Posts by DJ0MY

    The stability may be better with a non-tunable one and any frequency error can be corrected through adjusting the pluto offset setting. This setting is held in flash and retained on power cycles.

    Hi Mike,


    sorry for hijacking this old one :)


    When you say "pluto offset setting" which is held in flash:

    Do you refer to the reference frequency command that you use via the serial terminal?

    The same commands you use when you change e.g. from 40MHz to another reference frequency?

    If so, does that have actually sufficient Hz resolution for very fine offset tuning? Or is there a seperate command for offsets?

    (I didn't come across in internet)


    I am just working on another project where it could come very handy to store a fine offset in flash.

    (rather than correcting it externally, like e.g. in SDR-Console instead).


    73, Oscar DJ0MY

    He explains it also here why the SNR cannot be zero:

    https://www.sdr-radio.com/s-meter



    Note:

    When no signals are present with the SNR display it is quite normal to see a SNR reading. This is because Noise is the mean (average) whereas Signal is the peak value, so even in a quiet part of the band there will be a difference between the peak and mean. To see this yourself change the Smoothing algorithm to None (Ribbon Bar, View, Spectrum, Smoothing). The default smoothing is very good at eliminating noise.

    You see the same effect with a 'normal' receiver which has a S meter - even on a quiet band it will be moving and following peaks in the noise.

    Roland wrote: The SNR should be ZERO with no signal and should not change according to the zoom level!


    This was already discussed long time ago on the SDR-Radio support list after Simon introduced the SNR feature into the S-Meter. It seems that it is not a bug, but a feature :)


    However, the change when zooming seems indeed a bug, hi hi...



    73, Oscar DJ0MY

    RIT gibt es im linken RX Fenster ein bisschen weiter unten (auch XIT)....

    Aber wahrscheinlich nur bei "sendefähigen" SDR Typen, z.B. Pluto SDR.

    (Du hast nicht geschrieben was für ein SDR das ist)


    73, Oscar

    Do I interprete it right, that in the mixed mode segment 2700Hz BW limitation is suggested for "normal mixed modes", but that this does not apply for the "special purpose" use, as nothing is mentioned ?


    The only remaining question would be, what qualifies for "special purpose"....? And should this be done in agreement with AMSAT?


    Oscar

    I reckon more than 1700 POTY's (kits) have been made. So there is potential activity enough. Furthermore there must be an RF incentive (i.e. make stuff for 2.4 GHz narrow band) to become active on the NB transponder. Making stuff for 2.4 GHz uplink seperates boys from men ; -)

    I guess there could be a significant percentage who built two POTY feed kits.....for example myself I got two of them (one bought spontanously at Friedrichshafen Fleamarket). Using one on my permanent dish and one for my portable station :)


    And I am still missing one important QSO in my collection - that's with DB2OS himself, hi hi


    73, Oscar

    Would be indeed interesting to have some weak signal mode 2.4GHz QRP TX...is there a design perhaps already existing somewhere?

    Would be also cool for APRS positioning like applications, e.g. from a driving car into a QFH helix or a patch on the roof.

    Or for amateur baloon payloads, etc.


    73, Oscar

    Maybe of interest for OM/YL still looking forward to modify a Pluto SDR for NB use, but are afraid of the hardware mod...


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    Hi DG2SBL,


    based on my experience the internal TCXO is quite accurate and has only a very tiny drift...something like 100-150Hz during warming up or in-between transmissions.


    Specially noticable when operating outdoors at cool temperatures (bigger temperature differences than indoor use). But I also noticed the drift indoors.


    I think for SSB work this is fully acceptable and almost not noticeable. I used it in the past at home with and without GPSDO.

    Now I use it only for my portable station and always without GPSDO, since I do not want to carry so much equipment, hi.


    The external 10MHz reference + GPSDO is therefore only required if you really want to be "rock solid" on frequency.


    73 de Oscar DJ0MY

    They are two Russians - conversation very roughly like this:


    They guy asks the other:

    "Hello, hello

    "How much are you running - a Kilowatt?"

    "A hundred"

    ""Blah, you are going well - should we go there or stay here?"

    "we can go there...away and see further"

    "OK lets go pilgrim.."


    73 de Oscar DJ0MY

    You have a clever son. This looks a neat solution for the SMD challenged.


    I would advise against using the tunable TCXO. The stability may be better with a non-tunable one and any frequency error can be corrected through adjusting the pluto offset setting. This setting is held in flash and retained on power cycles. Also be aware some TCXOs tuning voltage moves the frequency in discrete steps so you will find setting it exactly not to be possible for those devices.


    Mike

    Hi Mike,


    thanks for your suggestions.


    I was not aware that the Pluto could also permanently store correction settings in flash. I thought it would always rely on external software to do so. But you know - some hams like to turn knobs and not hack something into a console. hi hi:)


    The tunable version is widely in use (as it was widely propaged by Sigi DG9BFC) with no bad experience so far as compared to its fixed frequency counterpart.


    I am using it since August this year in my Pluto openly wired (see photos attached) and once tuned to the right frequency it never had to be retuned so far. Also the tuning is really smooth and sounds very analog style - therefore no discrete steps in this model noticeable as it seems...


    Oscar

    Dear friends,


    we have been busy over the past weeks designing a TCXO breakout board for the Pluto SDR.


    The purpose is mainly to support people that are afraid of soldering these tiny 1.6 x 2.0 mm sized TCXOs. With the help of this ready-made breakout board modifying a Pluto SDR should be much more accessible to the average ham.


    This project was supporting the purpose to teach my 11 year old son how to use KiCAD and getting him interested in our hobby. Most of the schematic drawing and manual PCB layout was done by him with only very little support from my side. I am very pleased about the result and the learning curve of my son. :thumbup:


    In the attached KiCAD 3D images you get an idea how the final board would look like.


    It uses the famous ABRACON ASVTX-13-C-40.000-I05-T (40 MHz, 1.8v, 0.5ppm) which is very stable when mounted away from the TRX chip, next to the FPGA. This is the VCTCXO version with frequency correction pin to set the clock to EXACTLY 40 MHz via a small SMD multi-turn potentiometer soldered onto the PCB.


    This TCXO model is "The Model of Choice" for most Pluto SDR users on QO-100, due to its superb performance for NB transponder use. You can find many references about this TCXO model on the web with many happy users. The only limitation so far was, that this modification was only suitable for SMD experts due to the extremly tiny size.



    See the attached photos of the PCB with the drawing on how this breakout board is supposed to be inserted and connected. It is just fixed at the right place with double sided scotch tape and then wired.



    We are planning to have a first batch run of professionally produced boards made in a SMD fabricating house. This means we will be able to offer this PCB ready made with all components already factory soldered as a simple kit. The board size is approximately 7x15mm with some easy to solder pads for the wire connections.



    A documentation and YouTube instruction video will be provided once first batch is available. (also including an "easy method" for removing the original XO from the Pluto)


    73 de Oscar DJ0MY (and Daniel - my 11 year old desginer)

    Yesterday the special permit in Spain has expired.


    The good news is that there is a new special permit for using QO-100 uplink frequencies with effect of yesterday 26th of September 2019 and valid for one year. You can find here the new permit.


    The permit is worded to be valid for all "holders of valid amateur radio licenses".

    While not being an advocate in my personal view this wording could be interpreted that it is also valid for all foreign hams operating under CEPT license in Spain.


    The general rules were modified slightlty:

    • no mode restriction anymore to phone mode as in previous permit (this means now all modes including DATV should be legal)
    • restriction is still limiting to a maximum of 1500W ERP
    • NEW: the station must use an antenna with not less than 22.5dBi Gain


    I guess the last point is to avoid local interferences of other services, by use of a highly directive antenna.

    (I guess for circular polarisation you can remove 3dB from that value, hi hi ;))


    Permit is on a non-interference basis and in case of interference to other radio services all transmissions need to be stopped with immediate effect.


    73 de Oscar DJ0MY

    Yesterday the special permit in Spain has expired.


    The good news is that there is a new special permit for using QO-100 uplink frequencies with effect of yesterday 26th of September 2019 and valid for one year. You can find here the new permit.


    The permit is worded to be valid for all "holders of valid amateur radio licenses".

    While not being an advocate in my personal view this wording could be interpreted that it is also valid for all foreign hams operating under CEPT license in Spain.


    The general rules were modified slightlty:

    • no mode restriction anymore to phone mode as in previous permit (this means now all modes including DATV should be legal)
    • restriction is still limiting to a maximum of 1500W ERP
    • NEW: the station must use an antenna with not less than 22.5dBi Gain


    I guess the last point is to avoid local interferences of other services, by use of a highly directive antenna.

    (I guess for circular polarisation you can remove 3dB from that value, hi hi ;))


    Permit is on a non-interference basis and in case of interference to other radio services all transmissions need to be stopped with immediate effect.


    73 de Oscar DJ0MY

    Hi Ismo,


    very simple - it's just done like with most other SDR programs by mouse dragging:


    Go with the mouse over the dividing frequency scale between spectrum and waterfall and you see the mouse cursor change.

    While the mouse cursor is changed you can now hold right mouse key and drag it up/down to change size ratio of sectrum vs. waterfall.


    Enjoy.


    73 de Oscar DJ0MY

    Hallo,


    ich habe das heute auch mal getestet mit SDR Console 3.0.13 und aktuellster FW 0.31.

    Auch hier ist bei einem Singletone Signal ungefähr auf Bakenstärke eingestellt die Nebenaussendung auf 2400 MHz über den QO100 zu sehen. (allerdings bei mir viel schwächer als bei dem eingangs von DK5FA geposteten Screenshot)


    Als Gegenprobe habe ich dann mal mit SDR Angel gesendet auf der selben Frequenz und auch hier stelle ich die Aussendung auf 2400 MHz fest bei Aussendung eines Singletone Signals auf CW Bakenstärke.


    Allerdings ist davon bei SSB-Modulation und auch beim 2 Tone Test (mit SDR Console Standardeinstellugen) nichts mehr über den QO100 Transponder zu sehen. Da scheint das Signal zumindest unter das Transponderrauschen zu fallen, sofern es noch da ist.

    (leider kann ich nicht direkt auf 2.4 GHz mit Specki oder SDR messen)


    73 de Oscar DJ0MY

    Almost right - you forgot the 120pF & 330nH in series to be added to the F connector pin, too. (and from there a short wire to the PLL chip input)


    See the pictures attached to the first message in this thread.


    For the rest it seems you understood it correctly.


    73 de Oscar DJ0MY