I wonder why we are even discussing all this CCS versus ICAS stuff here.
We are radio amateurs, right? Not broadcasters. I fail to see what's the
sense of having a CCS amplifier for our ham use!
Let's see reality: Most hams only engage in occasional operation at less
than 50% TX time, with TX no longer than a few minutes at a time, and
mostly in reduced duty cycle modes such as SSB or telegraphy. That's
extremely light duty, and hams doing only this can get away perfectly
well with low cost amplifiers built for that sort of service.
Of course that's not good enough for every ham. So, what's really the
most demanding use hams have for their amplifiers? What comes to mind is:
- RTTY operation, at 100% duty cycle during TX, and maybe a 70/30 ratio
of TX/RX during CQ calling. That's far more severe use than SSB
chatting, but still far from CCS. And RTTY doesn't require a LINEAR
amplifier, so it would be very reasonable to switch an amplifier into
non-linear class C operation for RTTY, or at least run it in saturated
class AB (many hams do that!), to reduce loss and dissipation.
- RTTY contesting: It's the same as above, but typically over 48 hours.
It's still not CCS.
- RTTY bulletin transmission: That can be 30 minutes of full power
operation. It's still not CCS, because operation isn't 24/7, but starts
coming close, in the sense that after 30 minutes at full power an
amplifier probably has reached its thermal plateau. This kind of
operation is NOT normal ham operation, though, but is what only a very
few stations do, such as W1AW.
- The cat falling asleep on the key: That's an act of negligence, and a
ham leaving his amplifier on when walking away for a long time deserves
amplifier failure as fair punishment for creating sleeping-cat-QRM. Even
so, a good amplifier should include thermal protection, and in that case
it would shut down a while after the cat falls asleep, preventing
damage. It still doesn't need to be CCS-rated.
The only ham application that I can think of, that comes close to CCS,
is repeaters. Again not a normal ham station.
So, can anyone give a good reason why a CCS amplifier might be desirable
in a ham station, other than for bragging? As far as I can see, an ICAS
amplifier that allows enough duty cycle for the most demanding kind of
operation done at that station is a better solution than a much more
expensive, heavier, larger CCS amplifier that will never be used to its
full capability.
The anecdote of Alpha using 60 WPM dits to make people believe their
amplifier can run CCS is funny. Probably most hams visiting that booth
bought the story... Like they buy the story told by certain videos on
Youtube and manufacturer's websites demonstrating "undestructible"
LDMOSFETs while driving them at 10% duty cycle. The cheating here is in
telling people, or at least insinuating, that the actual duty cycle is
100%, when it isn't. But 60 WPM dits indeed is a reasonably good
simulation of the kind of duty cycle an amp will see in a ham station
during the most demanding types of operation, and the 10% duty cycle
pulses uses by some LDMOSFET makers is also quite representative for
many of their intended applications. So the cheating isn't in the way
the demonstration is done, but in misrepresenting what the exact
operation conditions are.
Manfred
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