Yet another L4B rescue

Discussion in 'Amateur Radio Amplifiers' started by W9JSW, Apr 13, 2018.

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  1. KM1H

    KM1H Ham Member QRZ Page

    The burner transformer since those are often free, the later versions and furnaces run more HV , ~ 14 KV , along with higher pump pressure allowing smaller diameter nozzles (mine is a .6 GPH) for higher efficiency. I upgraded my furnace components about 7 years ago and saved hundreds of $$$ that winter.

    C-F kits arent cheap. In the late 60's, between National Radio, and Sanders Associates, I spent time at High Voltage Engineering in Burlington MA as a Engr Tech building 100 and 250 KV power supplies that were sold to shoe factories; plus to clothes factories to create the permanent press feature which was new at the time. I also spent a short time on the million volt particle accelerator.
    The head was Robert J. Van de Graaff himself, as nice a person as you could get.

    WB1E, K0OKS and KD2ACO like this.
  2. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Or someone cleaned the tubes with any number of cleaners or friction which could have removed the paint...
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Guilty. I did that a couple of times many years ago.

    Many solvents will indeed remove that paint, and some are household items. I sometimes "wash" tubes in the dishwasher (it gets them shiny clean) but the "lemon Cascade" or whatever washes off the markings; I use a permanent marker "Sharpie" to write the tube numbers on the tubes first, now, and the dishwasher detergent does not wash that off.:)
  4. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Is there any documentation about Eimac using heat sensitive paint? I wonder if this isn't a wive's tale.

    Citation needed, or it is false ;)
  5. W9JSW

    W9JSW Ham Member QRZ Page

    Sorry guys. I won't make the net. YXL is quilting and I need to wash my tubes while she is gone...
  6. WB1E

    WB1E Ham Member QRZ Page

    When my ship comes in, I'll buy a vinyl cutter and make and apply a negative decal and quickly bead blast the data back onto the tube forever. The tubes I buy take a single wipe or even touch and all the ink is gone. So that is why my tubes stay dirty until I use them.
    KD2ACO likes this.
  7. N8FVJ

    N8FVJ Ham Member QRZ Page

    I am not sure, but the Drake L4B matching network is designed for 2500 volts where as at 1200 volts the amp may not providing matching on 75 meters. I think there is a L7 power supply for sale on QTH. L7 is about the same as an L4B power supply.
  8. W9JSW

    W9JSW Ham Member QRZ Page

    This is an old thread. What I did is build a supply using a large Antek transformer and Harbach PS board. Makes 2800V and supplies the amp nicely. I built it in a Hammond case that looks a lot like the OEM one. Used a cinch connector as well. There was a guy on the bay that sold the OEM multi conductor cable. It all turned out real nice.
  9. W1QJ

    W1QJ Ham Member QRZ Page

    John, It wasn't until you made this post that I realized it was you. The thought never occurred to me until you mentioned you built the L4 power supply with the Antek torroid transformer. That and the original case that yes indeed looks like the original. Lou
  10. W9JSW

    W9JSW Ham Member QRZ Page

    Some pics

    Almost finished. Just had to add the HV fuse.


    In process...


    Schematic. One change is I just used one of the 2 lines from the LV/HV switch.


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