Posts by DK8KW

    Already back in 1984 there was a software called "Dr. DX" for the Commodore C64, simulating an entire shortwave contest with varying band conditions, greyline dx, pile-ups and rare stations showing up and disappearing again throug out the game. There was not even the need for any other ham station to have fun ... ;)



    Vy 73


    Holger 'Geri', DK8KW

    I am asking because stations calling the the dx station will most likely not be listening on their split tx frequency while calling and therefore not hear the LEILA warnings.

    ... the good thing with QO-100 is: a rare dx station will create a pile-up at first, but if you are a little bit patient and give it a few days, the dx station will call you in the end. The amount of stations accessing the satellite (currently) simply is too low to create an hour-lasting pile-up.



    Best 73


    Holger 'Geri', DK8KW

    @SWL - markro92: marcel, thanks for the new version. I have been playing around a little bit with it and it seems to be decoding faster with the new version.


    >Showing Ku-Band Lo/Hi frequencies next to IF frequency.


    What I tried to do is to adjust the frequency offset in the device.ini-file but without success. I use a modified LNB and my L.O. is around 9.500 MHz. I am also missing the readme.txt file that supposidly is explaining on how to set up the parameters.


    How can I adjust the L.O. frequency so that the correct receiving frequency is shows?


    Update: I just played around a little bit and found out, that the frequency in the devices.ini is not the L.O. frequency but the current reception frequency stored with the device. So we have to see what the next version brings ...



    Best 73


    Holger 'Geri', DK8KW

    Hello all,


    For those of you who want to equip the SG-Labs 20 Watt PA with the additional voltage outputs to measure input (DRV) and forward (FWD) power and estimated SWR (REF), here are a few pictures showing that it is an easy task.


    What is needed is just a 2.5mm drill, a tool to cut the M3 thread and steady hands. Wiring is also easy.


    As you can see, I operate the PA with a 12 Volt to 24 Volt up-converter that I found somewhere on the internet. I mounted both devices on the same aluminium heat sink.





    Here is a detailed data sheet of the L4030-034N


    L4030-034N.pdf




    Vy 73


    Holger 'Geri', DK8KW

    SWL-JanV : I can confirm what DB8TF writes. I use 50 MHz as an IF, so the 2350 MHz signal of my older type BU500 had the same problem. I ordered an interdigital filter from ID-Elektronik (I am not very good doing precise mechanical work). The filter has a 90dB notch at the L.O. frequency of 2350 MHz and the problem disappeared.


    Meanwhile (after mechanically damaging the old-type BU500, trying to drill some holes into the housing) I ordered a new one (Version 6) and the problem disappeared. Nevertheless I keep the interdigital filter in the signal path, between the BU500 and my PA, just in case.



    Best 73


    Holger ‚Geri‘, 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