Posts by hb9iiu

    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?