[AMPS] RE: ALC

[measures]

>
>If it's considered useless, then why is ALC provided? 

It is a tradition.  Even though ALC makes overshoot nasties, it is 
somewhat useful if say a 200w radio were being use to drive a pair of 
572Bs.  

> And why don't
>manufacturers build their amps so that they can't be overdriven if
>ALC  can't do the job?

This is more complicated than it looks.  It depends on how many watts are 
available from the driver and how many watts the amplifier needs.  There 
is much variation.  RF-NFB resistance is one of the better solutions 
since it acts to improve amplifier linearity while making the amplifier 
harder to drive.  .  

Consider the issue of filament/heater potential adjustability.  This 
planet has line voltages that are all over the place -  so why don't 
manufacturers build their amplifiers with a simple filament/heater V 
rheostat and a jack for connecting a measuring instrument?  
During the Internet debate over "The Nearly Perfect Amplifier" (*QST*, 
1/94) , my critics argued long and hard that a rheostat simply would not 
do in filament/heater voltage control because of reliability problems.  . 
 What a load of codswallop.  
cheers.  
>
>>From: "measures" <measures@vcnet.com>
>>Date: 2/14/00  10:37:26AM
>>To: "Peter Chadwick" <Peter_Chadwick@mitel.com>,
>"'rb'"@contesting.com
>>Subject: Re: [AMPS] RE:
>>
>><rbigg@pcola.gulf.net>,
>>        "'amps'" <amps@contesting.com>
>>Mime-Version: 1.0
>>Sender: owner-amps@contesting.com 
>>Precedence: bulk
>>X-Sponsor: W4AN, KM3T, N5KO & AD1C
>>
>>
>>>
>>>Ron, K5BDJ, asks
>>>
>>>>So, is there a strong case for ALC, when the capability is there?
>>>
>>>I'll stick my neck out a bit here. ALC as it is usually
>>implemented  is a
>>>bit like shutting the stable door after the horse has bolted.
>>
>>Excellent, Peter.
....

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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