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Yaesu FL-2100B Plate Choke Rewind

Discussion in 'Amateur Radio Amplifiers' started by N8VIL, Oct 21, 2015.

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  1. N8VIL

    N8VIL Ham Member QRZ Page

    I recently acquired a Yaesu FL-2100B amplifier that I am in the process of restoring. The plate choke is burnt on the 3rd section from the blocking capacitor. I am going to attempt to rewind the choke and need to know the gauge and type of wire that should be used. Any info and tips on attempting this would be appreciated.

    Sean Davis
    Last edited: Oct 21, 2015
  2. W1QJ

    W1QJ Ham Member QRZ Page

    Hopefully you will make a diagram of the original windings and spacing which is hard enough to do. Then you will have to mic up the wire to see what gauge it is unless someone already knows for sure. The type of wire is the simple part of the project. The wire type is magnet type wire enamel coated and is readily available. Many people who wind chokes find it easy when the core is chucked in a lathe. Good Luck and let us know how you make out.
  3. N8VIL

    N8VIL Ham Member QRZ Page

    I already made a diagram using a machinist ruler (little 6 inch metal ruler) and counted the turns for each section. I am thinking about winding one section at a time and gluing in place. I think this will allow me to wind each subsequent winding without messing up the previous winding. Maybee a little time consuming but I am not in a hurry. I have been searching the internet and cannot find any information on the gauge of the wire needed. The amp was a freebie. It must have been used by a CB'er as it had a RF sensing keying circuit installed and I removed it (whoever did it did a professional looking job). 10 meter tap on tank was moved over 1 coil turn for resonance on 11 meter (put back to original location). I did the bias voltage modification, higher rated rectifiers (none were bad), and new caps. Other than that it is in pristine condition. Not a mark on the bandswitch and looks like new. I have one NOS Cetron tube and I am looking for another NOS Cetron for it. Hopefully someone will chime in as to the wire gauge needed.
  4. W1GCI

    W1GCI Ham Member QRZ Page

    If you know the length of a segment and the number of turns, you can easily get the "turns per inch" with basic math. Going to the copper wire tables in the ARRL handbook should then tell you the gauge for close-wound enamel wire.
  5. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    I too picked one up about a year ago in pristine condition. Not a spec of dust inside or out. Original Cetron tubes as well. I replaced the caps, resistors, diodes, did the bias mod and replaced the clunky relay with much quieter ones. Added LED lighting to the meters to dress it up a bit. It still puts out 600W easy. Not bad for $0.66 / watt.
  6. N8VIL

    N8VIL Ham Member QRZ Page

  7. N8VIL

    N8VIL Ham Member QRZ Page


    REASTON QRZ Member

    Why don't you save your self $200 worth of materials, time, effort, grief and buy an Ameritron choke for $20. If that doesn't fit, buy a choke from a junk SB200 off eBay.
  9. N8VIL

    N8VIL Ham Member QRZ Page

    On a whim I called Yaesu and the parts lady said that the plate choke is still available for $23.oo. I would have ordered it today but I left my wallet at home when I went to work. I am going to see if the doorknob caps in the final cage are still available also. Mine in the amp look good but if available and price is good might order those as well. Not worth my effort and material cost to rewind the choke myself at that price. That choke must have been used in later design amps to be still available as a service part. I will find out for sure tomorrow morning. I also found another NOS Cetron tube for $60.00. Figure I will have about $130.00 into the amp when I am done.
  10. N8VIL

    N8VIL Ham Member QRZ Page

    I want to keep it original as possible so everything fits nicely in the final cage. I figured about $20.oo to rewind myself. $5.00 magnet wire and $12.00 for the GC Electronics Q dope. I would reuse the original ceramic coil form.

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