Sorry Steve - I sure don't have any to lend you!! It is a pisser when you've been so careful to know how it is so you can get it back and then it doesn't!! PatAt 08:15 PM 8/16/2010, you wrote: >Pat, > >I really hate it when I take something apart after carefully studying it, >and start to reassemble it only to realize that I'm not completely sure how >it looked before I took it apart. I would say it makes me tear out my hair, >but I have so little left. > >Steve > >----- Original Message ----- >From: "Pat Byrne" <[log in to unmask]> >To: <[log in to unmask]> >Sent: Monday, August 16, 2010 18:35 >Subject: Re: Kevin's amplifier tuning cheat sheet > > > > Agreed Steve - just my thoughts that changing tubes is something we > > can competently do. Another thought I had - pay really close > > attention to how a something looks before you start working on > > it!! If I understand something closed and carefully open it I stand > > a good chance of re-closing it!!! maaybe that is obvious but I have > > carelessly taken things apart and then had a hell of a battle getting > > them back together!! Not long ago the flushing mechanism on one of > > our toilets fell apart. I spent a really long time trying to figure > > it out and I lost!! Called our oldest son and he came by and had the > > job done in two minutes!!! And now that it is the way it is supposed > > to be and I understand it, I'll be able to fix it myself the next > > time!! (Probably)!! > > Thanks. > > Pat, K9JAUAt 08:28 AM 8/16/2010, you wrote: > >>Pat, > >> > >>I've changed many a tube, but I don't see any reason to do so while the > >>811s > >>are still working. > >> > >>Steve > >> > >>----- Original Message ----- > >>From: "Pat Byrne" <[log in to unmask]> > >>To: <[log in to unmask]> > >>Sent: Sunday, August 15, 2010 22:16 > >>Subject: Re: Kevin's amplifier tuning cheat sheet > >> > >> > >> > In the old days!! when we had tubes to change it was never a > >> > problem. Occasionally tubes had to be neutralized - that was > >> > something that as a blind man I couldn't do. It involved watching > >> > grid current and making adjustments to stop that current from > >> > showing. Only a problem with triodes and no longer an applicable > >> > concern. > >> > Not to demean anyone's knowledge or abilities but the tubes will only > >> > go in the "right" way and the plate cap just presses on to the top of > >> > the > >> > tube. > >> > Hope this helps. > >> > Pat, K9JAu At 08:48 PM 8/15/2010, you wrote: > >> >>Tom, > >> >> > >> >>You don't need an additional meter--the ones you need to read are > >> >>already > >> >>on > >> >>the amplifier. I don't think I'm quite ready to change the tubes, > >> >>especially for a $200 price, although I'll probably do so if I have to > >> >>replace them. > >> >> > >> >>Steve > >> >> > >> >>----- Original Message ----- > >> >>From: "tom behler" <[log in to unmask]> > >> >>To: <[log in to unmask]> > >> >>Sent: Sunday, August 15, 2010 21:21 > >> >>Subject: Re: Kevin's amplifier tuning cheat sheet > >> >> > >> >> > >> >> > Steve: > >> >> > > >> >> > > >> >> > Well, so far, your experiences come pretty close to mine. > >> >> > > >> >> > Like you, I want to get someone sighted over here sometime with a > >> >> > meter, > >> >> > and > >> >> > a familiarity with the amp and its characteristics, so I can > >> >> > determine > >> >> > how > >> >> > I'm actually doing. > >> >> > > >> >> > All of this adds up to why I bought the 572B's. > >> >> > > >> >> > I figured that with more robust tubes, I at least have less of a > >> >> > chance > >> >> > for > >> >> > all heck to break loose if I happen to make a blunder in the tuning > >> >> > process. > >> >> > > >> >> > 73 from Tom Behler: KB8TYJ > >> >> > > >> >> > ----- Original Message ----- > >> >> > From: "Steve Dresser" <[log in to unmask]> > >> >> > To: "tom behler" <[log in to unmask]> > >> >> > Sent: Sunday, August 15, 2010 8:34 PM > >> >> > Subject: Re: Kevin's amplifier tuning cheat sheet > >> >> > > >> >> > > >> >> > Tom, > >> >> > > >> >> > Since this is my first tube amplifier, I attribute my success more > >> >> > to > >> >> > luck > >> >> > than experience. Nevertheless, a few things seem clear to me: > >> >> > > >> >> > First, as long as you try to run the amplifier within specified > >> >> > limits, > >> >> > you > >> >> > probably won't get into trouble. For that reason, I avoid driving > >> >> > it > >> >> > with > >> >> > more than 70 watts of continuous carrier. > >> >> > > >> >> > Second, things break down in a hurry if the plate current is high. > >> >> > Therefore, I adjust the plate current so the amplifier is putting > >> >> > out > >> >> > maximum power, which means the output circuit is in resonance, which > >> >> > means > >> >> > the plate current is at minimum. > >> >> > > >> >> > Finally, I worry about the grid current which, from what I > >> >> > understand, > >> >> > should be high enough to keep the finals biased properly, which > >> >> > means > >> >> > that > >> >> > I > >> >> > adjust it to the point where the output power begins to decrease. > >> >> > > >> >> > Thus far, I haven't blown anything up, and nobody has ever reported > >> >> > that > >> >> > my > >> >> > signal is non-linear, which I hope means that I'm operating things > >> >> > pretty > >> >> > close to where they should be. One of these days, I'll be lucky > >> >> > enough > >> >> > to > >> >> > have someone sighted around to read the meters and see how close I > >> >> > really > >> >> > am. Meanwhile, I'll just be alert for smoke, and hope I don't smell > >> >> > any. > >> >> > > >> >> > Steve > >> >> > > >> >> > ----- Original Message ----- > >> >> > From: "tom behler" <[log in to unmask]> > >> >> > To: "Steve Dresser" <[log in to unmask]> > >> >> > Sent: Sunday, August 15, 2010 19:59 > >> >> > Subject: Re: Kevin's amplifier tuning cheat sheet > >> >> > > >> >> > > >> >> >> Well, Steve, you are much more experienced than I am with these > >> >> >> things, > >> >> >> and my thought at this point would be: "If your strategy works, > >> >> >> don't > >> >> >> change it.". > >> >> >> > >> >> >> I have to admit that I still get a bit apprehensive when doing the > >> >> >> tuning > >> >> >> procedure, but I just take my time, and work through each step, > >> >> >> giving > >> >> >> things periodic breaks in the process and, so far, so good. > >> >> >> > >> >> >> Tom Behler: KB8TYJ > >> >> >> ----- Original Message ----- > >> >> >> From: "Steve Dresser" <[log in to unmask]> > >> >> >> To: "tom behler" <[log in to unmask]> > >> >> >> Sent: Sunday, August 15, 2010 5:51 PM > >> >> >> Subject: Re: Kevin's amplifier tuning cheat sheet > >> >> >> > >> >> >> > >> >> >> Thanks, Tom. I have considered connecting a VCO across the > >> >> >> amplifier's > >> >> >> meters so I could actually read the plate and grid current, but my > >> >> >> "maximum > >> >> >> smoke" method seems to work, and laziness prevails. Nevertheless, > >> >> >> it's > >> >> >> good > >> >> >> to know the actual current info. > >> >> >> > >> >> >> Steve > >> >> >> > >> >> >> > >> >> > > >> > > >