----- Original Message -----
From: "Eddy Swynar" <deswynar@xplornet.ca>
To: "Jim W7RY" <jimw7ry@gmail.com>
Cc: <amps@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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