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SB-220 Find

Discussion in 'Amateur Radio Amplifiers' started by AF6LJ, Dec 19, 2012.

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  1. W1BR

    W1BR Ham Member QRZ Page

    I'm going deaf! I don't hear my fan....

    Did you try the shroud modification? That looks to be worthwhile. I wish I did it when my amp was back in "kit form."
     
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    The shroud modification will be coming soon, I picked some material today along with some decent Teflon wire.

    The Junque store that Pat frequents has a really good selection of wire, among other things.
     
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    Mouser parts order started....
    W7RY soft start board received and partially stuffed.
    Stay Tuned...........
     
  4. WA7PRC

    WA7PRC Ham Member QRZ Page

    Groovy. Did you win the auction on the vacuum relays that I mentioned a while back?
     
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    No I did not...
    That's okay all things come in good time. :)
     
  6. AF6LJ

    AF6LJ Ham Member QRZ Page

    Here is the soft start board I'm using in my SB-220, this board is a W7RY design. I chose this board over other designs because of the ease of which it can be changed from one line voltage to another.
    [​IMG]

    Stay tuned....
     
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    Excellent. I made progress on my GS-35b 160m amplifier. After rewinding
    my plate xfmr, I finally have it varnish (Dolph's CC-1305 polyester resin)
    impregnated:

    [​IMG] [​IMG]

    I'll use a full wave doubler. At 240V supply, the taps will yield no-load
    HV = 3340/3580/3830/4075 VDC out of the rectifier. Secondary DCR = 6Ω.

    Today, the mail carrier brought a few parts to use on the primary side.
    I've settled on the WD7S "all in one" triode control board.
    Progress continues to gallop along at its usual snail's pace. ;)
     
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    That looks sweet.

    No solder smoke today, I had yard work to do.......

    Plans for Oscar to get the first of the modifications are on for early next week.
     
  9. AF6LJ

    AF6LJ Ham Member QRZ Page

    I spent the weekend looking around here for my stash of scrap copper sheet.
    I found it and made a terminal for the top of my newly acquired RF parts plate choke.
    The reason this has not gone in sooner is mainly due to my debating the location of said choke.
    After fabracating the terminal and installing it atop the plate choke it was time to take Oscar out of line and do a little disassembly.
    [​IMG]
    This is where I decided the choke was going to go...

    This image is with the choke installed and clocked into the proper position along with the plate connector properly clocked.....

    [​IMG]

    A minor adjustment had to be made, but not a problem.
    The hole for the choke had to be drilled and the hole for the doorknob cap is an existing hole left over from the one-sixty mod.

    Here are two views of the result, seems like every time you do something in the RF deck the tune cap has to come out.
    And for those who would consider this mod the plate choke clears the RF shield cover by just under a half inch, which is good enough.
    [​IMG]

    [​IMG]
    Some prep work needs to be done before the soft start can go in.
    I know where I would like to put it however that requires a lot of dissassembly, so I may settle for a different location.

    Stay Tuned..............
     
  10. WA7PRC

    WA7PRC Ham Member QRZ Page

    It looks pretty good, Sue. The cooling fan blade is supposed to be centered on the hole in the panel (it looks like it's offset toward the toobs). I expect it won't matter much if you add a shroud like David K5DBX suggests here. He used 1/16" material. I used some soft 0.030" thick stock from the box store (it cuts easily with scissors). Two beads of noncorrosive RTV secures the middle of the top piece to the shield panel above the fan blade. My SB220 is waiting for me to get off my gluteous maximus and finish the other modifications.

    Now that the plate transformer for my 160m GS35b 'amplefire' project is ready, I've started on building the HV power supply. Sheet aluminum for the chassis is on the way.
     
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