Posts by DL5CN

    Hi,

    my recommendation are chinese boards with SZA2044 or SZM 2166 Chips from Sirenza. These boards work well between the Pluto and the SG-LAB Amplifier. All this is available on ebay. The french offers seem to expensive to me.
    In addition a PC, a USB to Ethernet Converter and Power over Ethernet Adapters are useful. Please use the search function in the forum.
    All this was discussed and written down so many times.
    It would be nice to know your name.
    73
    Andreas

    Hi,
    yet another wish. If you talk about amplifers and power don't forget the intermodulation distortion. Single tone values are useless.

    The Console in combination with Pluto gives an excellent two tone signal.

    The screen shot is an AMSAT-PA (with preamp) with good linearity. Please note, two carriers with 30 dBm give 36 dBm, that are 4 Watts.

    With the preamp, the amplifier does not need any driver and can be used direct after the Pluto.
    The intermodlation distortion products can be related to the carrier level or to the PEP-level, which is 6 db more. This looks much better in the datasheets.



    Not only a "dB world" but a linear world too :-).

    73
    Andreas

    Hi Guys,
    which unit do you use for return loss? What shoes your network analyzer for S21?

    With modern concepts like network and spectrum analyzers and SDR-Technology we have to get used to logarithmic systems. There is a little software from Rohde & Schwarz for Android and PCs also. It is called "dBm Calculator". You can transform linear and logarithmic units to each other. It helps, to get familiar with all this.

    73
    Andreas

    Oh Boys,

    did you ever heard, with logarithmic values, gains and attenuations can be added easily instead of multiplying and dividing. We should follow the professionals.

    Look forward, please.

    73
    Andreas

    Hallo Josh,

    ok, all is fine. And if you take care, the radio function ist satisfied.
    It is a pity that ICOM didn't go one step further to bring the 705 to duplex operation.
    A simple approach to a portable Radio is a Pluto followed by the AMSAT-6W-Amp.



    The rest is power supply and - if wanted - a GPS-RX. The rig is mounted with two clamps closed to the LNB holder.


    The only Connection is a Ethernet cable. And Power. 12V from a battery or from mains. With a short wiring to the Helix, 4 linear watts out of the amp are enough. As you see in the first picture with my dirty setup it can be done smaller still. A WEBSDR requires a PC. This is good to operate a Pluto too. In the field it is nessecary to have a sunshield. This is a disadvantage of modern displays not working in a bright environment.

    73
    Andreas

    ...."there is no radio that can work duplex"....

    Hey Guys, don't know if I should laugh or cry.
    Is it nessecary to talk about the Pluto again and again really? From my point of view full duplex means listening exact on the same frequency. One can see and hear stations transmitting very closed to or direct on used channels. Or finding their own transmit frequencies, scratching across the full transponder with full power. This is modern technique, horrible. I am sure, they have no spectrum displays and no duplex radios. I don't like to repeat all the other advantages of SDRs.
    But I like to repeat offering help and support if needed and or wanted. Radio Hams were always seen as open to future technologies. SDR is not future is present. I don't see any reason not to use it.

    Give you a kick and start....it is easy.

    73
    Andreas

    Hi George,

    I'll try to post a picture.



    The Controller on the board is an ATMEL TINY 45. There are Boards with a - well known - C340 Chip. There were not recognized by the Console. I don't know, why Simon uses so hard restrictions.
    I use a PTT-Chain, starting with a button (USB to TTL Converter) which pulls a status input to GND. This triggers the Console and the above shown relay. The PTT-Signal is send to the amplifier with two Power-Over-Ethernet-Adapters in combination with the ethernet cable. With this configuration, the Console itself can control PTT when transmit call sign or voice keyer.
    73
    Andreas

    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