Hey, Steve:
Do you want Kevin's cheat sheet?
I'll send it to you if you'd like it.
Tom Behler: KB8TYJ
----- Original Message -----
From: "Steve" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 16, 2010 3:41 PM
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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