On Jun 26, 2006, at 8:40 AM, Joe Isabella wrote:
> Since when does management listen to engineers?? They listen to
> the mighty $$$$. Just like the Space Shuttle Challenger disaster
> chain of events, the engineers said "NO!!", but management said
> "We'll lose millions!!", so they launched with frozen O-rings. We
> lost more than millions...
Amen, Joe. They were also under pressure from the Administration to
launch for political timing reasons.
>
> If you want a "perfect" amp, build it yourself.
Indeed, Joe. The last amplifier that I built was an 8169 in AB1. I
tried to do everything perfect based on what I learned from blunders
I made during the Plywood Box project, but two mistakes turned up:
1. I did not install one wire that was on the diagram, so nutti'
happened when I turned it on. and 2. I got a HV-RFC resonance too
close to 14MHz, which caused a choke fire.
> Better yet, let's all do that, swap hardware, and see how perfect
> they are!! Bet you a cup of coffee none of 'em are...
>
> :-)
>
> Joe, N3JI
>
>
> ----- Original Message ----
> From: Gary Smith <wa6fgi@sbcglobal.net>
> To: craxd1@verizon.net; amps@contesting.com
> Sent: Monday, June 26, 2006 10:26:10 AM
> Subject: Re: [Amps] IM distortion and such
>
>
> Coming from Mr Matney, a most excellent point of view.
> Particularly where
> one could be sued into bankruptcy and then oblivion.
> Gary...wa6fgi
>
>
> ----- Original Message -----
> From: "Will Matney" <craxd1@verizon.net>
> To: <amps@contesting.com>
> Sent: Sunday, June 25, 2006 5:39 PM
> Subject: Re: [Amps] IM distortion and such
>
>
>> It's according to what kind of audio amp. Guitar amps are designed to
>> purposely introduce distortion. That's where the squeal of the
>> electric
>> guitar comes from. The bands actually prefer this. However, if one
>> is an
>> engineer, and you have a maximum rating curve, it is a liability
>> to ever
>> go outside the curve into the over load region. That's like saying
>> I'll
>> put my stamp on this bridge which I know is going to deflect more
>> than
>> allowable published tolerances, and that I think it can get by
>> with the
>> added stress, even though I am over the maximum curves for tensile
>> and
>> yield strength. Then an automobile drives over it and falls in the
>> river.
>> Who's liable? Whether electrical or mechanical engineering, an
>> engineer
>> should always look at this. Though running a tube out of spec
>> probably
>> wont kill anyone, the manufacturer better be ready to replace
>> tubes or the
>> entire amp if the customer is dissatisfied as a suit will sure
>> follow if
>> they don't. If ran in spec, one has nothing to worr
>> y about, and has published data to fall back on. This from an
>> engineers
>> point of view.
>>
>> Best,
>>
>> Will
>>
>>
>> *********** REPLY SEPARATOR ***********
>>
>> On 6/25/06 at 4:00 PM k7fm wrote:
>>
>>> Tom said:
>>>
>>> "I think you are really saying an engineer shouldn't ever
>>> design outside what is actually published on a spec sheet
>>> that only covers a limited number of situations under any
>>> condition, even if the component manufacturer, field
>>> history, or direct testing show otherwise."
>>>
>>> It might be easier to grasp what Tom is saying if you think of audio
>>> amplifiers. Assume a tube manufacturer specifies a tube for audio
>>> distortion. However, the manufacturer of the audio amplifier is
>>> looking
>>> for
>>> minimum distortion. If he finds that running the tube outside of
>>> the
>>> curves
>>> specified by the tube manufacturer gives consistently lower
>>> distortion,
>>> then
>>> it would be good engineering to do so. In some cases, tubes
>>> might be
>>> hand
>>> selected for those parameters that met the goals of the
>>> engineer. In some
>>> cases, the plate dissipation might be exceeded to get closer to
>>> class A.
>>>
>>> Colin K7FM
>>
>>
>>
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>>
>
>
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R L MEASURES, AG6K. 805-386-3734
r@somis.org
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