Hilfe mit Mikro SWR Meter

    Hallo, Speaky-Speziallisten!


    I have just added the "Mikro SWR Meter" to my Speaky but it gives "strange" readings and I am a bit lost with this issue.


    Is there anyone who has experience with this SWR Meter and could give some advice or tips regarding mounting...? I would be grateful...


    1-I have the Emtec Z-Match. When I adjust for low SWR on the Z-Match, the Mikro SWR is light green, but if I increase power, the led goes to red.


    2-With a homebrew dummy load (carbon resistors) same result.


    3-I installed the kit directly (the three waffers) at the output socket. The led on the front panel, the three wires twisted, color coded.


    I've checked the wires against the schematics a couple of times.


    At the moment I have only a mobile 40m antenna from WiMo, in house, using a heating radiator as ground plane -I'm just beginning :)


    Any comment? :)


    Regards

    73 de
    Félix
    ec2alv


    Felix,
    I never before have heard about such a problem, but your installation differs from what we do.
    Install the 3colour LED directly to the small PCB and mount it where you want. The small PCB is fixed only by the LED.
    Install the 50 Ohm head between lowpassfilter output and antenna connecor.
    Use the twisted wire between both PCB´s


    Now try again.

    73/2 de Peter, DL2FI
    Proud member of Second Class Operators Club SOC and Flying Pig Zapper #OOO (Certificated Kit Destroyer)

    Vielen dank, Peter, für deine Antwort.


    I will change the location of the SWR Board as per your comments. (maybe too much RF is driving the transistors...?)


    Will let know results.


    Regards,

    73 de
    Félix
    ec2alv

    Hello Felix,


    check again your wiring between the two PCBs... if you interchange them, you will get exactly your behavior. I know it, because it happened to me ;)

    vy 73/72 de Uwe, DL4AC
    www.dl4ac.de

    Einmal editiert, zuletzt von DL4AC ()

    Thanks, Uwe, for your comments,


    I have already moved the Anzeige PIB to the front panel, following Peter's advice.
    Same thing.


    Then, following your advice, I interchanged the two wires from the MessKopf to the Anzeige, and the LED didn't lit at all (!!!!). Changed them back again.


    I rechecked the wiring again as per the manuals:


    wire from MessKopf nº 5 to Anzeige outermost conn. (marked Reflected)
    wire from MessKopf nº 6 to Anzeige middle conn. (marked Forward)
    LED: lead nearest to flat border to conn. nearest PIB lettering.


    Well, the ZM-2 is telling me I got a match (LED off) and the Mikro tells me I don't...


    I think next thing I do is go to the Club this Friday evening and check both the ZM-2 and the Mikro SWR against a known working antenna system...


    I also made some resistance readings (also diode check) on the Messkopf and found nothing wrong.


    The Anzeige's discrete components differ from the schematic somewhat, but I take for granted that the supplied ones are the correct ones.


    Well, this is my thinking. Not too much to do, I guess. I must admit that I'm a bit baffled with this issue. Of course, any idea will be very welcome :)


    Vielen dank für Deine Hilfe,

    73 de
    Félix
    ec2alv

    Hi Felix,


    in your situation I would make sure at first the SWR probe (Messkopf) is working standalone as it should. Take any desktop - meter and check the output at the two wires against ground . Using a 51 OHm resistor load -- you should read a very small value and a very much higher one. Absolute values don't matter here.
    Now you can be sure not to mess up the two wires (provided the same direction of feeding the probe with RF)
    I had a similar problem. I fixed it by removing some solder from one of the transistor- arrays. :)
    Anyway it is better to prove the function of the complete unit with the dummy load at first because you would have a well defined environment then.
    The micro SWR probe is very sensitive.


    72s


    Lutz, DL2HRP

    Lutz, thank you very much for your "tip". It proved valuable.


    I did as per your instructions and the Messkopf behaved as you predicted and was expected:


    a High reading (about 1,5-1,7 volts) at pin 6 (forward) and negligible reading at pin 5 (reflected). I did the readings at low power (pwr. pot. at about 1/3).


    So we can discard the Messkopf.


    Next I connected only one wire to the Anzeige: Forward signal, pin 6 to pin marked "forward" on the Anzeige:


    the LED lit with a light orange color!


    Next I connected this wire to the pin marked "reflected" on the Anzeige:


    the LED didn't light up (I expected to see a green light)


    At this point I can deduct, if I got it right, that I got two issues here:


    1- A reverse connected LED (though the lead next to the flattened side of the LED is connected to the BC807)


    2- A circuit malfunction (the reflected circuit)


    If you agree with what I have said here, I will forward on this issue to Peter to see what can be done here.


    Noch einmal, vielen Dank, Lutz, für Deine Hilfe :)


    Félix

    73 de
    Félix
    ec2alv

    Hi again Felix,


    Nice to hear that the SWR probe is working well . Now it's time to get a very bright light and a good magnifying glass to look for soldering issues. If you could rule out messed up resistors, please look for soldering issues now. Let me pass a tip from Steven - "Mr. Melt Solder" kd1jv : The best magnifying glass is a digital camera. Make a photo with macro mode enabled using the highest resolution possible and look at it on your monitor.
    Furthermore look if all voltage values at the transitor arrays are sane. A fault may show up as equal values at pads that should not be connected.
    This way I found my fault. You may take a good piece of desolder wick as well and remove some solder at the transistor- arrays. there is enough solder left between the pad an the PCB to provide sufficient connection. This measure alone helped in my case.


    72, Lutz
    DL2HRP

    Hi, Lutz,


    OK, I will follow these new instructions (very nice set of instructions!) this weekend. Will let you know results.


    Regds.
    Félix

    73 de
    Félix
    ec2alv

    Good evening, Lutz,


    let me comment my findings so far:


    1- I looked up for wrong resistors, etc. Found all OK as per photographs in the manual. Also, resistance readings within limits.


    2- Inspected PIB with magnifier glass and backlighted. No solder blobs nor shorts found (as expected, as this PIB's SMDs were mounted by Nikolei, who did me that favor for which I'm very grateful).


    3- Checked for voltages (input pins 5 and 6 disconnected) and found a difference:
    pin 6 (Fwd) reads +0,089 V; pin 5 (Rev) reads 0,000 V.


    4- Applied +1,5 V to pin 6: LED lit full orange color. Applied +1,5 V to pin 5: LED unlit.


    (at this point the LED was turned around, step 4 repeated and then the color was green)


    So, my conclusion is that the Reflected Power amplifier is faulty.


    If you all agree with my thinking, then I will have to look for a replacement BC847


    Thank you for helping me out on this issue :)


    Regards,

    73 de
    Félix
    ec2alv

    Good Morning Felix,


    ....We are getting getting closer to it ;)


    The value reading at pin 5 should not happen. (0V) There should be a steady small current flowing though the 22k resistor which is forming the input terminal 5. This current gives a small voltage drop at this resistor of about 0,046V. (calculated by thumb, -not- measured!!) Your value at pin 6 is abt. double but it is in the right region.
    Now please look for breaks in general - may it be bad joints at the BC847 Array or a faint gap on the PCB. It is silly , but please check if (Rev) Terminal is not shorted to ground. Of course it could be a defective Array but IMHO that's not likely as they are very sturdy.
    Don't rest until this little current flows .... :)
    Unfortunately mine is not ready to work at the moment because I disassembled my ATS-3 TRX for major changes where it is part of. But when it's getting more difficult - I will set it up and provide voltage values for all interesting points.


    We will work it out....
    Good luck!


    72


    Lutz

    Good evening Lutz,


    Good news! It works!


    Finally I found a short that ruined the Reflected input xistor polarization. Now it works as expected =)


    I must thank you for guiding my troubleshooting in a very professional manner. I had already forgotten the good all days when we ough to pin-point the faulty component. Nowadays cost-saving board-swapping is the usual practice but that way of doing things leads to a "rusted" mind.


    Thank you for your help.


    Regards,
    Félix

    73 de
    Félix
    ec2alv


    You are not allone, Felix, 90% of faults I find in QRP rigs are either solder shorts or unsoldered leads ;(

    73/2 de Peter, DL2FI
    Proud member of Second Class Operators Club SOC and Flying Pig Zapper #OOO (Certificated Kit Destroyer)

    Hallo Peter DL 2 FI


    Ich bin dabei das Micro SWR Meter zusammenzubauen


    eine Frage :


    Auf der Seite 5 mit den Bestückungen der Anzeigeplatine ist auf der rechten Platine
    oben links der Spannungswert 10.15 Volt eingetragen. Wie exact muß dieser sein,
    oder sollte da 10 - 15 Volt stehen?


    Ich mal gespannt ob dat Ding läuft. So kleine Krümel von Transistoren habe ich noch
    nie verbaut! Trotz Lupe ist es eine Schinderei so was einzubauen!


    Ich vermisste dich in Friederichshafen. Auf jeden Fall gute Besserung.


    73 DC 0 KA Peter


    Oh jeh, Peter, ein Tuppfahler. Muss natürlich 10-15 V heissen. Ich korrigiere gleich die Baumappe.
    Nu stell dich nich so an, die Dinger sind doch gar nicht so klein :]
    QRO kann jeder, hier wirste endlich mal gefordert :D

    73/2 de Peter, DL2FI
    Proud member of Second Class Operators Club SOC and Flying Pig Zapper #OOO (Certificated Kit Destroyer)