Posts by DL5CN

    Minimize the Mini-System - Searching the Satellite

    Hallo,

    another idea to reduce. The combination of LNB with horn and a scanner was used to check a location because of trees and buildings which prevent receiving.

    The CW-Beacon helps to find a gap.

    73s
    Andreas

    Hallo,
    the modification works.

    First grafic shows the 1W PA unmodified and another wide band amp which is ok. S21 is measured against 19 dB attenuators.


    The second grafic shows the modified 1W PA. The gain maximum is shifted to S-Band.

    Don't be confused about the ripple. It is amateur equipment. :)

    73s
    Andreas

    Hallo,

    very interesting to me also. I own this board and can confirm no gain at 2,4 GHz. Maximum is about 1 GHz. The modification is similar to the datasheet. So, thanks to DK5DN for publishing, I will try it and report. Last question, what is about the feed choke.

    I think it is unmodified yet?

    73s
    Andreas

    Hallo,

    the problem is fixed with a friends help. Thanks to him.
    Pluto works together with a standalone PC without a router.
    This is the only change in the config. txt.


    [USB_ETHERNET]

    ipaddr_eth = 192.168.1.205

    netmask_eth = 255.255.255.0


    The IP is just an example. Assign a fixed IP in the host with the same subdomain and subnetmask.

    Additional type Pluto's IP in the standard gateway mask.

    73s
    Andreas

    Hallo,

    who can tell me, how to configure the config.txt of the Adalm Pluto for direct IP-Connection. It works well with DHCP. Adding the IP, assinged from the router, to the SDR Console, all is fine. But I don't get it running with direct Ethernet-Connection. There are more than one IP-Definitions in the "config.txt". Editing the config and eject the Pluto-drive to save the config is ok. No matter, if the host is assinged to the same subdomain.

    By the way, I found the board was very sensitive against any kind of em-interference. Mounting it on PCB and grounding the connectors to ground, it seems like the effect is reduced. The fan is connected to D3, closed to the power input. 73s
    Andreas

    Hallo,
    unfortunately I do not own any commercial S-band equipment, even no specanalyzer. Lime SDR Mini can do double tones, the transponder itself shows the linearity of the signal. My goal is to drive the focus to linearity and gain, two important parameters, especially in combination with SDRs which give about 0 dBm power. One pa-stage has less gain. May be it is useful to enlarge an amplifier board with an optional driver.

    73s

    Andreas

    Hallo,

    sorry, I have no idea where the horn comes from. It is just out of the junkbox, like the tripod also. I am not sure if the quarterwave structure of the grooves in the horn matches to x-band. But the radiation pattern seems to be ok.
    Finally it is nothing else but a little joke....and even the challenge.... ;)

    73s
    Andreas

    The Challenge
    Here is my minimalistic system. It is an Octagon Single combined with 12cm Horn. The LNB is not modified. For the first quick test, the supply is a battery still. StepUp follows. The audio is clear with good short term stability. Of course there is a thermal drift.


    With 500Hz bandwith the CW-Beacon is up to 20 dB above noise. There is much qsb. Before further tests, it is not clear if the fresnel lense gives more gain.



    73s
    Andreas

    Hallo,
    i wil pick up the challenge to assemble a minimalistic system. The Octagons have a 6V internal regulator. We need 7,5 Supply for the LNB. The "USB powered injector" is a little step up ? More supply to the LNB means more dissipation and is unnecessary.
    73s
    Andreas

    Hallo,

    here is another example. It is an Octagon Twin. The feed horn of the LNB is removed. The coupling between the LNB and the 22mm copper tube is done with a brass disc. Meanwhile I am not sure if the thermal coupling with all the copper and the LNB is a good idea really? It is all soldered with hot air. The S-Band antenna seems to work, 2 Watts and a 80cm dish give a satisfied transponder response.

    My home made return loss brigde has to be improved before showing a pattern.

    73s
    Andreas, DL5CN


    Hi, yes it does.
    It must be an USB3.0 Hub. The hub is feeded with a 5V switching regulator. It is connected with a small sound card and the relay also. The Lime board is mounted upside down with some thermal pads. The actual version of SDR Console works in duplex mode. I use a dual feed with a 1,3 m offset dish. Beside the LNB no further components are needed. The "Radio" operates with 12V.
    73s
    Andreas, DL5CN

    Hi Achim,
    thanks for the hint. SDR-Console supports an USB-Relay meanwhile, so switching the supply is simple but not very elegant. The LimeSDR Mini gives approx. 0 dBm, the total current to the amp. is about 2 Amps.
    At present, I use all the equipment in a portable way, the dissipation is limited. But for longer standby a switch off of the idle current is useful. The picture shows the "Radio" below the laptop.

    73s
    Andreas, DL5CN

    Hallo,
    I use this amplifier. It works well together with a LimeSDR Mini. I would like to know, if there is any solution for a standby mode.
    The idle current generates some dissipation. It would be nice to avoid this.
    Thanks
    73
    Andreas, DL5CN