New PA stage for good old ATLAS 350XL radio

Discussion in 'Homebrew and Kit Projects' started by YU1OXB, May 6, 2015.

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  1. KC7NOA

    KC7NOA Ham Member QRZ Page

    Im hoping to move the Bias onto the same board as the finals ... and/or change to Fet's like the previously mentioned Rd70's or 100 ...

    Iv got terrible feedback for some reason and i suspect its in part to the driver/pre in teh same compartment as the mixing PC250
     
  2. YU1OXB

    YU1OXB Ham Member QRZ Page

    What format of PCB design file it should be... my software for PCB design can export PDF in 4000dpi max or Gerber (HPGL).
     
  3. W9GB

    W9GB Ham Member QRZ Page

  4. KC7NOA

    KC7NOA Ham Member QRZ Page

    Im looking to get a board done with the SD1487 design .... I have some MRF454's to use ...
     
  5. YU1OXB

    YU1OXB Ham Member QRZ Page

    As I promised, here are files for alternative PA PCB for Atlas 350XL.

    Apart from 5 mounting holes and cutouts for transistors , there are no holes to drill on a board. I designed this board so that all components are to be soldered on a top layer tracks. That way it is much easier to change or replace components. Bottom layer is whole copper and without tracks. There are numerous plated through-holes between top ground surfaces and a bottom layer which will enhance grounding and overall stability.

    Board is designed for RF transistors in a .500” 4L Flange case (outputs) and .380” 4L Flange case for driver. Many RF transistors are in those cases so board is not just for one or two types. My Atlas now have SD1487 as outputs and SD1285 as sriver. Please note that if you are going to use different transistors, some components might need slight change of values.

    [​IMG]
     

    Attached Files:

    KV4PD and KG7SWP like this.
  6. KC7NOA

    KC7NOA Ham Member QRZ Page

    Thank you for posting the design ....

    New question, did you leave PC540/530 intact and just remove the bias or did you go with more intensive modifications?
     
  7. YU1OXB

    YU1OXB Ham Member QRZ Page

    You have to make some mods on PC-530 and this is what I've done.

    [​IMG]

    You can use 2N5490 instead of my BD243 but I just left it as is.
    *** I also have Gerber files for that new board but I don't know how to attach them here. If anyone needs them for professional production, I can send in Email - or teach me how to post them here!?
     
    Last edited: Jun 19, 2016
  8. YU1OXB

    YU1OXB Ham Member QRZ Page

    ... and a schematic.

    [​IMG]

    I forgot to highlight one more thing - I have a small 12V/2A PCB type relay which I added later for switching on supply for driver stage and BIAS block only on transmit. Colectors of output devices are permanently on +14V.
     
  9. AI6NA

    AI6NA Ham Member QRZ Page

    Have you updated your design, and is the radio still in use.
    Jonathan AI6NA
     
  10. W9GB

    W9GB Ham Member QRZ Page

    As suggested 18 months ago, submit your Design and Gerber to OSH Park.
    This is a community of printed circuit board (PCB) designs and shared projects.
    https://oshpark.com/
    They take designs from lots of people, put them all together on a panel and reduce costs for amateur and hobbyist builders by combining orders to a panel sent to fabricator.
     

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