[Heathkit] Suggestion for legal limit AM amp (was Heath Warrior as an AM amplifier)

[Carl]

Or 2-3 3CX800's.
If you want headroom get a 3CX3000A7 industrial amp and build what is 
needed.

Carl


----- Original Message ----- 
From: "Paul Baldock" <paul at paulbaldock.com>
To: <heathkit at mailman.qth.net>
Sent: Monday, January 16, 2012 7:31 PM
Subject: Re: [Heathkit] Suggestion for legal limit AM amp (was Heath Warrior 
as an AM amplifier)


>
> To quote W8JI http://www.w8ji.com/amplitude_modulation.htm
>
>
> In order to reproduce the input faithfully, the amplifier has to be
> loaded to handle the PEAK power. This is normally four times the
> carrier power (or more in some cases). This is because the linear has
> to be "efficiency modulated". A safe estimate is 25% carrier
> efficiency. This means your amp would be making three times the heat
> as carrier power. An SB220 can safely handle about 500 watts of
> steady dissipation (inadequate airflow to fully use the tubes) so it
> is safe at 125 watts carrier when properly tuned.
>
> Very few amplifiers can safely handle legal limit AM. Legal limit AM
> requires 375 watts of carrier power, and three times carrier power
> would be a safe power amplifier dissipation estimate for
> carrier-level heat dissipation. Typically, with a 375-watt carrier,
> over 1100 watts of heat is produced. This takes a lot of air and a
> 1200-watt or higher plate dissipation tube. An 8877 at full rated
> airflow, or a 3CX1200 series tube, would work.
>
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