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
>>>>
>>>>
>>>
>
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