IS0GRB Winlink Server on QO-100 (Dial 10489635.0 USB)

  • Dear Roberto,

    Congratulations for your winlink server.

    It's working very good.

    Tks also EA5HVK to support...

    Setup here:

    90cm dish, Poty Feeder, ca 4W edup eb003.

    Upconverter BU-500 (No external reference), and Kenwood TS2000.

    RX via SDR Console 3.0.10

    Vara Sat 3.0.2

    Winlink Express

    Find attached pictures...

    TNX AND 73,

    DE PR8KW GI77ul

    Gustavo Schwartz

  • I am very happy with the results that are being achieved, having the possibility to send and receive e-mails via satellite is an incredible opportunity, especially for dx speditions, in faraway places or by boat.

    Thank you very much for the tests done Gustavo, you are very kind

    Today I have added a more powerful server and minimized RX buffering by direct high-speed listening on my websdr gps locked, eliminating additional programs and slow SDR interfaces.

    All this has allowed a remarkable increase in performance.


    Roberto IS0GRB

  • Test with Vara Sat 3.0.4.

    send 16484bytes in 03:30.

    4686 bytes/minute.




    Below today Vara Sat LOG.


    24/07/2019 22:47:29 Connecting to IS0GRB... 1/2

    24/07/2019 22:47:36 Connecting to IS0GRB... 2/2

    24/07/2019 22:47:45 Connected to IS0GRB

    24/07/2019 23:01:09 QRT Received

    24/07/2019 23:01:09 Disconnected TX: 98 Bytes (Max: 362 bps) RX: 25040 Bytes (Max: 587 bps) Session Time: 13:24


    24/07/2019 23:03:32 Connecting to IS0GRB... 1/2

    24/07/2019 23:03:42 Connected to IS0GRB

    24/07/2019 23:07:50 Disconnected TX: 16608 Bytes (Max: 1978 bps) RX: 126 Bytes (Max: 272 bps) Session Time: 04:08

  • This evening after the excellent results of email transfer with large attachments obtained with Gustavo PR8KW from Brazil with system without GPS and light drift in transmission up to 100Hz after about 10 minutes, another excellent result with Oscar DJ0MY with station equipped with GPS, that has transferred 10k of attached in 2 minutes and with a constant speed of 2000bps with the new 3.0.4 VARA SAT modem registered.

    These are the screenshots reported from Oscar DJ0MY:

    All these tests are of great importance and give the idea of how the system can work even with a simple configuration.

    With the new modem VARA SAT 3.0.4 of Jose EA5HVK and with AFC of +/- 150Hz max, you can manage quite well also transverters drifts not equipped with GPS reference and this is very important, even if with a slight decrease of performance.

    Today also Michael DG0OPK has tested the system even if with low speeds because the VARA SAT modem was not registered and therefore without enabling high speeds


    After several tests these are the suggested configurations to achieve good connection results:

    - Install always the last version of the modem VARA:

    - Install always the last version of the Winlink Express program:

    - Adjust the audio level of the analog receiver or the SDR so that the VU meter of the VARA SAT modem is in the first green segment after the initial yellow segment, around -30dB of signal, to avoid false decoding

    - Adjust the receiver filter, if possible, to 2.8kHz or better to 3.1kHz, as with high speeds the VARA modem requires more bandwidth

    - Equip the LNB and the converter / transverter with a GPS reference (not essential even if recommended)

    - Before transmitting regulate, if internet connection is available, your own transmission frequency with a precise reference, for example a WebSDR, you can connect, for example, to my WebSDR ( with GPS reference, set 10489635 USB, zoom in and send your VARA SAT modem in PTT from the Settings > Soundcard menu by pressing on the TUNE button.
    Verify that the transmission frequency is exactly 10489636.500 (1500 Hz tone), otherwise adjust the VFO to center it.
    This initial operation is very important and guarantees a secure connection for those who are not equipped with GPS, considering however a succession slip which the VARA SAT modem AFC can manage, but require internet connection and in places not covered this is not possible.

    - If you use the Audio Virtual Cab driver, set the frequency of 44.100kHz and not above to the properties of the playback and recording device.

    -It is absolutely important to request the registration key to Jose EA5HVK satellite tests in order to enable high speeds with the VARA SAT modem and contribute to the tests that Jose EA5HVK needs to further improve the performance of the VARA modem via QO-100.

    -Avoid, if possible, to change the transmission frequency during a connection session, even if you notice the AFC vary, as the transfer performance decreases due to the failure of the 2 modems to synchronize.

    The 2 modems automatically manage the AFC in RX and until the drift does not exceed 100Hz and ends in the yellow zone, leave the transmission frequency stopped

    - Check the modulation level and avoid distorted modulations, possibly reduce the output power level of the transverter or the amplifier.


    At the moment we have no news about the implementation of a new software version of the Winmor and Ardop modems by the Winlink developers, we are still waiting for news on the matter, so the only modem that can be used with the Winlink Epress program is the VARA SAT.

    Thanks to everyone who until now has helped with the tests to make the system work and improve with their reports


    Roberto IS0GRB

  • This evening, after other changes and adaptations, another great test with Oscar DJ0MY.

    He sent an email with an attachment of 100kB in 10 minutes with a constant speed of 2000bps.

    I made a video, that unfortunately has no audio because was selected the audio virtual cable interface.

    We can consider it a record through the QO-100 satellite in SSB.

    Link of the video:…7TZNMNZI/view?usp=sharing

    We have also reported some bugs to the author of the VARA modem, which will soon be resolved in the next software releases.


    Roberto IS0GRB

  • This evening Jose EA5HVK has released the version 3.0.5 of the VARA SAT modem.

    This version, at our request, integrates the Calibration function, very useful via satellite and for those without GPS.

    In the Calibration menu the client transmits a signal to the server, normally controlled by GPS, or to another client controlled or not by GPS, which reply with its signal and the shift detected by the client who launched the test.

    It is therefore possible to know your own AFC value detected by the correspondent and center the VFO, so as to reset the AFC to 0 (zero) without the aid of a WebSDR and therefore of internet connection.


    Roberto IS0GRB


    This is a test from my server:


    Like with all HF PSK based modes it is very important for high data throughput in VARA not to overdrive your transmitter and hence create significant IMD products degrading your modulation.

    There are plenty of tutorials on the internet explaining how to setup your station for e.g. PSK31 mode by watching the ALC meter of your radio very carefully. If you apply those settings to VARA, it should be working just fine and produce clean signals.

    Find below two spectrum examples that I have taken live from QO-100:

    One OM over-driving his TX in VARA mode and creating significant sidebands and resulting bad IMD as well as unequal amplitudes of the three PSK carriers of that VARA speedlevel.

    Also as a reference see below how a clean signal looks like in comparison with more or less equal amplitudes of the three carriers and no overdriven sidebands.

    73 de Oscar DJ0MY

  • Hello Oscar and thank you for this important report

    After various changes made by jose EA5HVK, today has released the VARA SAT 3.0.8, which integrates a function to follow the frequency drift faster

    Also, with all our tests, the author of the RMS Trimode Winlink server, just released a new version that solve a bug that did not immediately close the connection if the server reached the session timeout.

    I made a video during a connection with Gustavo PR8KW and with the help of Jose this bug has been solved.


    Roberto IS0GRB

  • Thanks Oscar, a REALLY important reminder!

    There have been some "interesting" examples of overdriven TX on the TP :)

    Thanks for your efforts too Roberto ( and of course Jose!)

    I have been playing with the unregistered version, and the results have been brilliant compared to HF - of course I can't send large messages/ attachments because that would take ages, but I am finding I get a 100% "ack" rate for what I do send

    I am looking forward to seeing if the Open Source methods can match the amazing work that Jose has done to get it all working so well:)

    Thanks again all

    Neil M0KNC

  • Hi SAT-friends,

    today I did my first test - BINGO!

    Sent and received first e-mails with the unregistered version of VARA.

    The SAT-link-calibration-function is super!

    Many thanks Roberto and Jose!

    Uplink: FT-857 / SCU-17 / SG-Lab-Transverter & PA (reduced to ~8W) / WIFI-planar-antenna RHCP (37x32cm) attached to a tripod on the windowsill.

    Downlink: 65cm offset-dish / mod. LNB with TCXO and 70cm output / FT-736R

    So far no GPSDO... ;)

    73 de Robert - DL5GAC

  • Hallo ....

    after upgrading to VARA Modem 3.1.1 and a new (faster computer) i got the following results on a first test with my (non GPS locked setup)

    Data Sent: 102384Bytes

    Time: 8min40

    Thruput: 11768Bytes/min

    looks ok for an SSB channel.... with 3kHz BW ....(nice!)

    Peak Datarate: 3500bps

    setup using:

    TCXO LNB with software driftcorrection on QO-100 BEACON (SDRConsole), ADALM PLUTO (TCXO MOD) in FULLDUPLEXMODE, SDR Console3.0.11 ,VirtualAudio to Vara Modem, RX/TX Switch ... VOX Controlled by SDRConsole

    73 de dg0opk

  • Good morning, after exactly one month of various tests and optimizations, thanks also to the availability and expertise of Oscar DJ0MY, Gustavo PR8KW and the author of the VARASAT modem Jose EA5HVK, we arrived at an efficient and high-performance system that allows you to receive and send emails at high speed if the license issued by EA5HVK is used.

    Unfortunately, without the license the speeds are low and we asked to Jose if it was possible to slightly increase the speed in the free version, to guarantee a ham radio free system worthy of the name.

    The server after 1 month of testing is now definitive and always operational on 10489635.

    The latest version of the VARASAT modem is 3.1.2.

    Thanks to all those who have tried the system, we will try to improve again


    Roberto IS0GRB

  • Hi Roberto,

    Congratulations for all job done, and happy birthday for your server.

    On my last test yesterday night, with my non GPS setup, was send 107903 Bytes in 8 minutes (07:51), bytes/minute: 13719, with 3.5kbps peaks.

    If Jose can increase speed for unregistered versions will be much appreciated.

    Maybe some HAM RADIO developers can help to implement ARDOP or even better ARDOPOFDM versions, as a second TNC option on QO100.


    Gustavo PR8KW