[Amps] 1 db compression point procedure ?

Carl km1h at jeremy.mv.com
Wed Jun 30 06:24:15 PDT 2010


The starting point can be wherever you want, as long as its on the linear 
slope. With a big amp its better to start close to the design load so you 
dont have to keep retuning.

Work your way up noting output vs input gain until you reach the pont of 
compression. A pulser is fine.

Carl


----- Original Message ----- 
From: "Jim Thomson" <jim.thom at telus.net>
To: <amps at contesting.com>
Sent: Wednesday, June 30, 2010 8:40 AM
Subject: [Amps] 1 db compression point procedure ?


> Ok
>
> What's the exact procedure for finding the ..'1db compression point'   on 
> a HF amp ??
>
> I have conflicting info on the procedure.   With hardly any drive, the typ 
> HF amp has a
> lot of gain.    As drive levels increase, the gain goes down.   Question 
> is.... where is the
> starting point of all this??     With 1 watt of drive... or 5w or what ? 
> It makes a big diff
> to the results.
>
> I'm assuming the amp is 1st tuned to  say normal power output... like 
> 1200-1500w out..
> IE: tune and load tweaked for max power out at normal power, then maybe 
> increase the
> loading a tiny bit  [ slightly more Un meshed].
>
> Then leave the tune and load caps alone... and reduce drive to a very 
> small amount... and   then measure
> both the drive to the amp... and also the power output of the amp  [ say 
> 1-5 w of drive.. and  20-100w out]
>  Then start increasing drive level a bit  and  measure the gain once more 
> [ it should be dropping off a bit]
>
> Does this procedure have to be done with a cxr.. or can we do it pulse 
> tuned ??    Have I even got the
> procedure any where near correct??
>
> I take it, we don't want to operate the amp beyond the point  where the 
> gain drops by 1 db ?    But
> where is the starting point ?
>
> I can also tweak the bias on the GG amp quite a bit.
>
> tnx.... Jim   VE7RF
>
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