Posts by DK8KW

    Hello all,


    I have got my SG Labs 20-Watt-PA yesterday. I like the feature of measuring the input and output power as well as an SWR estimation by measuring a voltage.


    What feedthrough capacitors would you recommend?


    It should be a small diameter feedthrough capacitor and it would be great to have a metric thread, so that it could be directly screwed into the PA housing.



    TNX, best 73


    Holger ‚Geri‘, DK8KW

    Hello all,


    There is a guard band allocated 5 kHz around the beacons, in which no transmissions should be made. Recently I have had a few instances where the SDR-Console lock to the engineering beacon on 10.489.800 MHz was lost due to stations operating too close to the upper beacon.


    It wouldbe nice if you could keep that guard band free from transmissions. Perhaps you can also inform others who are not on this forum.



    Thanks, best 73


    Holger 'Geri', DK8KW

    Hi Lucio,


    I tried my luck yesterday but with my relatively small antenna (Wimo X-quad) I had no luck this time. The sun was too close to the moon and I had a lot of noise to fight. But I agree with you, it was a great adventure and for me it was the first time to receive a signal originating almost 400.000 km away. I was lucky and received the satellite a few times during the past couple of months with my small setup, somewhere in the fields where the man made noise is low. It was a great experience!


    Vy 73


    Holger ‚Geri‘, DK8KW

    I0LYL thanks for the information, Lucio.


    Rohde & Schwarz also have some useful free tools here:


    https://www.rohde-schwarz.com/…ion-note_56280-15492.html


    I like especially their dBm Calculator, which I have installed on my tablet and my smartphone (iOS). It is also available for Windows, Mac, Android, etc.


    I do my complete power level and link budget calculations with it. It simply allows mixed calculations in dBm, mW, W, dB.


    Best 73


    Holger ‚Geri‘, DK8KW



    DF6LO , thanks, Matthias, for your extensive calculations and considerations.


    I wonder if the results of the current so called experimental tool BEMFVDish.exe will be accepted by the BNetzA.


    Well, we shall see! I submitted my sketches and some of the calculations to the BNetzA and didn't get any feedback yet.



    Best 73


    Holger 'Geri', DK8KW

    Hello together,


    I can comfirm what DL5RDI said: the permanent TX-modification is neither necessary for SSB nor for CW. In my view the only valid reason to do this modification is when you want to reduce the power for whatever reason, for example to test low-power (below noise floor) data communication. As the HF-VOX switches only above a certain input power (in the range of 5 dBm), you can further reduce the input power only if you did this modification.


    From my experience I can also confirm that this amplifier can produce around 2 to 3 Watts, not much more. For a brief moment I got about 5 Watt output, but not for long, and not reproducable (unmodified PA).



    Best 73


    Holger ‚Geri‘, DK8KW

    Hello all,


    I agree with what pe1hzg said regarding the possible zone of exposition to radiation. In Germany we have the principle that I have to protect people outside of the „Controllable Range“, which is basically my own property.


    I submitted this sketch as a part of my documentation for the authorities. In order to save a new submission in the future I entered 75 Watt (minus a few dB for cable/plug losses) in my documentation. 75 Watt PEP is the maximum allowed power for class A. currently I only use 750 mW ... :)



    Vy 73


    Holger ‚Geri‘, DK8KW



    DF6LO : In the latest „Watt32“-package that I downloaded from the DARC website there is a program called „BEMFV Dish“, written by DL9KCE. In this software you can calculate the so called „Leistungsflussdichte“ for antennas such as parabolic dishes.


    In most cases the value is way below any critical values. Not the EIRP is important for our cases but a value in Watt per square meter (antenna area). As our antennas point upwards into the sky, even the main radiation is well above people or animals, even if they are fairly close to the antenna.



    Best regards


    Holger ‚Geri‘, DK8KW

    Hello all,


    I use the old ARRL-way of "best guessing" by ear:


    1 - Faint signals, barely perceptible

    2 - Very weak signals

    3 - Weak signals

    4 - Fair signals

    5 - Fairly good signals

    6 - Good signals

    7 - Moderately strong signals

    8 - Strong signals

    9 - Extremely strong signals


    Any signal around the beacon signal for me is in the S9 range (as suggested by Peter). People who just make it a few dB above the noise get an "S1 or S2" from me.



    Best 73


    Holger 'Geri', DK8KW

    DF2IC , Greg, at first I tried a similar setup, also with the Ukrainian transverter from 28 to 432 MHz. In order to stabilize the oscillator I put in a small 12-Volt light bulb and placed it very close to the oscillator at the edge of the transverter board. At least that helped to speed up the warming-up process.


    In the meantime I totally changed my strategy and use the Taiwanese BU-500 up-converter with an IF of 50 MHz. However, in this case you should use a good filter, I use a specially-made interdigital filter made by ID-elektronik. It has a notch filter for the LO frequency of 2350 MHz that attenuates that signal by more than 90 dB!.



    Vy 73


    Holger 'Geri', DK8KW

    Hello all,


    This week I used the occasion of a business trip to Bochum to receive the source of the DL50AMSAT beacon signals on QO-100 directly, instead via a detour of over 75.000 km.


    Reception equipment:


    - Norsat Model 2500 converter, converting 2.400 MHz to 122 MHz (price was only 16.- US$ on eBay a few weeks back!),

    - 9-element WLAN Yagi (not really necessary in this case but I had it connected to the converter anyhow ...)

    - NOOELEC RTL stick and

    - SDR Console software.


    Between the converter and the SDR-stick I used a switchable attenuator due to the strength of the signal (distance to the transmitter was only about 50m).


    Here are a few pictures of my little expedition.


    It was Monday, so the Sternwarte Bochum was not open to the public. Nevertheless, gates were open so I also was able to explore the area a little bit. The DL50AMSAT signal is being transmitted from the 3m-dish directly behind my shoulder.


    With the same setup, by the way, I was able to receive the beacon DB0GW in Duisburg on 2320,85 MHz over a distance of about 7km.



    Best 73


    Holger 'Geri', DK8KW



    Hi all,


    Here is a quick and dirty bersion of a double feed holder. The LNB is exactly in the focal point, the helical feed was adjusted using a laser pointer so that it looks into the center of the dish. I use approximately 750 mW for a signal that is as strong as the CW beacon.


    The trick here: the dish is a 1.8m offset antenna (Kathrein CAS 180) so that I probably can afford a few dB loss due to the fact that the uplink feed is a bit off the focal point.



    Best 73


    Holger ‚Geri‘, DK8KW

    Hello all,


    I am on the road, setting up my portable equipment whenever there is time. On Friday I was qrv as M0KWD/p near Harwich, yesterday and today as MW0KWD/p from Swansea in Southern Wales. I will be travelling until later this week.


    My setup:


    TX: KX3 with 50 MHz IF into the BU500 up-converter, followed by an interdigital filter with a 90 dB notch at 2350 MHz, then a WIFi Pa, about 2 Watts into a 60cm dish made by SSB-electronic.


    RX: also 60cm dish (Cassagrain reflector) with GM-201 LNB, SDR Console software. Both on a portable camping dish stand.


    My experience: setup and orientation is easy, I use my smartphone with a levelling app to measure and adjust the inclination and the compass to find the right direction.



    Thanks for those who have the patience to listen to my weak signal.


    Best 73


    Holger ‚Geri‘, DK8KW


    Hello all,


    I do have this new V06 version in operation and I am a happy user.


    As IF-Exciter I use 50 MHz from a KX3, running 100mW plus a 10dB step attenuator. With the previous Version*, I had full output of the LO frequency of 2350 MHZ even with no IF signal injected. Now, with the new version, the LO is sufficiently suppressed so that it does not produce any visible output on the smallPA behind the BU500. Just to be on the safe side, I do use an interdigital filter specifically built and aligned with a deep 90dB notch at 2350 MHz (made by ID-Elektronik).



    Best 73


    Holger 'Geri', DK8KW


    *) I mechanically damaged the previous B500-version when I attempted to drill a separate hole in the little housing. It is now sitting on my shelf waiting to be repaired ...

    Hello all,


    The SDRuno-Software in combination with one of the SDRPplay-devices (I use the RSP1A) is capable to measure/estimate the SNR reasonably well. The SNR is calculated based upon the selected bandwidth.


    To quote SDRplay Tech_Support:.


    "The SNR measurement is only for the selected signal as defined by the filter bandwidth defined within the Rx Control panel. The signal power is taken from the power meter measurement and the noise is estimated via an analysis of the entire wider band noise floor within the SP1 window to remove the effect of the presence of other signals. As such, the SNR measurement is not a precise measurement, but it is reasonably accurate."


    [see: https://www.sdrplay.com/community/viewtopic.php?t=2947]



    Vy 73


    Holger 'Geri', DK8KW

    Hi all,


    Thanks to all the hints from Marcel and others here in the forum I have managed to successfully watch a number of DATV transmissions in the meantime.


    Two things were particularly helpful: more computer power (I upgraded my PC from a dual core to a quad core) and the increase in signal strength. Sinde a few days I do have a 1.8m offset dish from Kathrein standing in my garden and the improved signal to noise ratio definetely has reduced the required computing load during decoding of the signals.


    I am looking forward to the next version. Thanks, Marcel, for working on this software!



    Vy 73


    Holger ‚Geri‘, DK8KW

    Hi,


    After finding a (relatively) cheap Quadcore-Computer (Intel Q8400) reception now works fine, using an RSP1A and a modified Octagon (IF around 435 MHz) in a 85 cm offset-dish.


    Finding rhe right parameters still meams fiddling around a little bit but once I hit the proper parameters the stream starts and the video is escellent.


    Thanks, Marcel, great software.



    Vy 73


    Holger ‚Geri‘, DK8KW