Posts by df2et

    Dear guys,

    this is a short how-to on how I did modify the Opticum LQP 04H LNB:

    After Octagon is currently not able to provide more PLL based LNBs to be used for SAT mode I decided to have a look at Opticum LQP 04H types. Those are also sold modified by AMSAT-DL for use with their down converter v3 (see [1]). My portable setup is also based on such a unit so I wanted to try a mod of the quad model in order to also connect an SDR stick in parallel (or a DATV SAT RX or whatever).

    This type of LNB uses the same case as the twin variant. Only the PCB seems to differ slightly. The 25MHz crystal sits right in the center on the PCB under a metal shield that can be removed by unscrewing 4 torx screws. Removing the crytal is a little tricky because it is glued to the PCB. I did this by using two soldering irons in combination with a sharp knife to lift the crystal while heating.

    Anyway the crystal came off including the pads. Not sure if that would have work properly without heat as there are two traces nearby that could easily be damaged from hard mechanical force. The picture above shows the opened LNB with crystal removed.

    In this variant I did not cut off one of the IF outputs to feed the reference but instead built a low pass filter into one of the outputs in order to be able to use all 4 outputs. In this case I chose the connector at the very back of the LNB. The printed inductance was cut as a 2u2 coil inserted. This is the component at the bottom on the following picture.

    Above the IF trace feeding the output at the very back there seem to be a “patch panel” of unused pads. So I did mount a 120pF capacitor and a 330nH coil from the IF trace to those pads. The reference frequency is then using a short thin wire connected to one of the pins of the RT340 where the original 25 MHz crystal was connected. It is the third pin counted from the corner of the chip. The wire is soldered to a small via located just in front of that pin. You may need to remove some of the solder stop paint before.

    Now you can feed a 25Mhz (or other arbitrary offsets) into the back most connector while using it as an output. I.e. connect the WB port of the AMSAT-DL down converter here. The other 3 ports can be used as normal outputs (H/V depending on the voltage fed).


    vy73 de Florian DF2ET

    Hi folks,

    last night it happened. We were able to pick up the first (CW) signals from Felix on the Georg-von-Neumayer station operating as DP0GVN in Antarctica. After some preparations we observed a really ufb signal from IB59. A short video can be found in my Tweet:

    A neat little pile-up in CW followed after we completed the first QSO.

    A little while later we wittnessed the first contacts in SSB. This time Charly DK3ZL currently operating as V55QO in Namibia was the lucky one to have the first QSO. Felix then returned around 2200z for some more SSB operation. This time he was facing a really large pile-up and after ~ 1 hour he had like 100 QSOs in the log. During the operation you could see the big smile in his face while listening to his answers in split-operation.

    Felix is expected to stay in Antarctica for another few weeks. So hopefully more OMs and YLs will be lucky to catch him on SAT.

    vy73 de Florian DF2ET

    Hi Heiner,

    we did ~ 50 QSOs with the special callsign on Sunday. Will provide the .adif file, so that all those guys can get a proper QSL card.

    vy73 de Florian DF2ET

    Switching off complete power supply sometimes will help. I have had similar problems with old A version. After update/repair to version B this problem seems to be solved.

    Switching power on and off did not help in this case. My unit has been updated/reparied to model B earlier this year. So this obviously also happens to model B units ... :(

    Hi Ed,

    tnx for your support. I think it is not a problem with SWR as I tried various dummy loads and atennas. Also the SWR LED on the front panet should have ligted up in this case. But that did not happen. PTT works as the PTT LED turns red in case of transmissions. Besides that the SWR shutdown should be detectable using the serial terminal. But reading that also does not indicate a SWR problem.

    In fact I did return the unit yesterday and am now waiting for an information by the manufacturer. Let's see what happens.

    vy73 de Florian DF2ET

    Hi @ll,

    I have a Kuhne MKU UP 2424A up converter in use since February. During my /p activity from PA the converter obviously suddenly died. It does not output any power any more. The input settings were not modified. It happened just between two QSOs (or after a QSO as the next calling station could not be answered any more).

    Has anybody of the Kuhne users experienced such a problem? I heard of one case where this symtom also happend but the converter came back to life without any further action some days later.

    In my case this does not apply apparently and the converter is still dead ...

    Any hints or help much apprechiated.

    vy73 de Florian DF2ET ;(;(;(

    kann jemand reflow SMD löten? Habe Teile für DB4UM PA.

    pse hlp! =O

    (looking for help in reflow soldering here in Germany)

    tnx de Michael

    Hi Michael,

    ich habe einen Reflow Ofen und eine HotAir Station da. Die Platine und die Teile liegen auch schon bereit. Mit beidem sollte das kein Problem sein. Ich empfehle Lötpaste mit (hohem) Flussmittelanteil. Damit sollte es problemlos gehen. Ich nutze z.B. CR 44 von Reichelt:…-p6833.html?&trstct=pos_0

    vy73 de Florian DF2ET

    Dear OMs,

    walking around the flea market on HamRadio in Friedrichshafen we ( DG3YJB  DL5APR  G4KLX  DL1YDD with DL5BQ and G6WBJ) found some guy selling a 40cm dish for 8€. After we bought all of those we had a quick experiment at our holiday flat that we were staying in during the fair.

    After wiring up the commonly used setup (LNB -> BiasT -> SDR Stick) we could cleary decode the CW beacon and even listen to SSB QSOs. May those pics inspire people with limited capabilities to setup a QO-100 station ;-)

    vy73 de Florian DF2ET


    Absolutely no problem. Just wanted you to have that on the list for next year. If it's on there already I am fine.

    Besides this minor issue I found the meeting to be very useful and I would appreciate if we manage to have a similar meeting next year. Thank you for organisation.

    vy73 de Florian DF2ET

    Hi Johannes,

    I did have a talk to the Kuhne guys at HamRadio in Friedrichshafen and asked for the details of the reference input of the modified MKU 2424 A converter. They referred me to the manual for the recent B version where you can read as attached in the image. See below. It also applies to the factory-upgradede MKU2424 A.

    vy73 de Florian DF2ET

    2. The prices on the dinner menu were much higher than shown in the standard menu. I think approximately 20% more. I know that restaurants have a service charge for big groups, but that does seem excessive.

    I can confirm that. At least item No 2 from the menu was 25% more of the price at it was on the ordinary menu. :(((

    Besides that the food was fine and the talks and the meeting itself were very good!

    Hi @ll,

    I also got my repaired/upgraded KMU UP 2424 A back a few days ago. But I am still missing the updated manual concerning the REF input. In the meantime I upgraded the case and added a SMA/UFL pigtail.

    Did anybody test with an external reference yet?

    vy73 de Florian DF2ET

    Hi @ll,

    besides all rumours that it would not work we tried to decode the DATV bacon on the WB transponder with a "standard" satellite receiver and tested successfully. Downlink via 90cm offset dish, an Octagon Greed Quad LNB modified by me for external reference and a Dreambox DM8000.

    The LNB was fed with 24.3MHz from a LeoBodnar GPSDO to shift the IF of the WB transponder to the input of the SAT RX. Using a manual scan we found A71A and could watch the demo on a flat screen. A short recording is uploaded to YT:

    vy73 de Florian DF2ET

    Tag zusammen,

    in Anlehnung an die vom BATC beschriebene Modifikation des Quad LNB OQSLG von Octagon habe ich eine SMD Variante der Modifikation mit Teilen aus der Restekiste durchgeführt. Im Wesentlichen handelt es sich um die Entfernung des 25MHz Quarzes für die PLL und stattdessen Einspeisung einer externen GPSDO Referenz. Dafür wir der hinterste der F-Ausgänge zu einem Eingang umfunktioniert. Der DC-Zweig wird entfernt und stattdessen der Mittelpin über 2x 10nF auf den Quarzeingang gelegt. Tests bei DL0CRE zeigen, dass das LNB deutlich! frequenzstabiler ist. Die 25MHz wurden dabei über einen LeoBodnar GPSDO erzeugt.

    An den Stellen mit den gelben Kreuzen werden die Leiterbahnen aufgetrennt. An der Stelle 1 habe ich einen 0402 0R Widerstand eingebaut. Bei 2 (0402) und 4 (0805) kommt jeweils ein 10nF Kondensator rein. Bei 3 habe ich einen 1206 100R Widerstand eingelötet, weil kein kleinerer verfügbar war. Nach Modifikation sieht das ganze so aus:

    Das Original mit bedrahteten Bauteilen findet sich unter:'hail-2_LNBs_and_Antennaes#Locking_the_Quad_Octagon_LNB_to_a_25_MHz_Reference

    Wichtig hier ist, dass man tatsächlich die PLL Variante des LNBs erwischt. Es gibt unter der gleichen Bezeichung auf DRO Typen, die hierfür nicht brauchbar sind. Quick and Dirty Guide zur Unterscheidung:

    vy73 de Florian DF2ET