Yaesu FL-2100B Plate Choke Rewind

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

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  1. KM1H

    KM1H Ham Member QRZ Page

    Even the type/thickness of the wire insulation can shift a resonance to where you dont want it. Also remember the wire is metric and not AWG.

    OTOH it and the TL-922 version are the forerunner for the one Ameritron copied (even then there were 3 production versions before they got it right) The current Ameritron should fit and at least you know it will function in the FL-2100.

  2. N8VIL

    N8VIL Ham Member QRZ Page

    I really over complicated this repair. The plate choke and doorknobs were still available from Yaesu parts dept. Plate choke $21.90 and doorknobs in final cage about $10 each (all 4). I have them ordered and they will be here in about 5 days. I would have never thought the plate choke would still be available as new on a 40 year old amplifier. Does not make sense to rewind my self at that price.

  3. W1QJ

    W1QJ Ham Member QRZ Page

    No, you are doing the right thing.
  4. N8VIL

    N8VIL Ham Member QRZ Page

    This is how I modified the bias circuit in my FL-2100B. The Svetlana bias circuit modification puts too much voltage across the relay (about 26 volts) and the bias voltage is too high for idle proper idle current for Cetron 572B tubes. I liked the idea of having a higher negative cutoff bias voltage to the tubes. Added this in case this may help someone out. The resistor is there for illustrative purposes (not right value) 1st picture is schematic (my design) 2nd picture is the voltage doubler circuit 3rd picture is the
    place where I will mount the 130 ohm 5 watt resistor. My next item is to add a keying circuit that uses a low current +5 volt to be friendly on newer radios. The resistance of the key circuit affects the idle current bias. Closure must be as close to ground as possible. This is also the case on the original circuit. I might use a dc-dc converter circuit, to get a positive voltage to operate a small relay to close key line. I thought about a transistor switching circuit but the .7 volt drop affects the idle bias voltage.

    DSCN1488.JPG DSCN1484.JPG DSCN1479.JPG
  5. N8VIL

    N8VIL Ham Member QRZ Page

    I forgot to mention that you have to isolate the grounds for the power and operate indicator lamps for the doubler circuit. The lamps run off the raw 13 volt AC supply. Also not on the schematic is a diode to dampen the relay back pulse when the relay is de-energized.
  6. KD8DEY

    KD8DEY Ham Member QRZ Page

    You can make your own Q=dope from Styrofoam cups or Peanuts and a bit of touline much cheaper than you can buy it pre-made
    WA7PRC likes this.
  7. N8VIL

    N8VIL Ham Member QRZ Page

    I did a little reading on that last night. The article said that peanuts were better because in the Styrofoam cups they add titantium dioxide to brighten the white color of the cup. I have some touline in a can in the basement and some peanuts. I might give it a try for future projects.
  8. KD8DEY

    KD8DEY Ham Member QRZ Page

    the Titanium Dioxide settles to the bottom after a while and the clear "liquid" can be separated....doesn't hurt anything as far as I know.
    WA7PRC likes this.
  9. N8VIL

    N8VIL Ham Member QRZ Page

    I modified the Harbach SK-201 keying circuit by using a 22k resistor for R1 for -36v (original 100k ohm resistor for -120V)
  10. W9GB

    W9GB Ham Member QRZ Page

    Toluene is getting harder for consumers to acquire, in small quantities.

    Toluene is an intoxicative inhalant, so its possession and use are now regulated in many jurisdictions (24 states). The ACE hardware stores in Chicago suburbs no longer carry, since their local supplier no longer sells in less than 55 gallon drums (industrial size).

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