6 band transciever kit and 45W PA

Discussion in 'Homebrew and Kit Projects' started by WA6MHZ, Dec 6, 2017.

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  1. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    So a very good friend passed me this as a very kind present and I was tickled to get it. I have been watching these for a long time and fancied building one. There is lotsa SMT parts which doesn't scare me in the slightest as I am a professional SMT RF ENGINEERING TECH. I work with the stuff all day long. He also threw in the nice DDS boards

    Documentation for this is really sketchy and it is unknown if it will work, but it is fun to build even if it doesnt work!

    So I started to build the board and things went well until we got to the WIND THE COILS section. Then it got scary.

    I did a few coils and tossed the project back in the box.

    next I went after the power amp part of it.
    Things got ugly at that point. It turns out the Power Amp is very haphazardly designed and there are multiple discrepancies in the procedure.

    One glaring gotcha is in the part where they tell you to wind this T2 Transformer.
    WIND 6 turns on the primary
    NO its 4 turns!!!
    NO IT IS SIX!!!!
    NO Its 5 turns!!!!!!
    If you wind it 4 turns you will blow it up!!
    WELL WTF IS IT??? HOW MANY &^*^*^*^*#$#(*(&( TURNS do I wind????

    There is a blurry schematic and it shows R4 as a 20 OHM. The BOM and procedure tell you its a 5.6 OHm!!! But they only gave you two 5.6 ohm resistors and those are for R6 and R7!!!
    They left off the BOM R15 and R9 entirely!!! Luckily I have a well equipped stockroom that has those parts. I had to use a 605 size though, not 805 sized 510 Ohms in stock.

    But that wasn't the worst of it.

    They said when U turn it on it is supposed to draw only 200 mA, Mine was drawing 950 mA and Q2 was getting hot.
    they say you are supposed to read .9VDC a the emitter of Q2. Mine was reading 4.5V!!!!

    I took out the Q2 and measured it on a VOM and then a transistor tester. Tests good.
    SO WTF?? All other circuits were checked and all was fine. No it seems the Kitter put in a BOGUS 2SC1971!!!! It is counterfit, even though it is labled C1971 as it should be with the Mitsubushi logo!

    Chinese companies are doing that alot lately!!
    THey will take some cheap transistor, silk screen a bogus Part number on it and sell it as the part you want.

    That happened with some ICOM IC746 I tried to fix for a friend. I bought some replacement driver transistors off of EBAY from China, but they were COUNTERFIT and didn't work at all!!

    There are many of these 6 band kits from China on Ebay. Here is an example

    Here is one of the 45 W power amps

    this one is only $16!!

    Anyone ever make one of these that actually worked??
  2. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    no one else in the world has successfully built one of these???
  3. KD1JV

    KD1JV Ham Member QRZ Page

    I've been tempted to buy one of the 45W kits for $16 just to see if it actually does work. I have my doubts. If it doesn't, it might have $16 worth of useable parts to build one which does.
    N2EY likes this.
  4. VK2HHS

    VK2HHS Ham Member QRZ Page

    You might consider looking at some of the Chinese kit offerings from a few years ago.

    Often many of these kits share a common genesis from which they're all copied ad nauseam ....

    Eaxmple: BA6BF KN-Q10

  5. VK4HAT

    VK4HAT XML Subscriber QRZ Page

    Built the 45w amp, worked perfectly. 2SC1971 has been unobtanium for over 10 years. The kit I got had a 2nd hand tranny in it, pulled from a board. Futurlec have a lot of new old stock, try a 2sc5771 and rebias to suit. FT of 200mhz, you can then replace the final fets with rd16hhf1 and have fairly flat gain to 10m and 12v operation.
    N2EY likes this.
  6. KH2BR

    KH2BR Ham Member QRZ Page

    OK, HERE ya Go !!!------------------------.>>>>>

    The builders group is on Facebook.
    When you put the transformers in, just lightly tack the connections so you can remove them if you have to.
    I'm starting my second one because I destroyed the pcb by trying to remove and replace transformers.
  7. K0MB

    K0MB XML Subscriber QRZ Page

    Say, Mr Pro-Tech service guy- How'd your Heathkit QRP build finally turn out?
    N2EY likes this.

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