Yaesu FT-900 to Yaesu FL-2100B amp wiring questions?

Discussion in 'Amateur Radio Amplifiers' started by KE4CIJ, Jun 8, 2014.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Before "tuning up" anything, see if the amp "works" and is being keyed properly by your rig by doing this:

    Connect FL-2100 output to your antenna or a kW-rated dummy load.
    Set FL-2100 meter switch to IP (viewed on the left hand meter).
    Set FL-2100 STBY/OPER to OPER (operate).
    Set FT-900 to SSB on any band. Do NOT modulate the rig (talk into the mike).
    Turn on the amp.
    Key the PTT on the FT-900 and watch the IP meter. It should raise to about 0.1A. This isn't critical, but it should raise to "something" and not be zero. The OPER lamp should be illuminated.

    Release the PTT on the FT-900. The amp should switch itself back to "bypass" automatically. You'll hear a relay in the amp switch (click) each time you press or release the PTT.

    If all that works okay, then you're ready to actually transmit and apply a signal and drive to it.

    Let me know if that all works okay.
  2. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    just got back so I will do all that in a bit and let you know the outcome...
  3. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Everything works fine. I did not load it or anything just yet but everything checked out, powered on fine, Operation light engaged on on and when I keyed the 900, the 2100 perked right up and relay keyed.

    Voltages checked out on the meter...

    Okay one question though, I even looked through the manual and I did not see anyways to calibrate the SWR meter?

    Did I miss that or is it in there? It just mentions the SWR meter Briefly or I missed something there.

    It may not even require to be calibrated but I have no idea. All it really said was "if it maxed out to use the Sen roller to adjust it back."

    Okay next, am I ready to attempt the loading procedure?
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page


    The SWR meter calibrates by transmitting wiith a carrier (not SSB) and in the FWD position, adjust the meter sensitivity control for a full-scale indication of the meter (without going beyond the last scale indication), then switch to REV and read the SWR on the SWR scale. That's the same as every other SWR meter in the world.:eek:

    But since you have an outboard wattmeter between the amp and the antenna tuner, I'd just use that one and forget about the meter in the FL-2100.

    To "tune up," with the amp powered on but in STBY, set the FT-900 on the band you want to use and the approximate frequency you want to use, switch the mode to FM and key the Yaesu; then adjust the power level control on the Yaesu for about 50W output power (not "full" power, which should be about 100W). Either bypass the Dentron tuner or if you can't bypass it, adjust it as you normally would for minimum SWR, just as you have evidently done when running barefoot.

    It would be even better to use a kW-rated dummy load instead of an antenna, that way you don't need the tuner at all and you won't create interference on the band.

    When the SWR is dipped (hopefully below 1.5:1 or so), or you're adjusted for 50W into the dummy load, you're ready to tune the amp.

    Set the amp's band switch to the band you're using and set the plate tune and load controls to the settings shown in the manual for that band. Those are approximate settings, but they're a good starting point. Always unkey (release the PTT) the FT-900 any time you flip any switch on the amplifier: Never flip the standby/operate switch or turn the bandswitch while actually transmitting -- this can damage the amplifier.

    Switch the amp to OPERate, and while watching the wattmeter (the one you have after the amplifier, in the antenna line) key the FT-900 PTT and adjust the plate tuning control for a maximum indication. Then, adjust the load control for maximum indication; then go back and re-adjust the tune, and then the load again, until both controls are adjusted for maximum output power.

    With 50W drive, output power should be around 500W or so. Look at the Ip (plate current) meter (make sure the FL-2100 meter switch is in the Ip position, not SWR) and see what it indicates. Should be below 500mA.

    If it is below 500mA, adjust the power level control on the FT-900 a bit more clockwise (higher) to increase the transceiver's output until the FL-2100 Ip meter indicates about 500mA. Then, while watching the wattmeter, make small adjustments to the FL-2100 plate tune and load controls for maximum output power again. When you increase power, usually you have to adjust the LOAD control slightly more clockwise to increase loading and achieve maximum output power.

    When output power is 600-700W and the Ip is about 500mA, you're done.

    This sounds complex, but really is very simple and the whole operation from start to finish, once you are familiar with it, takes maybe 5-10 seconds. Once you become very familiar with it, more like 5 seconds.

    Don't forget:

    Any time you change bands on the FT-900, you must also change the bandswitch setting on the FL-2100.
    When you "start" tuning up, always turn the power of the FT-900 down to about 50W to begin with; once the amp is "mostly" tuned, you can increase the power output until Ip is about 500mA.
    You must use a full-carrier mode to "tune up," can't use SSB for this. Best is actually CW, with a key plugged in and the key "closed." FM works just as well, but remember not to modulate the rig (or turn the mike gain all the way down) if you use FM for tuning, as you do not want a modulated signal on the air (unless you're using a dummy load only).
    And, never "key down" while tuning up for more than about 10-15 seconds at a time when the amp is out of resonance (that is, before it's really tuned properly). Once the amp is tuned up, you can transmit for much longer periods.

    When you're done tuning, flip the FT-900 back to SSB and use your normal mike gain settings -- you should be good to go.

    It's best to adjust "loading" while watching the amplifier grid current, which is the most sensitive indicator of proper tuning; unfortunately, the FL-2100 does not meter grid current (it should have), so you can't do that. It's one of the design weaknesses of that amplifier, but they work anyway.

    Have fun!
  5. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    I actually did that with the SWR meter, but I just wasn't sure about that and being it's not mentioned in the book, I was like duh! Well I think I got it, so now I will go try it out this afternoon if IF IF we can avoid the storms that have hit us every day this week. I am very glad you guys took the time, to give me some directions here. I had asked a couple of people about tuning and I get so many things on that it's just amazing really. Just for kicks try asking about amps sometime it will boggle your mind of how many conflicting things are said. I don't think anyone has a bad intent but they just make things a lot harder than they are really!

    This direction should be framed and used by anyone who wants to use an FL2100B be them new to amps or someone who has owned them before. These are BY FAR the best and easiest to understand, that I have read or seen.

    Ever see Youtube videos? I watched a dozen or so videos on this amp and walked away scratching my head. You see one and no two are the same if it concerns tuning!

    You'd think being they're the same type of amp being used, the tune up would be the same process no matter who does it. You'd think anyways!

    I feel just really blessed you guys came along to bump me in the right directions, great to have Elmer's no matter how much you think you know or how old you are or how long you've been into ham radio.

    So here you go! THANKS ELMER'S

    It's just a might comforting to know you're learning from experienced people!

  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If you have a proper dummy load, you don't need to wait for storms to pass -- the load is indoors and no antenna connection required.

    It really pays to have a kW dummy load if you own an amp. Tuning up "off the air" into a dummy load is easy, kinder to both the amplifier and other occupants of the band.:)
  7. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    I have a Oil cooled dummy load, had it for near 35 years, it's a huge dummy load, one on a paint can. The thing is the wall outlet and We get some really serious lightening and I don't use anything during electrical storms. Everything in the shack is unplugged and I either wait it out or just wait till another day.

    I lost one power supply due to lightening, had a radio burned up, it was never the same even though it was repaired. After that happened I grew feathers...

    But, I haven't lost any more equipment, that was at my old OTH though..so this go around at the new one, I am not taking any chances! LOL
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Wow, that's amazing.

    Probably not a well protected residential grid. Here we have huge lightning arrestors on all the power lines (owned by the utility) and they just sit there doing nothing, since we don't have any lightning!

    Well, let us know when you tune it up and test it out.
  9. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    You have to know where I live, it's well, it's like the arm pit of the universe, In most places they have fiber internet service, note I said most places! Here we have DSL! Unemployment for our working people is like 15 to 16% even though the claims are less. Don't take me wrong it's a beautiful area, near the parkway, lots of mountains and rivers, trout and deer. But it's also got it's bad side, high crime rate now, it compares to some major cities I have been told. Drug use is off the charts..It's just got really bad here since all the factories left. The county does the best it can but it lacks in a lot of ways...

    I'll keep you posted on the amp, I tuned it this evening on the Dummy load by the ways, It ran on the dummy around 600 to 700 watts depending on modulations. I found a very good video on the tune up later on this morning. He pretty much did it just like you described in your post and it was Easier than I remembered doing.

    If all goes well I am supposed to be treated to a weekend of PEACE so my plan is to escape to the shack down stairs and get it on the air for the 1st time on 40 meters being that band seems to be the best with my antenna, a ground mounted vertical for right now. It's all I was able to get up here since we moved and due to health reasons I just have to take one day at a time to see how up to doing something I am.

    Thanks again for all your help and advice!

    God bless!
  10. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Hey I was reading some of your posts on another forum, back from several years ago, you're really very knowledgeable concerning these amps we've been talking about. I was reading some of your suggested mods to another ham. I wish now I had researched this amp more so than I did, before picking it up, my original thought was to grab a Dentron amp they had. I had read a lot concerning Dentron and for the money It might have been a better idea to grab it instead of this one. The thing that sold me on this amp, was it's condition. It was a one owner and so clean, no scratches no dents, no dings. The insides were very clean, it didn't appear to be messed with at all. I couldn't see any changes inside the amp whatsoever, it all looked original, I do think the parasitic suppressors have been changed though. Everything else appears to be intact....

    One thing I was interested in, something I might could do on a good day is do a Cap Replacement, I found several kits offered up for not a lot of money. The kits supposedly come with all the caps for the amp. Power Supply and others plus a few resistors and I also found new parasitic resistors.

    Do you think that would be worth while to do in the winter months during down time? Or would you just move the amp along and let someone else take care of those things?

    As for other mods, I don't know if I am up for that due to health issues but I think I could do the Cap Mods over a few weeks. I was reading something about a Relay mod, I don't know if my hands would let me do that or not.

    I really like the amp, I like the size and weight, it's not so large it takes up the entire desk. I also like the reports I got off it yesterday. That being said though, the more I read about them, the more put off I get and regret I got it. But being I have it and will be stuck with it for a while, I want to take care of it and do what is right by it and I think installing new caps in a 40 year old amp will certainly wouldn't be a bad investment.

    What's your thoughts on this, should I invest in the new cap kit or just let the amp go to a new owner? Honestly, I think over several weeks I could install new caps through out the unit but it would take me a lot of time, the time part is of no concerns. I know I could do a good job as far as that is concerned but still someone else might be as turned off by the notion of the cap upgrade.

    Yea, by reading tons of negative comments on these things it does sure make me wonder about it. Sort of concerning really but who would have thunk Yaesu from back in the day would have made such serious blunders. They really should have just copied the SB200 totally and not added their own twists, they would have been better for it in the long run.

    Anyways, what's your thought on the Cap upgrade? Worth it or not?
    Last edited: Jun 15, 2014
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