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First homebrew transciever - not working

Discussion in 'Homebrew and Kit Projects' started by S52Y, Dec 28, 2016.

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  1. S52Y

    S52Y Ham Member QRZ Page

    Oh Mark i really cant thank you enough for all your help!

    I had it wired as vk3ye and aa7ee with no luck.

    I have checked the lm386 datasheet and those points that you pointed out. I had wires twisted to the speaker but didnt have them twisted to the lm386 chip itself.

    Today i will go buy a new lm386 (maybe this one is defective or maybe i have blown it), and solder everything on a pcb.

    Also i will try to re-cut all the allready made pcbs and solder them together as compact as i can.


    K6BSU, yes Mark is really amazing..My project would probably on the unfinished projects shelf if it wasnt for him :)

    I have really learned a lot over this thread.


    Anyway, i will get back to you guys with the results.


    73, pampi
     
  2. S52Y

    S52Y Ham Member QRZ Page

    Well ok. A little progress.

    I have soldered everything as compact as i can and i could still hear the motorboating..BUT, when i was messing around i have put my hand few centimeters above the LM386 and the motorboating stopped. Hmm? So i have put a box over the LM386 and now there is no motorboating. YEY. There was probably interference from the oscillator or some other electronics in my shack. So the previous bredboard configuration probably wasnt the problem becuse the audio is still so low that even if i use headphones i can hear talking but cant understand anything. Ok, the propagations werent so great but i could hear some guy on my HF rig at about 57 and quickly turned on the micro 40 and i could hear him, but so faintly that i couldnt understand a word.

    Could the problem be at the buffer stage?
    I was a little sceptical about the wiring around the MPF102.

    I also tried to make 2 LM386 in series, one with original wiring as schematics, and the other at about 20db gain with no improvement.
     
  3. N7EKU

    N7EKU Ham Member QRZ Page

    Hi Pampi,

    I might have some free time this coming week to try and build this myself. If I do, I will let you know. That way I can get an idea of how sensitive the set is, and I can also make some measurements using a homebrew diode RF probe so that you can do the same measurements on your end. How does that sound?

    Cheers and 73,


    Mark.
     
    VK4FFAB likes this.
  4. S52Y

    S52Y Ham Member QRZ Page

    Oh Mark, that would be great but, i really cant ask you to do that.. to spend your time and money on this..

    i dont know even what to say...

    73 pampi
     
  5. N7EKU

    N7EKU Ham Member QRZ Page

    Hi,

    Oh, I have enough parts already, and it will be fun to see how it turns out! It just depends on how much time I have.

    Cheers,


    Mark.
     
  6. S52Y

    S52Y Ham Member QRZ Page

    Well ok then Mark that would be awesome!

    Im waiting on your info :)

    I have also re-cutted the pcb's and soldered them together so the components arent so far apart.
    I have also replaced the 100uh choke with a normal one..(the one that looks like a resistor).

    Sadly it still isnt working..

    73 pampi
     
  7. N7EKU

    N7EKU Ham Member QRZ Page

    Hi Pampi,

    OK, I will start first with the audio amp. I'm going to use the configuration from the data sheet for the "am radio".

    I will put the mixer circuit on the same PCB piece, and the oscillator on its own board.
    I will post a picture of the parts and a rough layout for the audio section later (it's not working with my phone now).

    73


    Mark
     
  8. S52Y

    S52Y Ham Member QRZ Page

    Hey Mark. Ok, thats great to hear!

    Ill be waiting on your info!

    Thanks again!
     
  9. N7EKU

    N7EKU Ham Member QRZ Page

    Hi Pampi,

    I had time to build up the amp section this weekend. Rather than post it here, I will put it up on my website as it will be easier to keep organized and to view there. I'll try to get it posted tomorrow evening and will let you know. So far, the amp works very well running my mp3 player, with no signs of instability and no hiss or noise problems (of course the real test is yet to come).

    Cheers and 73,


    Mark.
     
    S52Y and VK4FFAB like this.
  10. VK4FFAB

    VK4FFAB Ham Member QRZ Page

    Good on you Mark, awesome work going above and beyond the call of duty to be helpful.
     
    S52Y likes this.

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