[Amps] Linear Amplifier Tuning---PROPERLY!

[Carl]

----- Original Message ----- 
From: "Eddy Swynar" <deswynar at xplornet.ca>
To: "Jim W7RY" <jimw7ry at gmail.com>
Cc: <amps at contesting.com>
Sent: Tuesday, December 20, 2011 7:47 AM
Subject: Re: [Amps] Linear Amplifier Tuning---PROPERLY!


> 
> On 2011-12-19, at 10:43 PM, Jim W7RY wrote:
> 
>> http://www.w8ji.com/loading_amplifier.htm
>> 
> 
> Hi Jim,
> 
> Here's exactly what Tom says in his website which you directed me to:
> The last few tuning steps should always be:
> 
> Load the amplifier to maximum obtainable output at full exciter drive (without exceeding amplifier short term overload ratings)
> After that, advance the loading control very slightly beyond that point (towards less capacitance). 
> 
> No mention of having to "re-tweak" the plate tuning control at all, that I can see---so does this mean "hands off" that particular knob, or that the writer is naturally assuming that one would naturally touch-up that control as a matter of course...?
> 
> ~73~ de Eddy VE3CUI - VE3XZ


What it means Eddy, as a lot of stuff from that person, is incomplete information.

Depending upon the Q the Tune cap touch may be necessary, with a fairly high bandwidth and low Q a touchup is barely if at all noticable. OTOH when the Q is high as often happens with amps trying to use a single cap 160-10M it does make a difference at 10M.

Some amps have Q's all over the place on any band so you see what your particular amp requires and do it.

This is an example of a big MAYBE where one answer is impossible but theoretically a touch up is required....sometimes (-;. 

Carl
KM1H




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