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. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Oh boy I agree totally about those video's some are just really wrong and even I can see that with no more experience I have concerning amps. I realize too what you're saying about the antenna tuner, I understood that well before posting. Low power adjusting is fine and it works like you've described, that said however I do always check twice, once on low, once on high. I have a good reason for doing so, "vision". I don't see as well as I did, so I check everything I do at least twice and that might seem a waste but for me it's just a part of life.

    Like you said normally no adjustments are needed on high if you got it right on your low power setting.

    My reasoning for letting the amp warm up for 30 minutes is that I have no idea when the amp was last used. It gave me a chance to monitor the amp. The reason I did that was because for several years I did restore work on Antique Receivers. You're dealing with stuff that has long outlived it's intended service life. Caps fail and often cause damages to other circuits. By monitoring the amp, even though it was in idle, I could check for voltage spikes, current increases and very possibly save my rig from certain damages. Which is a great concern for me, they just don't make FT-900's any more or anything like them. Hi Hi!

    I am sure you are fully aware that 572B's have a really bad reputation for flash over After they have been out of services for a while. I don't fully understand this but again out of of caution I let them toast in at idle before I put them under a load. Granted that might be a might over kill letting them warm up for 30 to 40 minutes. I don't mind a one bit to take every precaution I can to protect both the amp and rig, I can pay the electrical bill but I can't replace years of good service from that rig. One of the things we learned in Antique Receiver Restoring was to check the thing out totally before putting any voltage on it, after you checked it out, you put it on a Variac and brought it up to voltage slowly and you kept checking it. Even after repairs were made this was the process I was taught.

    Granted I didn't use a Variac on the amp I just wanted to make sure it was in sound. Next round I'll be more confident and let it warm up like the manual says.

    That Plate and Load thing has always seemed flaky to me, Honestly it has. I have never really got that, if you look at different amps and their manuals, it seems they all have some different description for basically the same goal. I just needed a brain refresher, I am glad you took the time to explain this, and give the example. I remembered years ago, paying attention to the watt meter and actually with a cross over meter, you can see the SWR drop and wattage go up when you got the amp loaded. Best I recall... but see this is the problem, It has been years, I mean years since I even owned a amp of any kind and the memory just isn't what it used to be. Things I did a lot I seem to recall a lot more than other things I didn't do a lot. Back then I just really did not see the need for an amp and to be honest I still don't so I really just didn't use one very often.

    As for tuning on the air, my first tune up, I should have mentioned I did use a dummy load, I did also tune some on the air. I really shouldn't have done that. You are absolutely right about that. I had just taken the dummy load out of line after messing about tuning and went to antenna. Really it was just a touch up tuning but it was on the Air. I was careful about it though, I checked to make sure nothing was on the frequency or above or or below it. I realize to just because I did not hear anything doesn't mean nothing was actually there. I will be more careful about that in the future. I thank you for pointing that out I appreciate it.

    Breaker trips. Again you are absolutely correct, breakers trip with to much load. By seeing the lights dim down in the room, I knew I was pulling a Balls load of current. The question came to mind about the plate voltage drop, I just wanted to make sure that was normal. I do know for sure I need to add a breaker and pull some wire from the panel and just put my Ham gear on it's own supply. I did not realize exactly what all was on that mains line and to be honest it has to much on it even without the amp. For 15 AMP breaker and going by code it is already over loaded without the addition of my gear on it. That has already been corrected, the guy that fixed it is coming back Saturday to install some outlets and a light in the shack if nothing happens. We just bought this house, it past a home owners inspection. From the electrician that did the repairs it shouldn't have passed due to that problem I ran into. Actually in the fall, he will be coming back and install an entire new panel and upgrade some other issues he found. I would have never known had we not had this conversation, never known I had a fire risk going on according to him. That was a pretty scary thing to discover.
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Can't hurt anything, just wastes time and power.

    When you tune the PLATE and LOAD controls, that can't possibly change the SWR. So, you wouldn't see SWR drop by doing this, ever. Watching for a plate current dip, IMO, is generally a waste of effort because looking for the "peak" in output power accomplishes the same thing and might be much easier to see. For example, while an "under" loaded amplifier might have a sharp, distinct and easily seen dip in plate current during tuning, a "fully" loaded amplifier might have a very shallow dip that you'd easily miss. But it would still show a distinct peak in output power. I'd focus on just looking for that.

    Yeah, if you adjust your antenna tuner at LOW POWER (the lowest power possible to get indications) and adjust it for a great match (close to 1:1), then switch to the dummy load to tune the amplifier itself for maximum output power, when you switch back to the actual antenna/tuner combination there is usually NO reason to "fine tune" or "re-peak" anything. Repeatedly doing this will wear out your amplifier faster -- and I know that's not what you want to do. You're not helping it with all the fine tuning.
     
  3. KE4CIJ

    KE4CIJ Ham Member QRZ Page

    Good Morning, Thanks for the input! A couple of hams visited last night, one of which does repair work in the State, about 40 years experience. Had him check out the amp and he said it was a fine example which really made me happy. That said, I showed them how I loaded it, which took me about 10 seconds, I'd guess on a fresh band and this time I did use my dummy load. Anyways I did it like you said, basically so he checked me out on that and said I was right on track. Like you, he said the same thing just pay attention to not let it run past the .5 and I should be just fine. Okay, I was pretty confused on the SWR conversation because I could see a change when increasing power on the meter. Not a great change but you could visual see a change, maybe a needles width or sometimes depending on band and tuning, you could see an even greater change. I was really confused by that, so anyways he explained that to me, I had used 3 different meters as examples but he did clear that up for me so I get that now. Depending on settings, basically what I am seeing is sensitivity changes, that is about the best I can do to explain his explanation without getting overly complicated here. Another words, I really wasn't seeing anything to be that concerned about.

    He did absolutely agree with my electrician that I needed to get the panel replaced and run outlets for the ham shack. After all the schooling we made some several contacts and got really good reporting, had a fun time. Learned a lot in the process, I was very happy they came by it was a lot of fun and good food!

    Between the both of you, I am good to go! For me posting and trying to convey my intent is hard and often times I confuse the crap out of the reader! Anyways, I wasn't to far off and you guys got me straightened out. I think my biggest problem was being afraid I would break my radio which I wouldn't do on purpose for no amount of money. That old radio is near and dear to my heart....That all said, I am good to GO! Thanks for the help!
     
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