[Amps] Overdrive protection

[Carl]

OK on ancient history (-;

>From the mid 80's to current I either worked in a RF lab with access to some 
of the best test equipment or built up a suitable substitute here at home.

What I have found with SS gear that Ive tested (and that is far from all of 
them) is that there are sweet spots where the IMD is lowest and it is never 
at the advertised output. IMD will drop as the power is reduced to that 
sweet  spot and then rise again to levels that are worse than at rated 
power. I did not try any internal tweaks.

Amps that are tuned for full output and then the Load control adjusted for 
heavier loading (LESS C) until the power drops 50W or so at the 1200-1800W 
level will have the best IMD. This can be anywhere in the 2-5dB range 
depending upon the amp and tubes used.

Carl
KM1H



----- Original Message ----- 
From: "Jerry Kaidor" <jerry at tr2.com>
To: <amps at contesting.com>
Sent: Friday, July 27, 2012 12:08 PM
Subject: Re: [Amps] Overdrive protection


> Back in the late 70's I had access to some very good test equipment - I
> was working as a bench tech in an instrument shop.   I would bring in my
> ham rigs to play.  On the spectrum analyzer I would see a fundamental
> and a forest of spurii.  Turning down the drive, the fundamental would go
> down, and the spurii would generally remain the same.  Thus I came to the
> conclusion that for the best cleanliness - in terms of dB - it was best to
> run an exciter at or near its rated power.  Maybe that's changed....
>
>                        - Jerry Kaidor, KF6VB
>
>
>
>
>
>
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