I keep seeing messages about Kevin's cheat sheet but I never se the cheat 
sheet.  Did I miss its postin?
The other Howard, WA9RYF
----- Original Message ----- 
From: "Steve Dresser" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 16, 2010 3:09 PM
Subject: Re: Kevin's amplifier tuning cheat sheet


> Steve,
>
> I probably wouldn't look at plate voltage very often, but I'd sure like to
> know more about grid current, and maybe even plate current.
>
> Steve
>
> ----- Original Message ----- 
> From: "Steve" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, August 16, 2010 15:41
> Subject: Re: Kevin's amplifier tuning cheat sheet
>
>
>> Yeah, I have my tuning aid connected to the amp.  I don't look at the
>> plate
>> voltage very often.
>>
>> But, when I tune, I dip the plate tuning knob, and then turn the plate
>> load
>> until the plate current starts to rise a bit.
>>
>> I don't know, without seeing his cheat-sheet, how reliable that is except
>> as
>> a rough guide.  This is because your antenna rig characteristics will
>> influence that somewhat.
>>
>> I did slightly damage my 811's a couple years ago when I forgot to change
>> the band selector on the amp.  I now get about 590 watts out instead of
>> 690,
>> but that isn't a big deal.  But, when it comes time for a replacement,
>> I'll
>> grab the 572's.
>>
>> I would expect that one needs to neutralize those and the plate caps have
>> about 1800 volts on them.  Not sure I'd want to be probing around that
>> area
>> much even with an insulated driver.
>>
>> Steve, K8SP
>>
>> ----- Original Message ----- 
>> From: "Steve Dresser" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Sunday, August 15, 2010 9:48 PM
>> Subject: Re: Kevin's amplifier tuning cheat sheet
>>
>>
>>> 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
>>>>>
>>>>>
>>>>
>>