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
>>
>>
>