Unfortunately there are very few exciters on the market that could
complement the technology Paul.
For now its still GIGO. For our junior and international readers that is
Garbage In Garbage Out, a term going back to the infancy of software
development.
Carl
KM1H
----- Original Message -----
From: "Paul Christensen" <w9ac@arrl.net>
To: <amps@contesting.com>
Sent: Tuesday, July 21, 2009 2:11 PM
Subject: Re: [Amps] Grounded Grid (Screen) 4CX250B power gain
>> "Tokyo High Power marketed a cathode driven 2 X 4X150/4CX250 amp that had
>> IMD
>> on par with grid driven.
>
> I did a "double-take" the first time I had seen one since Tokyo Hy-Power
> is
> more commonly known as a SS amp manufacturer. What's really got me
> excited
> is the use of adaptive pre-distortion in the new ADAT ADT-200A
> transceiver.
> The transceiver is now in production and has the ability to sample RF at
> the
> output of an external amp and apply complimentary non-linear distortion to
> offset inherent non-linearities in the PA chain between the rig and
> external
> amp. Adaptive predistortion is being used in the digital broadcast
> industry, although its root can probably be traced to the MIL sector.
>
> Typical 3rd-order IMD coming from the ADT-200A's 50-watt SS PA is -55dB,
> although specification is -45 dB. If the typical figure is correct,
> that's
> ~ 20 dB better than most commercial amateur SS HF amps. But the real
> power
> of that type of algorithm is its extension to any external SS PA. So, it
> would seem quite possible that one could utilize the ADT-200A, coupled
> with
> say...a Tokyo Hy-Power SS kilowatt amp and achieve IMD numbers unheard of
> with some of the best vacuum tube designs.
>
> Hopefully, one or more of the adaptive pre-distortion techniques being
> used
> are not subject to patent protection and associated licensing fees. It
> would be a great time to incorporate this technology into all new SSB
> exciters.
>
> Paul, W9AC
>
>
>
>
>
>
>
>
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