A remote Power Supply for the SB-220

Discussion in 'Amateur Radio Amplifiers' started by WA6MHZ, Apr 26, 2017.

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  1. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    Finally we have some SUCCESS!!
    after great amounts of Hair Tearing, it was discovered the 2N4401 was not being properly driven in the Manual mode. So the relay was torn out and a DPDT relay installed. now we do the same trick as we did with the MPS-A13. Drive the base with a CD4011 inverter through a 1K resistor
    LOTSA Wirewrap wire
    20170720_100458.jpg
    and our revised schematic
    20170720_102220.jpg
    the LUNAR under Test, driven with the IC-575H. Meter on the right is on 20W range. Left meter is 200W range
    20170720_101058.jpg
    OK now we will label the changes on the switch and extra jack
    20170720_105239.jpg
     
    Last edited: Jul 20, 2017
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    Good Deal...
    Looks like all is well.
     
  3. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    It will be put into service tonight, just in case there is a band openning we will still have 100W!
     
    AF6LJ likes this.
  4. AF6LJ

    AF6LJ Ham Member QRZ Page

    We might have to do some testing.
     
  5. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    The Safety choke has been installed along with the tubes, so we are ready to go for Saturday morning when Sue gets here.
     
    KV6O likes this.
  6. AF6LJ

    AF6LJ Ham Member QRZ Page

    That sounds good, if you tune up with the string of dits you can see the peak power on your meter.
    I noticed that meter had a peak reading function. You won't bet as much line voltage sag and power fall off.
     
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    And then, when using SSB, advance the LOAD control and adjust drive until flat-topping on your monitor 'scope goes away. Or, just leave it alone and wait for the "you're as broad as a barn door" complaints. ;)
     
    AF6LJ likes this.
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    He knows the advance the load a little, as for overdriving that amp with a hundred watts, it's not likely to happen.
    :)
     
  9. WA7PRC

    WA7PRC Ham Member QRZ Page

    An inexpensive and easy to use monitor scope will tell you for certain how far to advance the LOAD control and if you're hitting the drive too hard (or not hard enough).

    A used analog scope with 100 MHz BW would work FB at 6m, for about $1/MHz. If you look around a bit, less than that. :)
     
    AF6LJ likes this.
  10. AF6LJ

    AF6LJ Ham Member QRZ Page

    I did that for quite a while here and got my settings down, as long as there are no drastic changes I am good to go .
     

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