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. KA0E

    KA0E Ham Member QRZ Page

    Larry, that should work, as you described

    Attached Files:

  2. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Looks like we both got that coffee! It's near 5 AM now so I will be hitting the coffee from now till day light. Thanks again for sticking with me here and giving me the nudges. Everyone has been really supportive. Yes, by looking at that diagram and going on and reading my manual that idea of wiring came from that.
    This is my 1st experience with the FL-2100 and I hope it will be a good one. That said, I still worry I'll goof and make a mistake.

    My friend has put it in my head of certain doom when I cut on the FL-2100 B and start to use it, so I have actually dreaded the day. He had a very bad experience early on with his FL-2100.

    That is a huge reason why I started this thread, old saying "measure twice or thrice and cut once" is my motto concerning this amp.

    In short, what happened to him, he had weak tubes, replaces tubes, needed to make an adjustment which requires him for some reasons unknown to me to be in the bottom of his amp. Not sure his reasoning on that, but that was what he was doing, had the amp on it's side, That was the first mistake, I think, 2nd mistake is he cut the amp on, 3rd mistake he put it in the operate mode, keyed his rig, he was never the same. Both tubes melted down in seconds, caused a huge explosion, smoke filled the shack and a dead FL-2100 remained smoking. When the life returned to my buddy, he quickly shut the power off, removed the debris from his pants and carefully unhooked the smoldering remains of said 2100. Hooked his rig up and when it came back to life, he checked it out for damages, when he keyed the mike up to start a QSO with a ham, making sure he was still living he needed quick human contact, he begin to hear himself speaking through his rigs speaker as he called out for a human being, any human would do at that moment.

    It must have been a site to see as several days past I went for a visit. His shack had an a certain smell to it, that it never had before, an electronic burned smell along with a really horrible stinky smell. Not sure what that was at all but it might have been something to do with the pants he ruined during the Event as he put it.

    He showed me his rig and said listen to it, it had talk back he did not want. If you could have saw the poor mans face when he said, my rig it sounds like a CB radio with that crazy talk back! His eye's was almost in tears and the fear came out when I said, well hey it isn't that bad, let's check the amp out! Utter fear came over him, is all I can say!

    He, the amp and rig was never the same after that tragic day of him killing the FL-2100 and his rig. He had a slight pale look on his face, and now when he speaks of the event his face pales up and he starts to twitch a little.

    You'd just had to been there...

    In many ways after all was said and done, it was kind of funny. No harm came to him but his pants was ruined from debris stains. I am very glad he wasn't hurt or fried, it just goes to show you when you don't know what you're doing, leave the amp alone, either seek a lot of advice or seek the technician for repair.

    My dread is, I will make some sort of goof concerning my amp, and because he's warned me over and over for years to stay far away from the FL-2100. If something goes wrong, he's going to dance and prance around saying I told you so, I told you so! Not that he wants anything bad to happen mind you, I guess though he would enjoy it as for years, I will bring up that day. Just to see the fear come on his face.

    Hence the purpose of measuring thrice and cutting once!
    Last edited: Jun 10, 2014
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Nobody who is unqualified to work on live amplifiers ever should try to do that.

    Your friend is lucky to be alive.

    What happened wasn't the amplifier's fault, it was his. There aren't any adjustments on the bottom side of the amplifier. After safely replacing tubes, you put the amplifier cover back on and with the amp sitting on the table or bench as it's supposed to be (feet down), power the amp on.

    The tubes must be operated with the base pins oriented in the correct direction, under power. You can't apply power with the amplifier "on its side."
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Re-read post #6, it didn't contain any errors. The "center pin" of TX GND goes to the RY screw terminal on the amp. The outer conductor (shield) of the TX GND goes to the "E" screw terminal on the amp (either one, they're connected in parallel and are only chassis ground).

    Impossible to get this wrong unless you really try.:p

    Yes, that's the way ALC connects but I doubt you'd need to use it with the FT-900 and that particular amplifier. I'd start out not using this connection.

    The caveat here is the ALC is not a "rig output," it's a "rig input," and the "signal" comes from the amplifier. It's possible to damage the rig if a failure in the amplifier occurs. If you can adjust and tune up so the amplifier cannot be overdriven, I wouldn't bother with this connection. It was mostly provided for the earlier generation Yaesu tube and hybrid rigs that could run >100W output power. Some of them could run ~200W output power.
  5. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Well today is the big day, I am going to hook that puppy up, maybe not on the air but on a can for sure. I wanted to thank you for all your help and I appreciate it greatly. Thanks for reading the story of my friend as well! The entire thing really put me in doubt but I am sure I can do it with little efforts on my part, just mind you you'll not be hearing of Ke4CIJ laying any amp on it's sides, covers off and firing it up for any reasons period! In fact you'll not be hearing of me even taking the covers off that amp for if the thing breaks to the shops it goes! Again thanks and if you have any advice concerning tuning or anything you think my be good advice let me know!
  6. KA0E

    KA0E Ham Member QRZ Page

    Larry, since you are in a learning curve with this amp, I don't want you pick up something here that is incorrect and
    take it as law...

    There ARE adjustments on the bottom of the amplifier for the tuned input on each band. When installing new tubes
    they sometimes need touching up, sometimes not.(hard to find a good 572 right now, and some are not compatible
    in this amp without mods)

    The key to the 572b amps is they don't need high-voltage flowing through the tubes to tune the input. That was your
    friends mistake. They come out close enough without the HV. It even tells how to do this in the manual.

    Good luck on the FL2100B. I was a little nervious firing the one I just sold also. I bought it from a friend of mine 15yrs
    ago. He bought it new in 1978 and never used it..It sat here for 13 yrs until I finaly fired it up 2 yrs ago. Talk abt NOS..

    Anyway sold the amp a while back so someone could appreciate it for a while...

    73, Keith
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, that's true and the manual does tell you to disconnect the lines from the HV transformer windings to do that, which isn't such an easy thing to do.

    In my experience, having used many FL-2100s over the years, this has never, ever been necessary. The tuned input networks are low-Q pi-networks that don't need retuning with any kind of 572Bs I've ever used (Cetron, Svetlana, or RF Parts "Chinese" tubes). The match is fine with any of them.

    The FL-2100 IMO is an SB-200 knockoff. They saw the SB-200 and said, "We can make this!" but they used cheaper parts and it was never quite as good an amp as an SB-200. The 2100 has several weak links, and one of them (which usually fail) is those silly HV blocking/bypass caps they used. "Most" 2100s that have crossed my workbench over the years (probably 20 of them or so, over a couple of decades) has had failed caps. They just weren't very good. I'm guessing they picked them up from someone making HV caps for TV sets, which operate at 15.75 kHz in that application and operate with much lower currents.

    Heath used better parts.:eek:
  8. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Good Morning guys, last night we had horrific storms, I had a close lightening strike near the house which nearly scared me and the pup to death. It sounded like a bomb went off, about the same time I keyed up my rig to check into the Mar time net. You talk about doing some moving for an old man, I did some fast unhooking of cables, that storm just appeared out of now where, no forward warning whatsoever! Not a sound no thunder, nothing, just BOOM and the sky opened up!

    Afterwards and I was able to get myself back together, I found some really nice GOLD Shielded heavy RCA cables, I had for something. I made a nice cable out of that and made a connection on the back of the amp using female RCA type connector block I removed from a broken Play Station. Came out pretty good.

    So it's all hooked up now, but I have a couple of questions maybe not so important but I thought I would pose them here...

    If I read the manual correctly, it suggests you can check the SWR of your antenna using the FL-2100B meter while the amp is in Standby. Okay being I haven't even turned the amp on just yet and only have now got it connected up, I was just curious, DID I read that correctly? Can I use it's built in meter to check the SWR?

    Also here's the way I've got every in line coax wise and I wanted to make sure it was okay and would give me the best RF path out.

    FT-900, into Watt Meter/SWR meter, into FL-2100 into Dentron Super Tuner into Watt/SWR meter, into Hy-gain Ground Mounted Vertical.

    I really do not need the tuner in line because the antenna has a low SWR on most bands but for 20 meters, something I need to re-address as I am not so sure why the SWR is a little higher on 20 meters than other bands. I've had to re-wind the coil on 15 meter band because that coil was broken years ago. But that had nothing to do with the 20 meter section because it was high before the work. I had thought by fixing 15 meters it would also correct the 20 meter issues but it didn't so I am now thinking to re-wind that coil even though I can't find anything wrong with it. The SWR is about 1.9 on 20 meters but all other bands is less than 1.5 readings.

    The coax jumpers are all 3 foot jumpers through these connections, and exactly 100 feet of coax to the antenna. I am using a low loss, mini type coax that is rated for best I recall 3k watts.

    Maybe not the most important questions but I feel it is best to ask before I make my tests. I just want the best outcome here, I keep thinking about my buddy! LOL

    Oh and I wanted to ask any suggestions on tuning the amp? Any help on that would be greatly appreciated as it's been near 25 years since I even owned anything with a tube in it. Last radio I owned was a 101 back in the 90's I think not sure but that was the last tube I owned and the last tube amp I owned was back then too!

    Best regards,
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, you can. It's always "in line" as long as your rig and antenna are connected to the amplifier, and it doesn't matter if the amp is on or off, or even plugged into a source of power. It's passive, and always works.

    You've got some redundancy there, and the second watt/SWR meter installed in the wrong place. No reason to use two meters, at all; and the series connection should be:

    FT900-->amplifier-->watt/SWR meter (after amplifier, connected to it's ANTENNA outlet)-->Dentron tuner-->antenna.

    If you connect a watt/SWR meter between the tuner and the antenna, no matter how you adjust the tuner you won't ever see the SWR change, because that's not the right place for the meter. It must be between the amp and the tuner.

    I'd not bother with the "first" meter (between the rig and the amp), it's superfluous.

    That must be some really special "mini" coax. The only coaxial cable I know of that is "small" in diameter (.200" O.D. or so) and rated for 3K watts is Teflon cable like RG-142 or RG-400. If what you have is the standard "mini" cable, that's probably RG8X or RG8M or "mini 8" coax, and that sure isn't rated for anything like that kind of power. Normally RG8X will handle legal-limit power on HF (1500W) for SSB or CW service as long as it is terminated in a good match (low SWR at the antenna itself). It will not handle a kW on AM or RTTY (continuous duty cycle) or under high SWR conditions. Continuous duty can melt it, and high SWR can make it "flash over" and short out.

    But the FL2100 output is normally in the 650W range, and if your SWR at the antenna is 2:1 or so, everything should be fine.
  10. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Ok I did some checking on the coax, you're correct it's rated 1.5kw and I know why I made the mistake, the coax for the tri-band antenna is marked 3kw right on the hard shell cover and it's a large heavy wire large as my thumb about it, it was in a box in the basement. Being old I just made the mistake, I was using the same wire...which turned out to be a huge DUH on my end, the mini isn't even the same color! But still I am glad I asked..because I gained some on that by double checking...

    Okay I changed the setup to what you have recommended here, so I have it all in line like you mentioned, one reason I had the meter after the radio was to make sure I wasn't getting a higher SWR back to the set. The 900 meter is hard for me because of the color...orange or whatever color that is, really gets me.

    Okay next,

    Any suggestions on TUNE UP for the AMP?

    one thing I am not getting because the manual really doesn't tell you I don't believe, is am I looking which meter to get the dip?

    I assume I should be looking for dips in the Plate Current, which would be on the SWR Meter?

    One is a Plate Voltage meter as it plainly says that on the meter. The SWR meter is a combo meter right? So if I am right it will read AMPS in one position of the SW which should be IP and SWR in the other position, is that right?

    So what I am looking for, is a dip in reading and it suggest keeping it under .2 amps is what I'm getting out of the manual?

    Not to exceed something like .5 amps is that right?

    Just double checking here! I really appreciate your time to by the way, I have learned a lot from you guys! Seriously, it has got me to exploring again and researching a lot so it has been a real blessing for me. Due to health problems for the past several years I sort of put my radioing on hold and put my radios in a box. The more I ask and the more I learn the more excited I get...I still have the health problems and still not really able to do a lot but what I can do is Enjoy!

    Thanks and 73
    Last edited: Jun 12, 2014
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