The new Fl-2100B

Discussion in 'Amateur Radio Amplifiers' started by WB7OKU, Jul 22, 2020.

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  1. WB7OKU

    WB7OKU Ham Member QRZ Page

    I got the amp today. The tubes are still a few days off. The first thing I did was open her up and see just how bad it was. I was surprised that it didn't look like someone had taken a flame thrower to it. I have had mixed luck with "working" internet purchases in the past. I think the only thing that is a 'have to fix' is the door knob at the top of the plate choke. This looks like a dreaded cracked capacitor (Picture included). This is a replace, right?
  2. N8VIL

    N8VIL Ham Member QRZ Page

    Just by that picture, replace that cracked capacitor and the parasitic supressor resistors. Look at the plate choke for burned spots. The amplifier was probably used often by someone. I think they are nice little amplifiers when restored and used properly.
    W4NNF likes this.
  3. F8BDX

    F8BDX Ham Member QRZ Page

  4. G3YRO

    G3YRO Ham Member QRZ Page

    You'll find it very difficult to find a Doorknob capacitor to replace that Anode Coupling Capacitor (C222) that is the right length and with the right screw threads . . .

    SO here's a tip . . . use C221 (the Decoupling Capacitor after the RF Choke) in it's place, and fit any old doorknob capacitor in place of C221.

    ALSO . . . take the fans out and dismantle them . . . clean each part, then lightly oil the bearings when you re-assemble them . . . they will likely spin much faster ! (that is probably why that capacitor has failed - I had one of these Amps for 35 years and ran it very hard, with no failures!)

    I would also ignore any suggested mods you find online, like changing the Bias system . . . this is basically the same as in the Collins/KW/Heathkit linear amps of the same era, and works just fine (as long as you don't try using Russian 572Bs, which are very different)

    And the Electrolytics Yaesu used are very high quality . . . I have never known them need replacing.

    As it has a proper chassis, you will find these Amps much easier to work on than the likes of the AL-811 !

    The only thing that is annoying to me is that they didn't fit a case with a lift-up lid, like on the FL2000B, which is basically the same Amp. So you have to take the case off to change the PA Valves. (you could always fit the case from a scrap FT101, which does have a lift-up lid)

    Roger G3YRO
    Last edited: Jul 22, 2020
    W1TRY, W4NNF, K4AGO and 4 others like this.
  5. VA3QY

    VA3QY Ham Member QRZ Page

    I am running a parallel thread :). we can merge these two.

    PM me, i will send you the link where i got the capacitors from.
  6. WB7OKU

    WB7OKU Ham Member QRZ Page

    I got my tubes today. The transport gorillas tried, but failed to break them.

    I spent my day running a new 20 amp 120v line and not getting very far at all. Retrofitting wiring in a concrete block home is vastly different than the stud construction I grew up with. Another day of pulling wire and I can work on the amp.

    So having looked things over and read a whole bunch of opinion. I think Roger has a point. The only modifications I see that I need is a fuse in the high voltage line and a circuit to let my solid state transceiver key the amp. I would have put in a soft start, but 120 volt line in probably doesn't need it.

    I thought the parasitic suppressors looked pretty decent. Is it an age thing?

    I will get a door knob capacitor from Eastern Europe. It probably has metric screws, but I have a lathe. For some reason Eastern Europe can get capacitors here a month quicker than Russia. I will continue to look for a US made unit but doubt I will find one I am willing to pay for.

    The bottom of the amp is really clean. The top side is much dirtier. Can I spray it with a kitchen cleaner and wipe it?
  7. N8VIL

    N8VIL Ham Member QRZ Page

    Every older amplifier I have worked on with carbon composition resistors, after removing them out of circuit, tested way off value. That is the reason I mentioned it.
  8. VA3QY

    VA3QY Ham Member QRZ Page

    What is your recommendation for replacement?
  9. WB7OKU

    WB7OKU Ham Member QRZ Page

    The "Everyham's HF Amplifier" in the 2017 ARRL Handbook calls for 47ohm 3W metal film resistors. That amplifier is similar to ours and other similar commercial amps.
  10. WB7OKU

    WB7OKU Ham Member QRZ Page

    I took C222 out tonight. It looks like it is a 3Kv unit. What does RDA-30 mean?

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