A properly designed SS amp running Class A, AB1, AB2, B, and C uses
about the same power and class as a tube amp may require less cooling
than the tube amp as there is no heat from a filament. Many tube amps
in the legal limit power range require fan cooling directed at the
filament pins and lower seals.
Only SS amps using exotic modes require less cooling.
To me, it makes more sense to use modern devices that can run 2400 W for
a pair of transistors per module, use a pair of modules through
combiners, design the whole works for the legal limit and you will get a
super clean amp for less than the cost of an equivalent tube amp and
without the fan noise, without the need for a lot of complicated
monitoring and protection circuitry.
Adding hardware predistortion gives an outstanding signal, while dynamic
predistortion gives an even cleaner signal.
I've used several SS, air cooled amps in the 1 to 1.2 KW range and they
did not suffer from excessive heat. In fact, they were very quiet,
unlike my tube amps.
The only legal limit amp I have that is quiet is my old HT33B, but that
legal limit was quite a bit less than today's.
73, Roger (K8RI)
On 2/21/2017 9:26 PM, Jim Thomson wrote:
Date: Tue, 21 Feb 2017 20:11:42 +0000
From: Manfred Mornhinweg <manfred@ludens.cl>
To: amps@contesting.com
Subject: Re: [Amps] SS amps watercooling - was PowerGenius XL
Hi all,
It's my humble opinion that this whole thread on how to cool high power
solid state amplifiers, using water (or evaporation, oil, freon,
whatever) is on the wrong track.
Instead of using high power amplifiers built basically like small signal
amplifiers on steroids, that is, transistors acting as RF-controlled
variable resistors that drop more or less of the supply's voltage to
produce the desired waveform, and thus incur in huge power loss that has
to be removed as heat, we should be building high efficiency amplifiers,
in which the transistors act as RF-controlled switches, so that the
power loss is tiny and can be easily handled with very modestly sized
heatsinks.
The broadcasters have been doing it for ages. It's about high time that
we "technologically advanced" hams do it too. A handful of hams are
actually doing it, but most hams still cling to antiquated and
inefficient technology, and that's really a shame.
I don't mean to blame any individual ham. For a single individual it
does take a considerable effort to think totally outside the box and
come up with a good, highly efficiency, low distortion power amplifier
that doesn't break the bank. But collectively we should be able to move
standard ham equipment technology from class AB linear amps to something
much better.
Manfred
## which broadcasters are using SSB ???
Jim VE7RF
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