Tom Rauch wrote:
>Some amplifiers and many radios are just barely better than class C for
>IM3 performance. It would be interesting to see where this product
>falls.
>
It also bothers me that the single-band amplifier plugins are grounded
to the case by nothing more than one banana plug (or two if you include
the +Vdd rail). This is not a good start for EMC testing.
>Jim alluded to GG amps, but in fact GG amps because of large amounts of
>negative feedback inherent in the configuration are almost always
>exceptionally clean. Tetrode amps and solid state amps are another
>story.
>
They can be clean too, but it has to be *made* to happen.
>Right now the entire bandwidth fault falls on the end user.
Unfortunately for us, it mostly falls on the people who are listening to
the end user!
>Manufacturers never have to test or comply with bandwidth regulations.
>As our hobby moves away from people skilled in the art and as it
>becomes less and less fashionable to give critical reports, a shift
>towards controls at the manufacturing end would be nice.
>
Darn right. It is a lot easier to clean up a transceiver, where the
designer can feed error signals all the way back to the SSB generator.
It's much harder to use error feedback inside a standalone amplifier.
However, if a number of different design and marketing trends converge,
we may see these compact, high-efficiency 400-500W amplifiers
incorporated into future transceivers. In the longer term, that has the
potential to bring big improvements in transmitted signal quality... but
it will take decades to retire most of the existing junk off the air.
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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