Posts by DK8KW

    Hello Thorsten,


    I am not familiar with the DX-Patrol up-converter but I assume that it is working as a linear converter. So what you would need is a relatively cheap step attenuator on thw input side of the converter to reduce the output power. This step attenuator only needs to be suitable for the input frequency and not for 2.4Ghz. I have seen those already for around 20 or 30 Euro.


    The SG-Lab PA is very linear, even down to very low power, see my report at


    SG-Labs 20 W PA V.3



    Vy 73


    Holger ‚Geri‘, DK8KW

    Hi Oliver,


    I have a different GPDXO, made in Germany by a company named Cartain. It was a bit cheaper than the Bodnar, and it was abvailable at the time I bought it and Bodnar had a longer delivery times.


    What I did was to check what peope said about the Bodnar-Voltage at 8mA and I basically use the same voltage with the Cartain. I only need a single GPS controlled frequency of 26MHz. I split the output through a Mini Circuits splitter (so at least losing 3dB) and then put another 3dB attenuator in the line before I feed the signal directly into the Pluto.


    The other line goes via a 20m coax cable to the LNB and stabilizes the reception. I am very happy with this entire setup.



    Vy 73


    Holger 'Geri', DK8KW

    HB9SKA: what my equipment is concerned, I don't believe in covers ;) ... my LNB as well as the helical antenna are in the open environment, so the front end of the LNB surely was wet during the rain. However, when a "normal" rain occurs and the surface of LNB lens is wet I can measure no attenuation.



    Vy 73


    Holger 'Geri', DK8KW

    Hello all,


    Yesterday I had the opportunity to record the level of the CW beacon while a heavy rain shower came down.


    The nominal value I adjust the beacon to is -73dBm. You can see from the picture that the lowest level during the rain is around -88dBm (only look at the upper values of the curve -- I tried to produce an envelope in Excel but that seems to be a challenge in itself).


    So the maximum attenuation is 15dB. My uplink signal, adjusted to the beacon level, also had the same attenuation as the beacon, which means, that the 2.4GHz signal seems to be much lesse affected by the humidity in the air.


    Did anyone else took similar measurments?




    Best 73


    Holger 'Geri', DK8KW



    P.S.: I don't really know if this is relevant and if the attenuation is the same for different antenna sizes. My QO-100 antenna is a 1.8 Meter offset dish from Kathrein (CAS 180).





    Hi Oliver,


    You were very brave to desolder the Pluto TCXO -- had somone else doing that for me. I also work with an external GPSDXO, also connected via a 3dB attenuator.



    Vy 73


    Holger 'Geri', DK8KW

    Hi Matthias,


    Thanks for the hint to Sigis recommendation. It worked!


    DO1OHB: Oliver, Sigi wrote in the beta tester forum for SDR-Console:


    "that is just easy cause you have TWO DRIVE sliders

    one in the tx options and one in the main tx dsp panel

    turn main at 100%

    then set the slider in tx options (search under "audio/gain") to your max allowed level (say 80% or so or if you have a high gain setup maybe only 50 or 60?!?)

    then you can not overdrie it anymore ... just do not set that slider higher as 80 ... in main tx box (dsp panel) you can then only turn it further down ... as an example ... i have set my drie in tx options to 85% and in dsp panel to 90 ... i can go a bit hgher if needed (crank up to 100 in dsp panel) but then i begin to have a bit of intermod (other call that splatter) ... so i set my level to be maximum where it is still clean in normal use ... and have some db left for voice peaks (or to break a pile up hi hi) ... and do not have the danger of overdriving the amp".


    Might be useful for your setup, too.


    That saves me at least an attenuator. :)



    Vy 73


    Holger 'Geri', DK8KW

    Thanks, Matthias,


    In the meantime i switched to an Adalm-Pluto and this is exactly the feature that I am missing in the Pluto setup (or that I am too stupid to find .. ;) ).



    Vy 73


    Holger 'Geri', DK8KW

    Hello Oliver,


    >And I know myself setting a Driver to 50% will be forgotten and 100% will be the standard


    Yes, I know what you mean. Thinks that can go wrong will go wrong Murphys Law). I have just send a feature request to Simon to limit the gain slider of SDR Console to a certain fixed vakue somewhere in the menues, so that a this value can only be exceeded if really needed and not in day-to-day operation. Hopefully he will come up with a solution.



    Vy 73


    Holger 'Geri', DK8KW

    Hi,


    I can second, what Oliver writes. I also received the V3-PA yesterday and did some tests and measurements and I am very happy with this new version. I already use the V2-Version in my portable setup, perfectly fitting to the output of the BU500 up-converter.


    The RF-Vox is irritating at first, because when you connect the PA to 28 Volt there is almost no current. The build-in ampere meter of my lab power supply only shows 2 digits after the decimal. I only saw "0.00" and thought, that the PA was not working. However, as soon as the input power is raised above a certain threshold (in my setup around -3dBm), the RF-VOX kicks in and the current rises above 0.6A @ 28V.


    You can also activate the PTT permanently and this leads to a bias current of 0.58A. With the PTT activated I was able to amplify signals of down to around -30dBm, resulting in an output power of around 0dBm, so the amplifier is also well suited for QRPP-experiments.


    All my measurments confirm the claims of SG-lab. I mounted the amplifier onto a heat sink with dimensions of 15x20x2cm and even at transmissions at 20 Watt output, the housing of the PA only got slightly warm.


    The plan is to install the amplifier outside in a waterproof enclosure close to the 1.8m offset dish and possibly also start some experiements with DATV on the wideband transponder later this year.



    DO1OHB: Oliver, I would not be too concerned about putting an attenuator between the pre-amplifier and the PA. The pluto gain itself can be adjusted pretty linearly, and if you set your Pluto drive somewhere between 30 and 50, you already should be in the usuable range for the input of the SG-Lab Pa. The maximum input of the PA is 20dBm, and even if you accidently set the Pluto-gain to 100% you will most likely not exceed this level, because SMA plugs and cable between the pre-amplifier and the PA will have more than 1dB attenuation.



    Vy 73


    Holger 'Geri', DK8KW

    Hi,


    While I agree that the full duplex operation is very useful, my interpretation of the rule


    "Full-Duplex operation is mandatory (you must be able to monitor your own downlink while transmitting!)"


    is that I am able to MONITOR my signal, not necessarily permamently to listen to it.


    It would make me completely crazy if I had to listen to my own CW transmission with the delay of the satellite link and the SDR processing. So my way to comply with the rules is that I have SDR Console running and closely look at my own signal while I transmit. This allows me to see if anyone wants to interrupt me, or if my signal gets distorted in any way or my signal strength accidently rises above the beacon level.



    Vy 73


    Holger 'Geri', DK8KW

    Hi folks,


    I recently modified a few Airlink 60 antennas (see figure 1). This industrial 2.4GHz antenna is made by SSB Electronic. The original antenna has a vertically polarized patch in it, made by GlobeSat in Denmark. This patch is glued in the focal point to the inside of the radom (see figure 2).


    I replaced this patch with a WA5VJB-patch, LHCP (Hi Z to compensate for the effect of the radom, as recommended by WA5VJB), so that the antenna is transmitting right hand circular polarization (RHCP) (see figure 3).


    As I have a few of these antennas available, I could directly compare the circular antenna with the vertical linear one. The difference I measured in my QO-100 signal strength was between 2.1 to 2.5dB.



    Best 73


    Holger 'Geri', DK8KW




    Figure 1: Airlink 60, an industrial prime focus dish made by SSB Electronic.




    Figure 2: The inside of the antenna can be accessed from the back. Here, the original linear (vertical) polarized patch can be seen.



    Figure 2: The original patch was replace with a WA5VJB patch.

    sv8qg


    Hello Alex


    >I’m wandering if I can paint the hole POTY with plastic paint


    I have no experience with the Poty, however, when I tried to glue parts of a helical antenna to the isolator I used a two component plastic glue. That immediately changed the entire resonance of the antenna and I quicky had to remove the glue again.


    So I recommend to check the electrical parameters of the plastic paint first. You might use a sheet of plastic material and check, if it gets warm in the microwave oven. If not, paint it with the plastic paint you want to use. If that doesnt warm up it might be OK.



    Best 73


    Holger 'Geri', DK8KW

    SWL-SK89


    Can you access this settings-windows? Maybe you got some wrong figures in there.


    For the unmodified Pluto, the value should be 40000000 Hz. I am using an external 26 MHz reference, that's why the value here is 26000000 Hz.



    Best 73


    Holger 'Geri', DK8KW




    Hallo Mike,


    allgemeine Suche bei Google mit den Stichworten 'ebay BU500 up converter' hilft bei mir -- das Teil taucht dann sogar in ebay. de auf.


    Ich bin selber begeisterter Nutzer des kleinen Konverters. Eines habe ich leider kaputt gemacht.


    Das andere betreibe ich mit KX3 und 50MHz als ZF in meiner Portabelstation mit SG-Lab Endstufe dahinter -- funktioniert ufb!



    Vy 73


    Holger 'Geri', DK8KW

    Hi,

    The only point that is under investigation is if available 2.4 GHz filters are drop image from 70 MHz IF from your 7300.

    Hello folks,


    interdigital filters would do that but probably would not help with a low budget rig, unless one is capable of building one homebrew.


    I use this interdigital filter from ID-Elektronik to successfully run a BU500 up-converter with an IF of 50MHz.



    Vy 73


    Holger ‚Geri‘, DK8KW


    Adalm-Pluto is USB-2 but I connect it to the USB-3 socket and I have never had problems and no need to apply external power.

    Thanks for the information, Lucio.


    I have now connected the Pluto to a USB 3.0 card, that is supplied by a separate cable directly from the computer internal power supply. So far everything works fine :).



    Best 73


    Holger 'Geri', DK8KW

    has anyone had good success with this board / pcb


    Hello Sean,


    I purchased an already modified Pluto from Joerg, with the TCXO built in. It works very well. In the meantime I modified the device so that I also can feed in an external GPS disciplined 26MHz signal. This modification was easy, because Joerg already did the difficult part of the modification: removing the Pluto's internal oscillator.



    Best 73


    Holger, 'Geri', DK8KW

    If the Pluto is connected with two power sources on both ports in parallel, you can damage the Pluto.


    Hi folks,


    My Pluto is connected with the USB-cable to the computer and, with the second cable, to an external 5V power supply. When I connect or disconnect the external power, the Pluto resets and restarts -- obviously now switching to the power from the computer's USB port. This function seems to prevent that two power sources are used in parallel.


    I prefer to run the Pluto on external power, because the device permanently draws around 400mA, which might be a little bit high for a regular USB-port, especially if the computer also powers other external devices.



    Best 73 and stay healthy!


    Holger 'Geri', DK8KW

    Hello Matthias,


    This morning I made use of the beautiful weather here in Peine to quickly set up the Cassegrain in the garden and to do a quick test on the SNR.


    After carefully adjusting inclination, azimuth and skew (much more carefulyl than I usually do when I quickly set up my portable equipment) I measured a "SDR-Console-SNR" of 31.3dB.


    Provided we use the same bandwidth (I typically use 550kHz to see the entire transponer and a little bit beyond) our two values do not seem to be so far off. Adding the 1.5dB loss that DH1ND claims to have measured due to his "Helix-Reflector-Peekhole" a difference of around 2dB remain. Good enough for me ;).


    I am sure you know that by lowering the window-bandwidth you can almost achieve any measurable SNR with SDR Console (see pictures).


    Widh a bandwidth of 550kHz I get the 31.3dB SNR.



    With 2.7kHz bandwidth I get over 44dB SNR.




    I believe that the 31+dB are plausible. With my fixed setup and the 1.8m offset dish I get an SNR of 41dB (@ 550kHz bandwidt). At 10.489MHz the 1.8m dish has about 10dB more gain than the 0.6m dish, so the SNR difference should also be in the same ballpark figure, isn't it?



    Best 73 and stay healthy!


    Holger 'Geri', DK8KW