Posts by DL5CN

    Hi Guys,

    use a modern SDR-Concept and all the trouble is gone. Full duplex, easy tuning, synchronize with the PSK_Beacon, only one oscillator for tx-stability, tx-equalizer, envelope compression, spectrum display, two tone signal for linearity tests, what else do we need? Don't be afraid in front of digital technologies. You are not alone. Don't hesitate to use it. If nessecary, you get help. The terminal program from G4ELI is free of charge. From my point of view this is very remarkable.
    Have fun.
    73
    Andreas

    Hallo Ernst,

    at least I agree with you :-). The Console levels do not show the real SNR but are rather comparable under the discussed circumstances. May be, Simon will find the motivation to implement another DSP-routines one day. Probably just like PowerSDR. It's level measurement works perfect.
    In summary we are more than satisfied to have a program like the Console. All properties together give excellent satellite operation possibilities. Not to forget the Pluto. Who watched - as i did - over the last two years the deveplopment of this program has to bring a highly estimation to Simon.

    By the way, a friend, DL4JAL, desinged an USB-Control-Unit with Audio in- and output, PTT-Switch and a generator for CW. More details can be found on his website. All the functions are summarized to one USB-Port, controlled by a PIC.

    73
    Andreas

    Hallo Ernst,

    thanks for your informations. Unfortunately the Console ist not the best instruments to do such tests. To compare SNRs of a specific station between stations at different locations, there are some more parameters which has to be kept comparable. The zoom value for example has an enormous influence on the level meter. When I do the test, you described, I find 35 dB peak of the idle carrier of the CW beacon. But we know, this is much to much. To get reliable results other level meters with other instruments have to be used.
    The Console Level Meter is good for optimizing the own dish or LNB position. From former threads we know, the transponder signals will not override 20 dB SNR, also with larger dishes. If you can see the transponder noise floor clearly, your receiving system is ok. There is nothing left to do. SNRs of the stations you receive, depends on their transmit power only.
    From my unimportant point of view, when turning a dish to the sat, the increase of the noise floor is a valid criteria to optimize position and checking the own receiver. And, this absolutely independent from other parameters. We talk about 3 KHz bandwith.
    Please don't mind me, discussing it a bit controversly.

    73
    Andreas

    Hallo Lucio,
    thanks for the picture but this is not what I expect. I would like to see the filter curve (may be highlighted) in the display.

    Here you see a part of a spectrum. The filter curve is gray.


    In the IC705 spectrum there is just a white line, this is the carrier frequency.

    73
    Andreas

    Hallo,

    is there anyone outside who knows if the IC705 can show the filter curve in the Display. Just like the Console does. And many other SDRs do also. If not, this will prevent me to substitute the FT817. As far as I know, Icom doesn't like to show the filters in their radios. It's hard to understand. Probably an update will bring it. I do not ask, if a two tone signal is avalaible. Some lines code more and it is done.
    Have fun, beside my questions

    73
    Andreas

    Hallo,

    here is the simplest radio ever, take a Pluto and the AMSAT-PA with integrated Preamplifier only. Don't worry, it's a quick and dirty test setup. All is running with 12V only a 5V switching regulator feeds the Pluto. The current limiter is for fearful oms.


    Mount this closed to a dish, connect it to the PC via Ethernet. The linear 4 Watt from the amplifier are enough. With careful adjusting the equalizer and compression you get a pretty nice signal. The efficiency of the amplfier is remarkably good. The current consumption of the radio does not exceed 2,5 Amps at 12V. That means, it's good for portable purposes also.
    Have fun and a nice Whitsuntide to everyone.

    73
    Andreas

    Hi Chris,

    thanks for introduction.

    If you decide to change the oscillator, don't put it back to the original pads. It is much better to have a thermal isolation. I used a very small board just to solder four wires to the original place. There is a whole, closed to the solder pads. Stick the wires though to have the oscillator free hanging below the main print. Temperature influence of the main board is reduced. A little fan above the heat sources can be helpful too. Otherwise a "Leo" is much better of course.

    For removing the original oscillator use two irons and some more tin around the chip. The lead free tin is horrible. Turn the irons to more heat and you will remove the Chip within seconds.

    73
    Andreas

    Hallo,

    it would be nice to know your name.
    If the receiver is locked to the PSK-Beacon all is fine for receiving.
    The only oscillator which has influence to the transmit frequency is the 40mc clock on the Pluto board. While transmitting the board warms up and the oscillator starts drifting. Either you change it to a better one or use Leo Bodnar GPSDO. A possible shift should be changed with XIT-function of the Console. Don't use any calibration.
    When using the 500HZ-tone of the Console, you can compare the transmit and the received frequency to achive beating while adjusting XIT.
    Have fun.
    73
    Andreas

    Hallo,

    is there anyone who measured an amplifier with the SZM2166? The gain is lower than expected. The datasheet shows three stages compared to the SZA244.
    I would like to see some S21-Measurement and if possible an intermodulation spectrum.
    Thanks
    73
    Andreas

    Hallo 2E0ILY,

    the Plutos input has a wide frequency range. The LNB receives unwanted signals which will be mixed with Plutos LO-harmonics into the intermediate frequency. Use a filter at 739 MHz. There are low pass filters available for this frequency too. They block signals from strong base station transmitters into TV-systems above 800 Mhz.
    73
    Andreas

    Hi Guys,

    there is a definitve difference between connecting the Pluto via DHCP or direct to a PC. Search for the specific posts, it is all written in this forum already.
    DHCP means there is no change nessecary at all, just connect the Pluto to a router. We do not talk about aministration in a home network, there are fixed IPs possible of course.
    My recommendation is a direct Ethernet-connection to a PC.

    73
    Andreas

    Hallo,

    is there any information about the first MMIC in the SG-Lab-PA V3? An om in the neighbourhood has some trouble and I'll try to help.
    A type or a link to a datasheet is appreciated.
    Thanks
    73
    Andreas

    Hallo Mike,
    thanks for translating. I wasn't sure about the language to answer. Obviously you do German quite well, respect.
    You are right, sometimes the RIT is helpful. I changed the Plutos TCXO to a better one. And it is okay at room temperature. The LNB is modified to a 25 MHz-TCXO also. This gives more aaccuracy. The goal is to feed both units with 25 Mhz out of a GPSDO to get independent from the beacon. I know about the doppler shift, it is fascinating.
    Happy Easter to everybody
    73
    Andreas

    Hallo Ömer,
    das ist leider nicht so, die Sendefrequenz wird von der Empfangsregelung NICHT beeinflußt. Für die Sendefrquenz ist der TCXO auf dem Pluto zuständig. Ein eventueller Offset zum Empfang sollte NUR mit der XIT der Console ausgeglichen werden. Verwendet man statt dem TCXO einen GPSDO kann die XIT auf Null bleiben.
    73
    Andreas

    Hallo,

    the above comment sounds strange a bit. If I want to buy a specific revision, I should get one. Otherwise it goes back. Mouser or digikey can sell any revision to customers who don't care.
    Who placed the youngest order? Which version was delivered? Are there older versions in stock? By the way, there are different releases of CN0417 too. Revision C contains a temperature switch. It can be used as a PTT-circuit. 600mA continous current consumption are unacceptable. May be, a chinese version of an amplifier with a SIRENZA-MMIC SZA2044 is doing the same job. Less current, a bit more gain and a standby pin also.
    Happy Easter

    73
    Andreas

    Hallo,

    an overcurrent protection is well suitable for any kind of experiments. PTCs do not protect in case of just overriding a specific limit. They get hot but don't switch off. This is good for hard short cuts only, assuming the power supply can deliver enough current.
    Playing around with sophisticated electronics a switch can save live. When developing circuits, measuring and soldering it is nessecary to disconnect the feed voltage even with every change. Probably a fast switch beside the test object can help.

    73
    Andreas

    Hallo,

    88 Dollars for a little box and some cheap components? Is it hamlike still?
    It is very easy to assemble a bias feed, a choke and a capacitor. If an attenuator is necessary use a cheap one from 75 Ohm tv cable systems. Max. attenuation is 20 dB. In many cases it is possible to operate LNBs with less then 12V. This reduces dissipation and increases stability.
    As I remember, any kind of advertisement is unwanted here.

    By the way, this is a little current protection circuit. When experimenting and feeding LNBs with supply voltage and connect and disconnect the F-plugs shortcuts can happen. To avoid smoke, the circuit switches of, if a specific current is reached. R3 opens Q1and the FF is set. Q gets high and the FET is off. An additinal feature is, the LNB can be switched on and off to check the increase of the noise. D2 limits output spikes.

    Happy Easter

    73
    Andreas