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
>
>
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