shows a picture.



    The sat-dealers don't know what is inside the LNBs. That's a pity. I would like to collect some infos about suitable LNBs to give it to others who are starting with a sat-station.

    Thanks
    73
    Andreas

    Hallo,

    ich glaube nicht, daß man alle Parameter, die am Zustandekommen eines Signalpegels über 80000 km beteiligt sind, so konstant halten kann, das Vergleiche von wenigen dB auf Unterschiede der Antennen schließen lassen. Wirklich interessant sind die
    Strahlungsdiagramme der Erregersysteme in beiden Ebenen und deren Öffnungswinkel bezogen auf den f/D-Faktor eines
    Spiegels also dessen Krümmung. Wie aus der Literatur bekannt, gibt es Empfehlungen für 10 dB Abfall am Spiegelrand gegenüber der Mitte. In der Praxis sind die Unterschiede zwischen Patches und Helixerregern eher unbedeutend. Die Montage eines LNB mit Rillenhorn hinter der Reflektorscheibe einer Helix erscheint bezüglich der Fokussierung und einer möglichen Abschattung allerdings nicht optimal. Bei einem Hohlleiter mit Kunststofflinse und aufgeschobener Patchantenne befinden sich beide Antennen deutlich besser im Fokus. Eine Abschattung tritt in diesem Fall gar nicht auf. Für die Funkpraxis via QO-100 sind diese theoretischen Betrachtungen fast bedeutungslos. Bei Beobachtung der Signale und deren Verständlichkeit sind Audio-Frequenzgang, Dynamik und Intermodulation von Endstufen m. E. nach die wichtigeren Eigenschaften.
    73
    Andreas

    Hallo Stephan,

    ich würde den Flansch/Ring auf dem LNB-Eingang (4) (der die Linse trägt) entfernen und, wenn möglich, ein neues Röhrchen passend auf den Hohlleiter stecken. Das neue Röhrchen hat dann vorn einen neuen, verdickten Haltering für die Linse und trägt dahinter auch die Patchantenne, siehe Foto.
    Eine Drehbank bzw. die Kenntnis eines Besitzers kann hilfreich sein. Die Länge des LNB-Hohlleiters wird nicht verändert.


    Hier hat das Messingröhrchen noch einen 3mm (plus Materialdicke) Absatz für den Abstand der beiden Bleche der Patchantenne. Der Vorteil dieser Lösung ist eine kompakte Anordnung für beide Antennen im Fokus. Auf Wunsch könnte man zum Testen die Patchantenne auch durch eine Helix mit einem gleichen Röhrchen in deren Reflektorscheibe ersetzen oder schnell tauschen. Die Hohlleiteröffnung samt Linse befinden sich dann inmitten der ersten Windungen der Helix. Verlöten lassen sich die Teile sehr gut mit einer Heißluftpistole. Die beiden Blechteile werden dabei mit 3mm Distanzstücken fxiert.

    Nach meiner Erfahrung funktionieren die Linsen der "rocket LNBs" am besten. Mit etwas Glück passt das 22mm Cu-Rohr Deiner Poty-Antenne auf den Hohlleiter bzw. den Adapter und kann mit etwas Nachhilfe passend gemacht werden. Die Durchmesser der Hohlleiter variieren aber oft.
    Daher gibt es die neuen Röhrchen.

    73
    Andreas

    Hallo,

    please have a look to this thread.


    Don't care about beacons. Try to see the noise floor from the ransponder above the LNB noise.
    Use an RTL-Stick V3 and SDR# to have a spectrum. It is good for finding the satellite and dish adjustment also. The possible SNR of user signals and the beacons are referred to the transponders own noise. That's why reports like 59 are useless.
    73
    Andreas

    Hi William,

    probably you are right if this is carefully discovered. It surprises me, that there are some motion detectors in small area. Because these sensors "see" each other and trigger each other. The poor oscillator design leads to lock effects between the LOs. Drifting by, funny effects can be seen. This happened on 5,8 and 24 GHz also. I remember a customer who wants to check a low angle range with some 24 GHz-sensors. The signals in the spectrum moved towards and locked each other, horrible. Sorry, but I have no idea what to do.

    I will ask some friends if there are more observations and solutions. As I told before, this will not happen in DL.

    73

    Andreas

    Hallo William,

    I don't know how the Dutch Regulations look like, in Germany the use of these sensors is not allowed. We have two ISM-Bands 5,8 and 24 GHz where 10 G-Motion Detectors can be used. 10 GHz-Systems from Asia are not legal. By the way, these oscillators are very unstable and noisy and drift with all parameters, temperature and supply voltage. The doppler effect based systems work with bad signals also.

    From my point of view interference in a narrow band system is hard to believe. These sensors have transmit power in the lower mW range. And the beam of a downlink dish is narrow too. Probably there are other noise sources in the envirement. Beside this, it is interesting to get more information. May be, for a test you can move the dish in different directions and locate the noise sources.
    73
    Andreas