Posts by hb9iiu

    Es tut mir leid, auf Englisch zu posten, aber das System hat mir nicht erlaubt, Englisch auszuwählen (Google Übersetzer)

    I was testing the 1st stage PA of a future DATV station using a Pluto with firmware 0303 followed by the CN0417 RF amp.

    Everthing worked as per expectations until I changed the Gain parameter in the rtmp line setting it (wrongly) to 10 instead as of -10.

    This was done just to see if this parameter would reduce output power as expected.

    Since then, the maximum RF output power I can get out from the Pluto is approx -10 dBm (or approx. +9 dB after the CN0417) applying a 2.4 Ghz CW signal.

    Comparing with my previous measures, this is about 10 dB less than before my trials.

    These 10 dB less do obviously not allow to drive the above mentioned 1st stage PA as it should.

    Same results with another new CN0417, re-flashed firmware, and DATV modulation seems to be ok as I can decode locally in Minitiouner despite of the low power.

    So the Pluto is not bricked, but something must have happened that reduced the Pluto output Power.

    Any advice will be very much appreciated.

    Thank you



    Although I succeeded in activating the external clock input to use the 40 Mhz signal from a Leo Bodnar GPSDO, I am struggling in doing the same for injecting 25 Mhz instead.

    I used the following command:

    fw_setenv ad936x_ext_refclk ‘<25000000>’

    followed by

    fw_setenv xo_correction ‘<25000000>’

    Is this the correct way?

    Second issue

    When using the fw_setenv command, I made a typing mistake in the arguments so that I get the following now when using fw_printenv






    How can I delete the wron entry: ad936x_ext_refclck=<2500000>

    Enjoy the Sunday



    I can stream from OBS to a Nginx based RTMP server on my Jetson Nano 2gb.

    This was rather easy to put in place, but I’m struggling in re-streaming the same after H265 encoding to the Pluto RTMP server using accelerated hardware encoding.

    I am pretty sure that this is possible, and perhaps someone managed to achieve this?

    Many thanks in advance for your advice.

    Kind regards

    73 de HB9IIU

    Reading some recent and old posts on LNB modifications, I decided to break apart an Avenger LNB this morning and modify it to inject 27 Mhz from a Leo Bodnar GPSDO.

    Although somehow locking, I get very strange symmetric patterns on SDR Console, and can even hear lower or upper beacon, but at many different places left and right from the center beacon.

    Must definitely have made something wrong that experts will in all probabilities immediately find out when looking at the below pictures.

    Thank you


    Hello. I already asked the below question in another forum and received the answer that I should first go back to school. but I'm convinced that someone will help me here.

    I know that I have 12-18Vdc in the coax feeding my LNB.

    1) how could i "extract" this DC just before the LNB to supply a GPSDO via a 5V 7405 voltage regulator to allow me injecting the 25 Mhz directly nearby the LNB

    2) alternatively, how could i "convey" the 25Mhz GPSDO signal via the coax cable together with the DC and then "extract" it inside the LNB for the same purpose

    Thank you in advance for all valuable feedback


    Hi David,

    Very interesting, thank you.

    I will do some comparative tests (with, and without tube), but have already decided that final solution will be without tube.

    It was just very practical to wind the coil, but once wound, its rigid enough. I will also try with a different matching system as proposed by George.

    Will post results once available

    73 de HB9IIU


    Dear All

    I just finalised a Helix antenna I printed over the night.

    Pictures are showing the concept, and assembly.

    Everything was almost first time right.

    I could adjust the impedance, but I am not 100% happy about the results.

    I wonder how I can move the 2nd deep to approximately match with 2.4 GHz (now at approx. 2.2).

    Could not attached 3D files as too big, but will share on request.

    Any suggestions would be very much welcome.


    73 de HB9IIU, Daniel

    Many thanks Adrian for your time explaining all this, and George for the excellent links providing also very useful theoretical & practical information.

    My idea is to measure the output power of the Khune PA with an economical AD8318 based RF power meter.

    But I have to be careful and stay focused, because the link of George gave me already some other new project ideas....Hi!

    Have a great weekend


    Thanks Adrian, I think I got the point.

    I should receive a 40 dB directional coupler within next days. Is it possible to build a dummy load by myself for 2.4 GHz ? (like I did for HF by means of a set of parallel resistors)




    Sorry for this novice question.

    How do you measure the effective power output of a PA rated 20 Watts nominal output with an rf power meter able to measure between -55 and -5 dBm.



    Many thanks Johannes

    I actually already have prepared something in this direction, but based on an ESP8266 Wifi Arduino module with RS3232 (3 Volts) level converter. The device is hosting a webpage as shown below (sorry for the WSVR spelling mistake).

    At the moment I am facing 2 issues.

    I get strange values for FWD and REF power (see here :

    Strange results from KUHNE Up-Converter data port)

    Second, the Kuhne is very slow in replying to requests via the serial port so that I will have to program some average filters for the Power and VSWR bar-graphs.

    The webpage is a combination of html, css, and javascripts.

    Have you tried to analyse what the Kuhne sends you back for FWD and REF when transmitting (antenna/dummy load)?

    Kind regards


    Thanks All!

    The Bias-T solution is exactly what I am looking for to avoid additional cables. The issue is, as mentioned by Ed, the admissible RF Power of the common ones found in the market. Difficult to find data, but for the ones I found, they were only able to handle 500mW. Will look around for a DIY solution, or perhaps a small radio remote solution on 433 Mhz.



    Why do you want to do that? The idea is the wanted band is between the two resonances to get good circular polarisation. The response looks fine to me. The highest resonance is at the cut off corners so bending slightly towards the ground plane might work or perhaps a bit of kapton tape.


    Thank you Mike for your post. Good lesson learned!

    Hi Uli

    Just google for 'Simple Spectrum Analyser D6 with Trace Generator'. Its about 50 USD and results so far on other antennas were satisfying. I recommend to use the 'SNA Sharp' software from F4HTQ (simple to use as a starting point).



    Thank you Mike

    Also the manual is clearly stating this requirement, mentioning that it can also be achieved by injecting +3 .....12 VDC to the inner conductor of the IF cable.


    1) I don't want o open my rig to carry out the proposed modification to inject DC; what can I do? (external solution)

    2) what if I leave the Khune constantly in TX while in RX on the receiving side?

    Thank you


    Good morning

    While developing a web interface to read the MKU UP 2424 B status remotely, I noticed something strange in respect to the values returned via the data port for forwarded and reflected powers 0 to 255 range)

    First trials with a Potty antenna resulted in a VSWR > 6 (!)

    I then connected a 50 Ohm dummy load, and it was even worse.

    Up-converter returned 146 for Forward and 94 for Reflected which (if my calculations are correct) would result in a VSWR of 9.1.

    Has anyone experienced the same?, or is there something I do not understand?