The Collins ART-13 mode selector switch is voice-cw-mcw.
Perhaps Collins took it over from ham radio or vice versa?
73
Peter, DJ7WW
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of
sm0aom@telia.com
Sent: Freitag, 16. Dezember 2016 17:14
To: manfred@ludens.cl; amps@contesting.com
Subject: Re: [Amps] MOSFET amp filtering - was: auto-tune
The confusion of "Morse" and "CW" is quite typical for amateur radio, where
homemade definitions abound.
>From the beginning, "CW" was a technical feature of the transmitter to
discern it from a transmitter that generated "spark" or damped waves, which
later got the emission class "B". The only way to modulate a spark
transmitter in a meaningful way was by on-off keying using the Morse
alphabet.
When the vacuum-tube oscillator became practical, the spark transmitters
quickly faded into obscurity (except as a ship's emergency transmitter),
and the Morse code became sent by on-off keying of a CW signal. Still, the
modulation was Morse.
For some reason, the transmitter characteristic of being able to generate a
CW signal and the Morse on-off modulation came to be
used interchangeably by amateur radio in particular.
Professional radio operators and engineers have since very long referred to
Morse modulated continuous wave emissions as "A1" or just "telegraphy".
"ICW" was mentioned previously.
It was an intermediate waveform that was used in maritime radio before
receivers with beat oscillators became commonplace
which enabled them to receive unmodulated signals, and was emulating the
class B emission from a spark transmitter for interoperability reasons.
ICW had only a short period of use, primarily at shore stations whose
transmitters had been modified from spark to vacuum tube.
For the same reason, the emission prescribed on the 500 kHz maritime
distress and calling frequency up to the end of the "old system" in
February 1999 was A2A or tone modulated Morse code emissions.
73/
Karl-Arne
SM0AOM
----Ursprungligt meddelande----
Från : manfred@ludens.cl
Datum : 2016-12-16 - 13:43 (UTC)
Till : amps@contesting.com
Ämne : Re: [Amps] MOSFET amp filtering - was: auto-tune
I also shudder somewhat when I see a Morse code transmission referred to
as "continuous wave".
> That amateurs (and the entire commercial radio industry) called
> on/off keyed telegraphy "continuous wave"....
Only the radio industry does. The semiconductor industry doesn't. When
you look into the datasheet of an RF MOSFET and you see information
given for "CW" operation, they indeed usually mean a continuous wave
without any amplitude modulation, rather than an interrupted one. When
they _don't_ say CW, they mean pulsed service, usually with rather short
pulses and low duty cycles. The small print usually tells about the
pulse duration and duty cycle.
A similar confusion arises with "class AB". Hams think of class AB as
being reasonably linear, and used for almost all "linear" amplifiers.
Instead the LDMOSFET datasheets usually don't use it that way! When you
see an LDMOSFET data sheet stating an efficiency like 80% in class AB
service, they mean saturated class AB, which gives up linearity in favor
of efficiency and maximal output. After all, the only thing "class AB"
means is that the active device conducts for more than 180 but less than
360 degrees. "Class AB" doesn't tell whether or not the device is driven
into saturation. Neither does it tell how much linearizing feedback is
used, if any.
LDMOSFETS are run in class AB rather than class C, even when linearity
isn't required. The reason is that their gates can't take much negative
voltage. But for nonlinear, high efficiency amplifiers, saturated class
AB with minimal or no negative feedback is used. This is simply called
"class AB" in the datasheets, and does _not_ tell at what ratings to use
that LDMOSFET in linear service!
Life is full of pitfalls...
Manfred
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