Posts by s21rc

    Hi Artur,
    Happy new year. I am planning to replace the 2x hackRF One boards I used for qo-100 NB with an adalm Pluto I got (Enclosure says Rev C, PCB inside says Rev D).

    Apart from the GPSDO solution (I am not planning to buy a Leo Bodnar GPSDO at this point and already have one DIY GPSDO with 10MHz OCXO) what is the best and easy solution for NB operation?

    10MHz OCXO >> NB3N3020 (in x4)?

    ** I have searched the forums for few days, and apparently couldn't find the exact information.

    Please suggest.

    Sorry for the photo - here is the full one.
    And Thanks all for confirming that it is ok. Today spent 8 hours to make a small cavity filter for 2400Mhz as my BPF is still in transit and do not know when it will arrive - BUT failed.

    Hello All,
    Need another help again. I have made the following antenna following DC8PAT's design. Instead of copper plate I have used double side CCB.

    The tuning vane/capacitor almost had to bend opposite side to get 2400Mhz tuned. Is this a problem for the signal polarization?

    Fazlay/ S21RC

    Dear All,
    I need help from you the experts who have already done this many times. (I do my reading/searching and only post when I can't get it or understand it. so please bare with me.)

    Two help needed:
    1. TX Antenna made and tested - following DC8PAT 's design (his 3D files are big help) - attaching is a picture of the capacitor match and the VNA graph. Please advise if it's ok? I am concern about the tuning capacitor plate - to bring the antenna to 2400Mhz It went the other way compared to picture of other users.

    2. I have the TX SDR (0.5ppm TCXO), LNA [extra one unit ready if needed], PA 8W [optional 2W for test], Helix antenna with bulls Eye TCXO LNB. Missing is the BPF (lost in transit :p ). Instead of waiting for the BPF can anyone give me a microstrip PCB layout so that I can eatch and scrap with knife to tune at 2400MHz Fc? (Please do not advise SAW filter module - that will take another 2 months to arrive If I order today)

    Cavity will be difficult for me as machining/milling is difficult for me here.

    Waiting for your valuable feedback.

    Thanks, Fazlay S21RC


    you might consider feeding the 25MHz over the coax to the lnb, preferably from your shack. A tcxo built in the lnb will drift with temperature changes. Thus it is smart to have the tcxo in a place with minor temp changes. Furthermore, this leaves room for later improvement, like making the tcxo adjustable or feeding an odd frequency derived from the tcxo.

    73, Martin

    Thanks Martin, haven't thought about the drift due to external temperature changes.

    Here is the rough list I have in mind:

    1. RX with ordinary LNB while waiting for TCXO [Done]
    2. TX antenna [in progress]
    3. 10MHz reference for RX/TX SDR from OCXO 10MHz [in progress]
    4. Doing TX test [waiting for SDR to arrive]
    5. Improving stability - making a GPSDO with OCXO

    6. Making a 25MHz clock from the GPSDO/OCXO using si5351 and a bandpass filter.

    Any advise is always welcome and appreciated.

    Thanks, 73, S21RC

    Hi Geert,
    I will surely listen to the JOTA station on QO-100 (no TX capability yet). I was control operator for many jota station (S21SHQ) in the past, maybe in future someday I can pursue Bangladesh Scouts to again to try JOTA again and not rely on JOTI and Echolink :)

    73, Fazlay/S21RC

    And do so with the PCB out of the casing (mind the antenna pins - ESD sensitive!)

    If you try this with the PCB still in the case you will find that the casing cools enough that the solder won't melt.

    This PCB material is a pretty good heat conductor.

    And keep in mind that leaded solder has a lower melting point. So you can "wet" the pads with old solder to mix old with new to reduce the melting temperature.

    Thanks, I am waiting for the 25Mhz TCXO to arrive from PRC. Once I get those I will try to replace the stock Xtal. In the meanwhile a bullseye LNB arrived which I ordered last month. Will put the BullsEye to see how much improves.

    ** Antenna installed, already can receive the QO-100 using a 60cm TV dish with unmodified LNB.

    73, S21RC

    Hello all,
    Greetings. I need help to make an 10MHz ref clock for HackRF-one SDR(TX radio).

    Today salvaged one Vectron (C4710C1-0023 10.000000MHz 12700-01371 0737) OCXO from a broken VSAT modem main board. It has 5 pin:

    1: EFC - Electronic Frequency Control input
    2: Reference voltage output
    3: RF Out
    4: GND
    5: Vs

    Here is the datasheet:
    (I cant find if it is HCMOS or Sinewave out from the part numbers.)

    This is my first time playing with an OCXO - so not clear how to use this. From different project by other hams I think I need to put Vs (12V), and set the EFC to 2.5v(or should i make it 0 by connecting to gnd?) derived from the reference voltage output using a multiturn potentiometer. Please advise if I am correct?

    Thanks, S21RC

    60cm DTH offset antenna, unmodified 25MHz Xtal LNB - SDR Console locked to beacon.

    Receive S9++ signal from my location (NL53er, elevation 14.9 degree). Monitored some station. Very clean signal (Leila was activating too frequently).

    Now waiting for the TX parts and TCXO to arrive. Meanwhile will make the Helix antenna and keep it ready.

    73, S21RC


    Just melt enough solder on it to make it really hot. It will swim on the solder at some point. Then use pliers to pick it up and remove it.

    73, Martin

    Thanks Martin, I have hot air soldering station - but there are so many parts nearby I might melt those as well :p

    Sure will try to remove it and put an external 25MHz reference - maybe I will be successful after few try (good that they are not expensive).

    Thanks, 73, fazlay

    Thanks George,
    I have ordered two SPF5189 so can play with it as you suggested. Waiting for all the modules to arrive, it's been shipped from China.

    ** I do not have Spectrum Analyzer or 2.4GHz Power meter - so difficult for me to measure gain/attenuation. Best I can do is make the diagram as much full proof as possible with enough margin not to distort output but able to reach the bird.

    Meanwhile will install the RX part and also TX cabling this week and update you all.

    Thanks again for the help.

    73, s21rc

    Hello all,
    Today I have opened a 3$ DTH TV LNB. Some detail if anyone needed.

    DTH Provider: AKASH DTH (Bangladesh)
    LNB Make: Inverto
    Model: SN411-OOPRO-OPN
    XTAL: 25.00MHz

    Here are the PCB and shell photo. The Xtal looks so small and delicate, I don't think I can remove it without hurting the PCB.

    73, S21RC

    Hi George,
    Thanks for pointing it out, I have tried to do the link budget as best I could (this is my first system which will be above 70cm) - there might be error.

    Can you please check if this should work (I am confuse, in this site it said minimum PEP is 10W for SSB/NB, does PEP and EIRP same?)

    Clarification: If both the 8w wifi PA and SPF5189z has 12dB gain, then why use the PA and not another SPF5189?

    Thanks a lot in advance, Fazlay/S21RC

    Hello all,
    Here is the plan for my setup. I am concern about the following two issue:

    1. The 15m run of coaxial in the TX chain. Can you advise if this would work? It is difficult for me to put much equipment at the antenna site (i.e. remote SDR using a small RaspPi/OrangePi).

    The cable is similar to LMR400, and attenuation would be around 3.3 + some more due to the N-SMA pigtail.

    2. Tapping DC power from the RX cable, faltering with inductor and using a regulator for the TX driver and PA.
    Or: is it better to insert the DC power in the TX cable?

    Please advise.
    Thanks in advance, 73, S21RC

    Thanks a lot Sandro. That's good news for me. I like your hotel setup :p I am sure you had a "NO DISTRUB" sign hanged on the door the whole time you were there :D

    Hello OM,
    Greetings from Bangladesh. I have been gathering as much info I get about activating QO-100 - very interesting, I have the following two questions, can anyone please advise:

    1: Minimum Antenna dish size for receiving QO-100? (off the self Ku Band 80cm DTH antenna would be easy to stealth as DTH).

    Info: From my location the antenna elevation angel is 15 degree - almost at the boarder of sat footprint. Please see attached.

    2. SDR or Icom UHF radio (by modifying LNB PLL frequency)? Which one would give better receive?

    My plan is to RX first, if all works then will work with TX.

    Thanks in advance, 73, Fazlay, S21RC